B12-B1-Evolve-A1.txt

Graham L. Kendall
Modified 8/30/2008
Email grahamkendall74135@yahoo.com
I am found on IRC Efnet/Undernet/Dalnet as glk
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All are free to use any of this material without limit.
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===
Armored' fish study helps strengthen Darwin's natural selection theory
by PhysOrg
'Armored' fish study helps strengthen Darwin's natural selection theory
Shedding some genetically induced excess baggage may have helped a
tiny fish thrive in freshwater and outsize its marine ancestors,
according to a UBC study published today in Science Express.
Measuring three to 10 centimetres long, stickleback fish originated in
the ocean but began populating freshwater lakes and streams following
the last ice age. Over the past 20,000 years - a relatively short time
span in evolutionary terms - freshwater sticklebacks have lost their
bony lateral plates, or "armour," in these new environments.
"Scientists have identified a mutant form of a gene, or allele, that
prohibits the growth of armour," says UBC Zoology PhD candidate Rowan
Barrett. Found in fewer than one per cent of marine sticklebacks, this
allele is very common in freshwater populations.
Barrett and co-authors UBC post-doctoral fellow Sean Rogers and Prof.
Dolph Schluter set out to investigate whether the armour gene may have
helped sticklebacks "invade" freshwater environments. They relocated
200 marine sticklebacks with the rare armour reduction allele to
freshwater experimental ponds.
"By documenting the physical traits and genetic makeup of the
offspring produced by these marine sticklebacks in freshwater, we were
able to track how natural selection operates on this gene," says Rogers.
"We found a significant increase in the frequency of this allele in
their offspring, evidence that natural selection favours reduced
armour in freshwater," says Barrett.
Barrett and Rogers also found that offspring carrying the allele are
significantly larger in size. "It leads us to believe that the genetic
expression is also tied to increased growth rate," says Barrett.
"If the fish aren't expending resources growing bones - which may be
significantly more difficult in freshwater due to its lack of ions -
they can devote more energy to increasing biomass," says Barrett.
"This in turn allows them to breed earlier and improves over-winter
survival rate."
Celebrating its 150th anniversary this week, Darwin's first
publication of his natural selection theory proposed that challenging
environments would lead
to a struggle for existence, or "survival of the fittest." Since then,
scientists have advanced the theory by contributing an understanding
of how genes affect evolution.
"This study provides further evidence for Darwin's theory of natural
selection by showing that environmental conditions can directly impact
genes controlling physical traits that affect the survival of
species," says Barrett.

==
Within the Order Cetecea, whales are divided into two sub-orders: the
Odonteceti (toothed whales), which includes sperm whales, killer whales and
dolphins, all of which eat fish and flesh; and the Mysticeti (baleen whales),
which live by filtering plankton through a hairy sieve-like substance called
baleen, these include blue whales, humpback whales and right whales. The
difference in feeding habits might lead one to theorise an entirely separate
ancestry for the two groups, but in fact studies have shown that all whales
are descended from a common ancestor. The nature of this ancestor has been the
subject of great debate and speculation, because of the amazing adaptations of
these mammals to life in the water.
Introduction: Modern Whales
Before we begin, we should look briefly at the nature of modern whales. As
stated, whales are mammals, a fact betrayed by their warm-blooded circulatory
system, by the small hairs that can be found on their bodies, by the fact that
they give birth to live young, not to eggs, and by the fact that they inhale
air into their lungs rather than filter oxygen through gills. Collectively,
all whales and dolphins are known as the order Cetecea.
Modern whales are splendidly adapted to a permanent life in the sea.
Their unique ears enable them to hear perfectly underwater.
They have no legs, moving instead with flippers and the flukes of their huge
tails.
They do not have nostrils, having instead a single blowhole on top of their
heads, which allows them to breathe while mostly submerged.
They are able to give birth underwater, instead of coming onto the land like
seals.
The Odonteceti can use ultrasound to hunt, while all whales communicate with a
complex language of 'songs' that carry for miles underwater.
Within the Order Cetecea, whales are divided into two sub-orders: the
Odonteceti (toothed whales), which includes sperm whales, killer whales and
dolphins, all of which eat fish and flesh; and the Mysticeti (baleen whales),
which live by filtering plankton through a hairy sieve-like substance called
baleen, these include blue whales, humpback whales and right whales. The
difference in feeding habits might lead one to theorise an entirely separate
ancestry for the two groups, but in fact studies have shown that all whales
are descended from a common ancestor. The nature of this ancestor has been the
subject of great debate and speculation, because of the amazing adaptations of
these mammals to life in the water.

Why Leave the Land?

Although the transformation from land animal to sea creature may seem
extraordinary, the origins of such an occurrence may be observed among some
communities of sheep that live on the coast of Scotland. These wild, goat-like
sheep have lived on the coast for hundreds of years, and like to eat seaweed
and kelp. They like seaweed so much that they are often observed swimming out
into shallow waters to find it. Perhaps if we returned in ten million years,
the descendants of these sheep would be seal-like or even whale-like
creatures. And if herbivorous creatures are prepared to brave the seas for
food, it would be even more attractive for those that were able to eat fish.

However, while such theories are easy to hypothesise, proof has been lacking,
and for a long time the fossil evidence for early whales was virtually
non-existent.

The First Finds

The first fossil evidence for early whales arrived with the 1840 discovery in
Egypt of Basilosaurus, an enormous, 40-million-year-old creature with a long,
serpentine body, which was very whale-like in appearance, but also had tiny,
useless hind legs indicative of a land-based origin. However, the discovery of
Basilosaurus did not help greatly with the major questions of whale ancestry,
since the creatures were so similar to modern whales that it remained
difficult to imagine what their land-based ancestors were like.

More intriguing evidence for the land-based ancestors of whales arrived with
the discovery of the Mesonychids, an extinct type of mammal that flourished
between 60 and 30 million years ago. Mesonychids were ungulates (hoofed
animals), but unlike all other known ungulates they were meat-eaters. Many of
them, including the terrifying Andrewsarchus, looked like wolves with hooves.
Their most important feature, for our purposes, was their unusual, triangular
teeth. The only other animals that have teeth similar to these are whales. For
this reason, scientists long believed that whales must have evolved from a form
of Mesonychid. Better evidence, however, remained elusive, and it was still
difficult to imagine a transitional form between a Mesonychid and the
whale-like Basilosaurus.

A further suggestion was made by scientists studying DNA rather than fossils.
They found that whale DNA was more similar to that of the Hippopotamids than
any other living animal, and some subtle physical similarities between whales
and hippos have also been noted. Could the origins of whales and hippos be
linked?

All of these suggestions have been clarified, and considerably altered, by a
number of recent discoveries in Pakistan and India, which not only tell us
more about the earliest whales, but also question the Mesonychid theory. Let
us now look at the 'proto-whales' in chronological order.

Pakicetids

The earliest proto-whale that has been discovered is now Pakicetus, one of a
group of creatures labelled the Pakicetids which lived around 52 million years
ago. Pakicetus was about the size of a wolf. It looked nothing like a whale,
and more like a cross between a large dog and a rat, having a long, thick
tail. Despite this, many features of its skeleton link Pakicetus more closely
to whales than to any other family. In particular, its ears, though not as
sophisticated as those of modern whales, show the beginnings of this
adaptation to underwater hearing. It is not known exactly how the Pakicetids
lived, but they may have roamed the seashore, or hunted in rivers.

The discovery of Pakicetus demonstrated the falsity of the Mesonychid theory;
although the teeth indicate a shared ancestry, the skeletons of Pakicetus
demonstrate that whales did not derive directly from Mesonychids. Instead,
they are a form of Artiodactyl (another type of ungulate) which began to take
to the water after the Artiodactyl family split from the Mesonychids. Thus,
Pakicetids are early Artiodactyls that retain aspects of their Mesonychid
ancestry which modern Artiodactyls have since lost.

The Pakicetid fossils also helped to clarify the relationship of whales and
hippos. It now seems that they are not very close relatives, except in that
both are Artiodactyls. The likeliest explanation for the physical and genetic
similarities is that hippos split off from the main Artiodactyl branch shortly
after the whales did, and thus, like whales, retain some characteristics of
early Artiodactyls. Both hippos and whales are Artiodactyls that became
adapted to life in the water, but they did so separately and evolved in quite
different directions.

Ambulocetids

While Pakicetus was clearly a land animal with minor adaptations to life in
the water, this is less true of the recently discovered Ambulocetus, a 50
million-year-old skeleton of which was recently unearthed in Pakistan. The
three-metre long Ambulocetus was an alarming animal that looked like a
mammalian crocodile, having a long snout filled with teeth. It was amphibious
- its back legs are better adapted for swimming than walking on land - and it
probably swam by undulating its back vertically, as otters, seals and whales
do. Like Pakicetus, Ambulocetus had developed an early form of the specialised
ears possessed by modern whales, but there was still no blowhole. It is not
certain whether these animals lived in rivers, the sea, or both. It has been
suggested that Ambulocetids hunted like crocodiles, lurking in the shallows to
snatch unsuspecting prey.

Remingtonocetids

The Remingtonocetid family were smaller cousins of the Ambulocetids, and lived
at a similar time. They had longer snouts than those of Ambulocetus, and were
slightly better adapted for underwater life. They probably lived similarly to
modern sea otters, hunting for fish in the shallows.

Protocetids

The Protocetids were better-adapted for the water and lived around 45 million
years ago. The best-known is Rhodocetus. The major Protocetid adaptation was
the appearance of flukes (horizontal bars) on their tails, which enabled
faster swimming. However, the skeletons of Rhodocetus indicate that they
retained substantial hind legs. They lived in shallow seas, and may have had a
similar lifestyle to seals, or even dolphins; it is not clear whether they ever
came onto the land.

Basilosaurus and Dorudon

These new discoveries make it possible to understand how the descendants of
creatures like these could look like Basilosaurus1. Basilosaurids lived around
38 million years ago and retained tiny, useless back legs. They were monsters,
up to 18m long. Meanwhile, Dorudontids, which lived at the same time, were
dolphin-sized, about 5m long. Although they look very much like modern whales,
Basilosaurids and Dorudontids lacked the 'melon organ' that allows their
descendants to sing and use ultrasound. They also had small brains, which
suggests that they were solitary and didn't have the complex social structure
of modern whales.

Summary

The transition from hoofed carnivore to sea leviathan is now understood in
more detail than was possible even ten years ago. Pakicetids evolved into
whales in a remarkably short time - about eight million years. However, these
amazing transformations can now be observed in the fossil evidence of
creatures that represent intermediate stages in the process. Gaps in our
knowledge still remain - in particular the evolution of the blowhole remains
mysterious - but hopefully further discoveries will provide answers to these
questions.
==
The Antiquity of Man
Similarities between apes and humans, and the implications for human evolution
by Mikey Brass
The anatomical evidence - both fossil and contemporary - demonstrates that
australopithecines and chimpanzees share a geologically recent common ancestor
and that Homo sapiens are descendants of the evolutionary branch that began
with the divergence of the australopiths.
The anatomical characteristics that link the australopiths to Homo, and show
their intermediate form between modern humans and the last common ancestor
between humans and chimpanzees, include:
* The canines of the australopiths do not project much further forward in
relation to the other teeth than they do in Homo;
* Australopith canines also show a decrease in sexual size differences over
time - the more recent forms are more like the condition of modern humans;
* Tooth enamel progresses to a more Homo-like thickness over time;
* Wear patterns on australopith teeth suggest a "crushing" action, similar to
that of Homo;
* The cranial capacity of the australopiths increases to a capacity range
approaching that of early Homo;
* The australopith foramen magnum, which allows the spinal cord to connect
with the base of the brain, is located more toward the base of the skull than
in apes, yet not completely under the skull, as in Homo but excluding the
robust australopiths (also known as Paranthropus) where it was just as in
Homo; and
* The features of the tibiae (orientation angle, thickness and internal
structure) shared by australopiths and Homo reflect the demands placed on
their bodies by bipedalism.
The anatomical similarities between chimpanzees and anatomically modern humans
(Homo sapiens) can be summarized as follows:
* In both species, the rib cage is broad from side to side and shallow from
front to back; the rib cage extends back beyond the vertebral column
* Both have a dorsally-placed scapula and shoulder joints facing outward to
the side, giving humans a mobile shoulder joint; a hangover from our arboreal
ancestry; and
* The positioning and angle of the humeral shaft and humeral head and other
joints in the forelimb are the same in both species.
Table 1 below summaries the similarities and differences between chimpanzees,
australopiths and modern humans as a result of millions of years of evolution.
Modern chimpanzees     Australopiths     Modern humans
Canines larger and project out from tooth row     Canines slightly larger, but
non-projecting     Canines of similar size to other teeth and non-projecting
Extended canine size determined by sexual dimorphism     Moderate canine size
determined by sexual dimorphism     Minimal canine size determined by sexual
dimorphism
Thin tooth enamel     Moderate tooth enamel     Thick tooth enamel
Dental wear pattern shows grinding action     Dental wear pattern shows
crushing action     Dental wear pattern shows crushing action
Cranial capacity average 400 cc     Cranial capacity 350 - 540 cc     Cranial
Capacity > 1000 cc
Foramen magnum opens toward rear of skull     Foramen magnum opens between
rear and base of skull     Foramen magnum opens at base of skull
Tibiae thin and angled      Tibiae thicker and straighter     Tibiae thick and
straight
Rib cage broad and extends past vertebral column     Rib cage broad and
extends past vertebral column     Rib cage broad and extends past vertebral
column
Scapulae on the back, shoulder joints oriented to the sides     Scapulae on
the back, shoulder joints oriented to the sides     Scapulae on the back,
shoulder joints oriented to the sides
It is also worthwhile noting Bernard Wood and Brian Richmond's (2000) summary
of comparative limb morphology: "The substantial differences between the lower
limbs of modern humans and apes are largely attributable to the bipedal
locomotion of the former. The most striking difference is the great absolute
and relative length of modern human lower limbs that increases stride length
and thus the speed of bipedal walking. Because the lower limbs support the
body during bipedal gait, the acetabulum, femoral head and other lower limb
joints are relatively larger in humans. Modern human femora are distinctive in
that they show the valgus condition (i.e. they converge towards the knees),
thus helping to position the feet closer to the midline."
In addition, recent reviews of the available anatomical (Shoshani et al. 1996)
and genetic evidence (Ruvolo 1995, 1997; Wise et al. 1997) have convincingly
re-affirmed yet again the theory that apes and anatomically modern humans
share a common ancestry. The DNA sequences of human chromosomes 2 and 4 have
been completely analysed and were published in the April 7 (2005) issue of
Nature, reinforcing the conclusions reached by previous studies. In essence,
the chimp chromosomes 2a and 2b fused to form the human chromosome 2. Previous
comparisons between the chimpanzee and human genomes and other known genomes
have yielded a gene which appears to be functional only in chimpanzees and
humans. This gene is suggested to make a protein in the brain and testicals.
Furthermore, , geneticists have analysed the differences in the amino acid
sequences of protein and in the base sequences of DNA from apes and humans;
the results have yielded a divergence time-frame of 5-8 million years ago.
A good case study is that of the Dikika child, first published in 2006 and
found by the Dikika Research Project members in Ethiopia. The sandstone
sediment in which the child was found was deposited on a subaerial delta
plain; the age of the Sidi Hakoma Member ranges from 3.31 - 3.35 million
years. When combined with the lack of pre-weathering of the anatomical
remains, these factors indicate that the child was buried in a flood.
The initial anatomical report (Alemseged et al. 2006) is the accumulation of
five years of painstaking cleaning and examination. Most of the postcranial
remains were covered by sandstone matrix, together with the cranium's midface,
left temporal bone and the cranial base.
Analysis of the skeletal elements places the child firmly within the known
range for Australopithecus afarensis and distinguish them from modern gorillas
and chimpanzees. CT-scans were used to model the age using an African ape
model. The resulting 3 years of age would not differ by more than a year and a
half if a modern human model had been used instead. Given that A. afarensis is
a hominin, the utilisation of an African ape model is a prudent measure for a
minimum age.
The tibiae has a sharper anterior border and its muscle attachment
orientations resemble that of modern humans'. In addition, also like modern
humans, the side of the upper part of the shaft is a little concave, becoming
convex towards the back. The ape-like scapula, the longer phalanges and the
reconstructed environmental settings (woodland with a nearby plain) all
combine to reinvigorate investigations into the mobility patterns of A.
afarensis. The basis of these investigations will likely be that A. afarensis
combined a form of arboreal behaviour with habitual bipedalism, as reflected
by the more derived lower body which would have been under heavy selection
pressures.
As more of the sandstone matrix is removed from the skeletal remains and
further analysis is made possible (hopefully including isotope analysis),
expect to see the new models of hominin growth, dietary and evolutionary
patterns emerging over the coming years. These will yield valuable insights
which can then be tested against the known and future anatomical remains of
both A. afarensis and other hominin species.
These models and predictions are based upon detailed anatomical evidence and
do not use any particular religious text either as the starting point or as
the given conclusion. Those who back such fundamentalist works display a
profound ignorance of basic 1st year scientific methods, which places a huge
question mark over the reliability of their own published and presented works.
Creationist works, and those who support such efforts, have no basis whatsoever
in any scientific procedure and basic plain scientific reality.

References

Alemseged, Z., Spoor, F. Kimbel, W., Bobe, R., Geraads, D., Reed, D. & Wynn,
J. 2006. A juvenile early hominin skeleton from Dikika, Ethiopia. Nature
443(21): 296-301

Jungers, W.L. 1988. Relative joint size and hominoid locomotor adaptations
with implications for the evolution of hominid bipedalism. In, Strasser, E. &
Dagosto, M. (eds.) The Primate Postcranial skeleton: Studies in Adaptation and
Evolution, pp. 247-265. London: Academic Press

Pilbeam, D. 1996. Genetic and morphological records of the Hominoidea and
hominid origins: a synthesis. Molecular Phylogenetics and Evolution 5: 155-168

Richmond, B. & Strait, D. 1999. Knuckle-walking traits retained in the wrists
of early hominids. American Journal of Physical Anthropology, Suppl. 28: 232

Shoshani, J. et al. 1996. Primate phylogeny: morphological vs molecular
results. Molecular Phylogenetic Evolution 5: 101-153

Tardieu, C. & Trinkaus, E. 1994. Early ontogeny of the human femoral
bicondylar angle. American Journal of Physical Anthropology 95: 183-195

Walmsley, T. 1933. The vertical axes of the femur and their relations. A
contribution to the study of erect posture. Journal of Anatomy 67: 284-300

Washburn, S.L. 1967. Behaviour and the origin of Man. Proceedings of the Royal
Anthropological Institute 3: 21-27

Wise, C. et al. 1997. Comparative Nuclear and Mitochrondrial Genome Diversity
in Humans and Chimpanzees. Molecular Biology Evolution 14(7): 707-716

Wood, B. & Richmond, B. 2000. Human evolution: taxonomy and paleobiology.
Journal of Anatomy 196: 19-60

Wynn, J. Alemseged, Z., Bobe, R., Geraads, D., Reed, D. & Roman, D. 2006.
Geological and palaeontological context of a Pliocene juvenile hominin at
Dikika, Ethiopia. Nature 443(21): 332-336
==
Perhaps the first and certainly the greatest example of an in-betweenie was
Russian-born biologist Theodosius Dobzhansky. He showed what could be achieved
when white coats were combined with wellingtons. Back in the 1930s, he began
dusting down Darwinian evolution to leave it looking modern, shiny and new.

In the early decades of the 20th century, with Darwin dead and Mendel on their
minds, scientists were creating an entirely new way of looking at evolution.
Instead of thinking about populations of plants and animals as collections of
individuals, biologists like Dobzhansky began thinking exclusively in terms of
genes and gene pools. As good as Darwin's evolutionary argument was, it had
always lacked direct experimental evidence. By combining the fledgling science
of genetics with Darwinian evolution, Dobzhansky gave Darwin's ideas the
empirical kick up the backside they had been crying out for.

But Dobzhansky's success was no solo affair. He would have got nowhere without
his insect comrade, the fruit fly, Drosophila pseudoobscura. His choice of
experimental organism may have seemed unusual. After all, Dobzhansky's tiny
fruit flies were hardly a match for Darwin's finches, or so it seemed. But
Dobzhansky chose wisely. By the 1930s, fruit flies had already proved
themselves as pioneers in genetics research. They were cheap, prolific and
easy to breed. They also had the biggest chromosomes that anyone had ever seen.

Fruit flies, like footballers, produce immense quantities of saliva. The
chromosomes inside the fruit fly's salivary glands are huge - a thousand times
thicker than normal. Each chromosome is like a packet of spaghetti, made up of
many parallel strands of DNA that have failed to separate. Chemical staining
of these super-sized chromosomes reveals dark horizontal bands along their
length, distinct landmarks corresponding to the positions of specific genes.
When these chromosomes were first discovered in the 1930s, it was as
revolutionary as the discovery of genetic fingerprints fifty years later.
These super-sized chromosomes were like biological barcodes that gave
biologists the first direct glimpse of genetic differences between individuals
and populations.

To Dobzhansky, the fruit fly chromosomes were a godsend and he spent years in
the Californian wilderness collecting flies for analysis in the laboratory.
His first discovery was that populations of flies living in different areas
could be distinguished by the banding patterns of their chromosomes. In other
words, populations were not genetically uniform, but differed from place to
place. This may sound like common sense today and, even back then, it was what
many biologists had suspected but it was the first time that anyone had
provided the experimental proof. Yet more amazing was the discovery that these
genetic differences were not static, but could change over remarkably short
time scales. In the struggle for existence, natural selection favoured
different chromosome types at different times of the year. These results were
epoch-making for evolutionary biology. Because Darwinian natural selection had
traditionally been considered a slow paced affair that was difficult - if not
impossible - to test experimentally, critics had often dismissed the subject
as unscientific. But here was a perfect demonstration of evolution in action.
This was no million-year wait for a two millimetre increase in the length of a
leg bone. This was evolutionary change in front of your very eyes.

In accumulating genetic differences, Dobzhansky saw how two populations might
also accumulate differences in body size, colour, genital architecture,
behavioural idiosyncrasies, and a thousand other characteristics that could
eventually make them reluctant or unable to mate with one another. In these
distinct genetic profiles, Dobzhansky believed he was seeing the origin of
species in its infancy.

Dobzhansky had shown what was possible when scientists were willing to abandon
their prejudices and break with tradition. His experiments with the fly brought
about a sea change in evolutionary attitudes. Fruit fly genetics made evolution
and the origin of species more credible to a once sceptical scientific
community. Genetics not only tightened up Darwin's theory, it also turned
evolutionary biology into a rigorous experimental science. Darwin would have
given anything for a share of Dobzhansky's experimental spoils. Serves him
right for looking at finches rather than flies.

Fly: An Experimental Life, by Martin Brookes, is published by Weidenfeld &
Nicholson, 16.99.
==
Whale barnacles are in the Coronulidae, which are highly specialized for life
on living marine organisms.  Coronula is found at Calvert, but is a very low
conic species, with 'hooks' on the base of the shell plates which embed the
shell into the skin of the whale.  It is impossible to remove the barnacle
from a living whale without cutting out a patch of skin.  More specialized 
Coronulidae embed completely into the skin, with only the aperture on the
surface.  These species have no or very reduced shell plates, and would be
difficult to recognize as fossils.
==
Miller, Stanley L., 
1953 łA Production of Amino Acids Under Possible Primitive Earth 
Conditions˛ Science vol. 117:528-529 

With a bit more information included in: 

Miller, Stanley, Harold C. Urey 
1959 łOrganic Compound Synthesis on the Primitive Earth˛ Science vol 
139 Num 3370: 254-251 
==
Acanthostega, had both lungs and gills. 
http://www.devoniantimes.org/ has transitionals
==
http://evolution.berkeley.edu/
http://www.natcenscied.org/article.asp
http://www.ncseweb.org/resources/articles/7719_responses_to_jonathan_wells3_11_28_2001.asp
==
Birds release the fluke's eggs in their droppings, which are eaten by horn
snails. The eggs hatch, and the resulting flukes castrate the snail and
produce offspring, which come swimming out of their host and begin exploring
the marsh for their next host, the California killifish. Latching onto the
fish's gills, the flukes work their way through fine blood vessels to a nerve,
which they crawl along to the brain
They don't actually penetrate the killifish's brain but form a thin
carpet on top of it, looking like a layer of caviar. There the parasites wait
for the fish to be eaten by a shorebird. When the fish reaches the bird's
stomach, the flukes break out of the fish's head and move into the bird's gut,
stealing its food from within and sowing eggs in its droppings to be spread
into marshes and ponds.
==
The name "colobus" is derived from the Greek word meaning
"docked" or "mutilated." Colobus monkeys once were thought
to be abnormal because they have no thumb, or only a small
stub where the thumb would usually be. This is actually an
adaptation rather than a mutilation which allows colobus monkeys
to easily travel along the tops of branches quadripedally.
==
Researchers See History of Life in the Structure of Transfer RNA

Transfer RNA is an ancient molecule, central to every task a cell
performs and thus essential to all life. A new study from the
University of Illinois indicates that it is also a great historian,
preserving some of the earliest and most profound events of the
evolutionary past in its structure.
The study, co-written by Gustavo Caetano-Anolle s, a professor of crop
sciences, and postdoctoral researcher Feng-Jie Sun, appears March 7
in PLoS Computational Biology. Caetano-Anolle s is an affiliate of the
U. of I. Institute for Genomic Biology.
Of the thousands of RNAs so far identified, transfer RNA (tRNA) is
the most direct intermediary between genes and proteins. Like many
other RNAs (ribonucleic acids), tRNA aids in translating genes into
the chains of amino acids that make up proteins. With the help of a
highly targeted enzyme, each tRNA molecule recognizes and latches
onto a specific amino acid, which it carries into the protein-
building machinery. In order to successfully add its amino acid to
the end of a growing protein, tRNA must also accurately read a coded
segment of messenger RNA, which gives instructions for the exact
sequence of amino acids in the protein.
The fact that tRNA is so central to the task of building proteins
probably means that it has been around for a long time, Caetano-
Anolles said. His inquiry began with a hunch that understanding the
structural properties of tRNA would shed light on how organisms and
viruses evolved.
"Perhaps in evolution there are things that are so fundamental that
they are kept, held onto, for millions or even billions of years,"
Caetano-Anolle s said. "Those are the fossils, the molecular fossils,
that tell us about the past. Therefore, studying these molecules can
address fundamental questions in biology and evolution."
All tRNAs assemble themselves into a shape that, if flattened,
resembles a cloverleaf. The team began by looking for patterns in
this cloverleaf structure, using detailed data from hundreds of
molecules representing viruses and each of the three superkingdoms of
life: archaea, bacteria and eukarya.
The researchers converted all distinguishing features of the
individual tRNA cloverleaf structures into coded characters, a
process that allowed a computerized search for the
most "parsimonious" (that is, the simplest, most probable) tRNA
family tree. They conducted the same analysis on the tRNAs of each of
the superkingdoms, to see how far these groupings diverged from the
overall tree. This comparison allowed them to determine the order in
which viruses and each of the superkingdoms diverged.
The new analysis supports an earlier study that suggested that the
archaea were the first to arise as an evolutionarily distinguishable
group. Archaea are microbes that can survive in boiling acid, near
sulfurous ocean vents or in other extreme environments. The earlier
study, also led by Caetano-Anolle s, analyzed the vast catalog of
protein folds  those precisely configured regions in proteins that
give them their functionality  as a guidebook to evolutionary
history.
"The transfer RNA data matches our earlier data," Caetano-Anolle s
said. "This is important because two lines of independent evidence
are supporting each other."
The new analysis also indicates that viruses emerged not long after
the archaea, with the superkingdoms eukarya and bacteria following
much later  and in that order. This finding may influence the
ongoing debate over whether viruses existed prior to, or after, the
emergence of living cells, Caetano-Anolle s said.
"This supports the idea that viruses arose from the cellular domain,"
he said.
==
Examples of transitions in the fossil record In the '70s, creationist
polemicist Gish predicted that proto-mammals with two jaw joints would never
be found. Promptly thereafter, lots of them were from all around the world,
despite the far from ideal conditions of their environments & small size for
fossilization. (The older jaw joint became the mammalian inner ear bones,
while the newer jaw joint is the one that creationists share with asses.)
More recently, ID advocate Behe predicted that walking whales would never be
found, but was just as promptly shown wrong. Evolution predicts transitional
fossils, & they're found, while creationists' predictions are
always shown false.
==
Inactivation of the EGF-TM7 receptor EMR4 after the Pan-Homo divergence
We here report on the identification of a novel human EGF-TM7 receptor,
designated EMR4. Like most EGF-TM7 receptor genes, EMR4 is localized on the
short arm of chromosome19, in close proximity to EMR1. Remarkably, due to a
one-nucleotide deletion in exon8, translation of human EMR4 would result in a
truncated 232-amino acid protein lacking the entire seven-span transmembrane
region. This deletion is not present in nonhuman primates, including
chimpanzees, suggesting that EMR4 became nonfunctional only after human
speciation, about five million years ago. Thus, EMR4 surprisingly accounts for
a genetic difference between humans and primates related to immunity.
==
The centromere (middle connection) of human chromosome #2 is composed of the
telomeres (end caps) of two smaller standard ape chromosomes, demonstrating an
important genetic event in human evolution.
Chromosome centromeres are also useful in tracing the
surprisingly recent evolution of some species of genus
Equus, ie horses, donkeys & zebras:
http://www.ncbi. nlm.nih.gov/ pubmed/16413164
Single genus Equus shows about the same genetic
distance among its species as do humans with our
closest relatives, the great apes, despite humans,
chimps (with bonobos), gorillas & orangs all having
been awarded our own genera, Homo, Pan, Gorilla & Pongo.
==
Monkey DNA Points to Common Human Ancestor
A rhesus macaque pictured at the Southwest National Primate Research Center. A
female from the center provided the DNA sample used in the genome sequencing.
Credit: Southwest National Primate Research Center at Southwest Foundation for
Biomedical Research in San Antonio
A rhesus macaque pictured at the NIH Animal Center in Poolesville, MD. Credit:
Science/Joshua Moglia
The first primate to get rocketed into space and to be cloned, the rhesus
monkey, has now had its genome sequenced, promising to improve research into
health and yield insights into human evolution.
Analysis of the monkey's DNA sequence has also deepened a few mysteries in our
understanding of the biology of primates when it comes to vital parts of our
biology, such as the X chromosome.
Rhesus macaques (Macaca mulatta) are sandy-furred, pink-faced monkeys that
live in the region ranging from Afghanistan to northern India, as well as
southern China, and are traditionally held as sacred in Hinduism.
They have a long history as lab monkeys. For instance, the Rh factor in blood
discovered in 1937, the presence or absence of which dubs a person's blood
type either 'positive' or 'negative,' derives its name from rhesus monkeys.
Even now, they are the animals of choice for research into drug addiction and
HIV, and roughly two-thirds of all National Institutes of Health-funded
primate-related studies use the monkeys. For example, the rhesus monkey Tetra,
born in 2000, was the first cloned primate.
93 percent common DNA
The sequence of the rhesus macaque's genome will be a powerful tool for
research with the monkeys aimed at understanding human biology, said
consortium leader Richard Gibbs, director of the Baylor College of Medicine's
Human Genome Sequencing Center in Houston.
"Right now if you perform an experiment on a person, there's no way that you
would think that all people are the same, when it comes to a response to a
drug or behavior or anything," Gibbs told LiveScience. Macaques have about the
range of diversity when it comes to their genetics, "so being able to
understand them on a genetic level will help explain variation in their
responses and will allow for smarter experiments that make us more clever at
deciphering results."
The new analysis of the rhesus monkey genome, conducted by an international
consortium of more than 170 scientists, also reveals that humans and the
macaques share about 93 percent of their DNA. By comparison, humans and
chimpanzees share about 98 to 99 percent of their DNA.
The fact that rhesus monkeys are further away from humans in evolution will
help illuminate what makes humans different from other apes in ways that
chimps, which are so closely related to us, could not, Gibbs said. (Rhesus
monkey ancestors diverged from those of humans roughly 25 million years ago,
while chimpanzees diverged from our lineage 6 million years ago.)
In addition, the researchers identified roughly 200 genes that appear to be
key players "in defining the shapes of species, in what makes the primates
different from us and each other," Gibbs said. These include genes involved in
hair formation, sperm-egg fusion, immune response and cell membrane proteins,
findings detailed in the April 13 issue of the journal Science.
Unusual role of X chromosome
The research also raised a few surprises. For instance, the monkey's X
chromosome showed an unexpectedly large number of times in which its parts got
shuffled around. This is consistent with the same mysterious rearrangements
seen in the human lineage's X chromosome following the branching off of the
chimpanzee, and gives "us new evidence of the unusual role of this sex
chromosome in primate evolution," said researcher Aleks Milosavljevic at the
Baylor College of Medicine.
Another as yet unexplained phenomenon the sequencing revealed has to do with
lumps of DNA known as centromeres, which hold together the two separate
strands of DNA that make up a chromosome, acting somewhat like the center of
an X. Strangely, nine of the 22 centromeres the monkeys have repositioned
themselves on their chromosomes in the last 25 million years. As to why this
happened, "no one knows," said researcher Mariano Rocchi at the University of
Bari in Italy.
The rhesus monkey genome sequence should prove invaluable to biomedical
research, said physician scientist Ajit Varki at the University of California
at San Diego, who participated in the chimpanzee genome sequencing project.
"And if we can get the genome sequences of one representative from each
primate lineage, we could reconstitute the ancestral primate genome--what the
genome of our common ancestor some 40 to 50 million years ago looked like," he
told LiveScience. "That would be an amazing feat."
==
Scientists  found life in a 2-mile-deep mine in South Africa, that's the first
case of discovering life that is completely independent of what happens on the
surface. The microbes live off of gases from radioactive activity produced in
the rock.
==
Native to Arizona, these whip tail lizards somehow managed to entirely
eliminate the male of the species.
As a result, the lizards are what scientists call "parthenogenetic unisexual
pseudocopulators." Since there are no males, the females reproduce on their
own, making exact copies of themselves.
However, the lizards still need another woman to get the job done. A female,
noted by her small undeveloped eggs, will hop on another female who has rich,
robust, ready-to-be-fertilized eggs, and mock humps her.
==
Hormone governs caterpillar's bird dropping disguise
A hormone is the secret behind the unusual ability of
young swallowtail caterpillars to disguise themselves as bird droppings and
then copies of the leaves they live on before becoming butterflies, Japanese
researchers found.
Writing on Thursday in the journal Science, the researchers said a special
hormone -- juvenile hormone -- keeps larvae of the butterfly Papilio xuthus,
which is commonly found in Japan, in their black and white bird-excrement
camouflage.
As they reach the last stage of caterpillar development, levels of this
hormone drop, triggering a transformation into the green leaf phase.SEMEN
"We found that juvenile hormone works as a switch for the camouflage pattern.
That is a novel aspect of this hormone," Haruhiko Fujiwara of the National
Institute of Agrobiological Sciences in Japan, who worked on the study, said
in an e-mail.
Juvenile hormones are known to regulate many aspects of insect development
including molt -- when an insect sheds its outer shell -- and metamorphosis --
as when a caterpillar becomes a butterfly, he said.
What Fujiwara and colleagues discovered, however, was that juvenile hormone
also appears to govern this camouflage process. He said the hormone may
regulate genes involved in color, pattern and surface formation.
As for the bird-poop disguise, Fujiwara said it likely keeps the larvae safe
from hungry birds until they are more mobile, but they did not study this.
==
What did the immediate ancestor of chimps and humans look like?

Comparing living chimpanzees to living humans, in reference to the species
that gave rise to these two closely related species, is one way to frame
questions about the evolution of each species.

Generally, it is useful to address evolutionary questions by comparing two
living species with the reconstructed "last common ancestor" (LCA) of those
species. All of the similarities and differences between the LCA and the
living form, in each lineage, represent evolutionary "stories" (that could
even be worked out as hypotheses). Similarities indicate important,
long-maintained adaptations, and differences indicate evolutionary changes
that are ripe for exploration. The different stories that go with each lineage
may reflect historically important events, such as the effects of biogeography,
climate change, or other changes in the ecology or behavior of the organisms.

One argument that has emerged over the last several years, championed by David
Pilbeam and Richard Wrangham, and used by Wrangham and me is our paper on Roots
and the evolution of Australopithecus (and related species), is that the
chimp-human LCS can be modeled as a chimp-like organism. This argument implies
that chimps have not changed much since the chimp-human split, while most of
the changes have been along the human lineage. One might think that this is a
human-centric approach, but it is not. It is simply taking the available
evidence for what it means and going with it.

This argument is based on triangulation. Imagine a phylogeny (family tree)
showing gorillas, chimps, bonobos, and humans. Based on the genetic evidence,
it would look something like this:

Using apes in general as a reference point, the gorilla-chimp ancestor is
likely to have been a chimp-like form. Gorillas seem to have evolved from a
chimp like ancestor, with a change in growth pattern to make gorillas both
larger and more sexually dimorphic (dimorphic = "different shape") in body
size, and to have derived features of their teeth.

Again, using apes in general as a reference point, everything that seems to be
different between bonobos and chimps seems most likely to be a derived feature
added to bonobos. This suggests that the LCA of chimps and bonobos is more
like a chimp than a bonobo.

When we look at fossils of early human ancestors, from back near to the
chimp-human split, we see mostly chimp-like features with a mix of derived
(added on) features depending on which early hominid species we look at. Most
of the differences in postcrania are minor (even given bipedalism) and most of
the differences in the skull have to do with a single set of related changes in
dentition that relate to a dietary shift. Again, we see chimp-ness.

From the point of view of all of these reference points, the best model is
that the chimp-human LCA is most like a chimp, and that gorillas, bonobos,
early human ancestors, and of course humans, are all different from chimps in
ways that reflect evolutionary novelties.

The chimp, in other words, is the ultimate forest ape, so well adapted to its
environment that is has changed very little. All the other species are either
close derivations of this form, or more dramatic changes, each of these
changes reflecting some environmental (or other) challenge that was, luckily,
transformed into an adaptive shift (if you like adaptations), a random change
(following relaxed selection?) or extinction. The living forms, obviously,
have not yet undergone extinction.

I remember asking a close friend of mine about the fossil record for the
chimpanzee side of the split recently; she held up her hand in the shape of a
0. Perhaps there are a few scraps, but I really hope there's a more concerted
effort to fill in the gaps on the chimpanzee side, especially since it would
either support or refute some of what you've mentioned above.

I agree that chimps, for the most part, are the best model we have for the
LCA. That being said, even though I didn't agree with Aaron Filler's mechanism
I am intrigued with his hypothesis that knuckle-walking is a derived trait and
that the LCA might have been more gibbon-like in form (which goes back to Sir
Arthur Keith).

Unfortunately fossils of the lineage leading up to chimpanzees are going to be
hard to find; if they remained in the forest taphonomy is against us, but I
think it's still important to look. Coming up with some such remains would be
a test of the modern chimpanzee as a model for the LCA and either support what
was said here or cause us to revise our ideas. Perhaps the research isn't as
"sexy" as searching for the earliest humans, but I think it's just as
important to understanding our own evolution.
==
This suborder of burrowing squamates show vestigial,
non-functional limb bones, eyes & ears.
Except for the Mexican genus Bipes, which retains its
forelimbs.
All squamate groups present problems for creationists,
of course, just as do all living things. But scaly
"reptiles" are particularly tough. The evolution of
snakes will be sorted out in coming years, as we find
more Mesozoic fossils & derive more genomes, which
have already helped resolve relationships among the
worm lizards.
I did not mean that snakes are polyphyletic but would not rule our
paraphyletic. I am saying that venomosity (and, hence, its structures) is
not a linearly evolved adaptation. Homologies between some venom proteins
are the result of the genetic adaptation of normal physiological
proteins...for example Cobra Venom Factor from the gene for C3,Bb..in a
common ancestor. The glyphic structures may not, therefore, be evolved from
each other such as aglyph->opisthoglyp h->proteroglyph- >solenoglyph. It is
my view that some of the transitional squamata between Lacertilia and
Serpentes were venomous and that some of the Mosasaurid-descende nt ancestors
of snakes were venomous. There is a tendency to view venomosity as a
recently evolved adaptation in the Reptilia but it was probably present in
the Jurassic. I have a fossil sea snake, probably a macrostomate, from the
Cretaceous but there is no way to determine if it was venomous. Extant
Hydrophiids are probably "return to the sea" species unrelated to that
fossil. The elongation of the supratemporals and quadrates and skull
structure of macrostomates suggests they ate very large prey and, unlike
recent terrestrial snakes, constriction was probably not an option with
marine prey. A snake 1-2 meters long eating prey larger in circumference
than itself, underwater, would be a perfect candidate for venomosity to
avoid injury from struggling prey. The teeth os Eupodophis are very large
for holding, much like a tree boa, but much thicker, further apart and the
final maxillary tooth appears to be more elongated. This differs from
Pachyrhachis where the dentition appears closer together and resembles that
of a boid. I think it is possible that the placement of the venom apparati
in living venomous snakes between colubroid and soleno/proteroglyph s may be
convergent.
==
From genome to "venome": Molecular origin and evolution of the snake venom
proteome inferred from phylogenetic analysis of toxin sequences and related
body proteins

ABSTRACT Top

This study analyzed the origin and evolution of snake venom proteome by means
of phylogenetic analysis of the amino acid sequences of the toxins and related
nonvenom proteins. The snake toxins were shown to have arisen from recruitment
events of genes from within the following protein families:
acetylcholinesterase, ADAM (disintegrin/metalloproteinase), AVIT, complement
C3, crotasin/ defensin, cystatin, endothelin, factor V, factor X, kallikrein,
kunitz-type proteinase inhibitor, LYNX/SLUR, L-amino oxidase, lectin,
natriuretic peptide, nerve growth factor, phospholipase A2, SPla/Ryanodine,
vascular endothelial growth factor, and whey acidic protein/secretory
leukoproteinase inhibitor. Toxin recruitment events were found to have
occurred at least 24 times in the evolution of snake venom. Two of these toxin
derivations (CRISP and kallikrein toxins) appear to have been actually the
result of modifications of existing salivary proteins rather than gene
recruitment events. One snake toxin type, the waglerin peptides from
Tropidolaemus wagleri (Wagler's Viper), did not have a match with known
proteins and may be derived from a uniquely reptilian peptide. All of the
snake toxin types still possess the bioactivity of the ancestral proteins in
at least some of the toxin isoforms. However, this study revealed that the
toxin types, where the ancestral protein was extensively cysteine
cross-linked, were the ones that flourished into functionally diverse, novel
toxin multigene families.

Venomous snakes possess one of the most sophisticated integrated weapons
systems in the natural world. The advanced snakes (superfamily Colubroidea)
make up >80% of the 2900 species of snake currently described, and contain all
of the known venomous forms (Greene 1997; Vidal 2002). Snake venom glands
evolved a single time, at the base of the colubroid radiation, 60-80 million
years ago, with extensive subsequent "evolutionary tinkering" (Vidal and
Hedges 2002; Fry and Wuster 2004). Evidence comes from comparative morphology,
embryology, and developmental biology, as well as the demonstrated homology of
venom-secreting glands of different colubroid families (Kochva 1963, 1965,
1978; Underwood and Kochva 1993; Underwood 1997; Jackson 2003), as well as the
distribution of these glands across the full spectrum of "colubrid" families
(Vidal 2002) in addition to phylogenetic analyses of toxin sequences (Fry et
al. 2003a,b; Fry and Wuster 2004). As maxillary fangs and a venom gland are a
colubroid synapomorphy, the distinction between the "Duvernoy's gland" and the
atractaspidid/elapid/viperid venom glands has been abandoned (Fry et al. 2003c).

It has been previously postulated that some of the snake toxin types (such as
three-finger toxins) evolved from a single ribonuclease ancestor (Strydom
1973). It has also been hypothesized that the snake venom gland itself evolved
in the mouth region as a consequence of an evolutionary change in the
pancreatic trait, and consequently, some of the toxins should show strong
affinities to pancreatic proteins (Kochva 1987). Therefore, a fundamental
question that has remained unanswered is what gene types were recruited for
use in the snake venom proteome and what were the tissue locations from which
these genes were harvested? Another major remaining unanswered question is
what biochemical characteristics do these ancestral proteins share?

The purpose of this study was to use phylogenetic analyses of toxin and
related body proteins to reconstruct the evolutionary history of snake venom
proteome in order to provide a frame-work for use in answering these
questions. Examined in this study were the following snake toxin types: 3FTx
(three-finger toxin), acetylcholinesterase, ADAM
(disintegrin/metalloproteinase), CVF/C3 (cobra venom factor/complement C3),
crotamine, cystatin, factor V, factor X, kallikrein, kunitoxins, L-amino
oxidase, lectins (C-type and galactose binding), MIT (mamba intestinal toxin),
natriuretic peptide, NGF (nerve growth factor), PLA2 (phospholipase A2),
sarafotoxin, SPRY (SPla/Ryanodine), VEGF (vascular endothelial growth factor),
wagerlin, and waprin (Table 1).

The conventionally recognized, major classes of a particular protein type,
characterized by activity type and specific functional motifs, formed
monophyletic groups. These groupings were congruent whether by Bayesian
analysis (Figs. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11) or maximum parsimony (data
not shown) and supported by high posterior probabilities. Of the 24 snake
toxin types examined, 23 had matches with known protein types (Table 2). In 11
data sets (acetylcholinesterase, CNP-BPP, CRISP, CVF, crotamine, factor V,
factor X, L-amino oxidase, type IB PLA2, and type IIA PLA2) the toxin
sequences were nested within a nontoxin subclade, with high posterior
probability support, thus allowing for clear inference of gene origin (Figs.
1, 2, 3, 4, 5). In seven data sets (ADAM, cystatin, MIT, kallikrein, lectin,
sarafotoxin, and SPRY), the toxin sequences formed sister groups to body
protein types with high bootstrap value support, allowing for inference of
ancestral nontoxin gene, but definitive assignment to a particular subclade
not being possible (Figs. 6, 7, 8, 9A). In five data sets (3FTx, BNP, kunitz
type proteinase inhibitor, VEGF, and waprin), high levels of saturation,
combined with short sequence length, produced polytomies that did not allow
for assignment of the toxins to specific clade within the larger protein
family (Figs. 1B, 9B, 10, 11). The waglerin toxins from Tropidolaemus wagleri
(Wagler's Viper) (Aiken et al. 1992) did not have a match with any known
protein types, and genome mining did not reveal any high confidence matches
within protein-coding regions.

Past hypotheses suggested that proteins of pancreatic origin should be the
dominant snake toxins (Strydom 1973; Kochva 1987). However, the results of
this study reveal a diverse array of tissues from which toxin encoding genes
were harvested and the bioactivities equally diverse (Tables 3, 4). While
there was no pattern with regard to specific tissue type, with many of the
ancestral gene types expressed in several tissues, all coded for secretory
proteins. Comparison of toxins and ancestral body proteins allowed for a
determination of ancestral versus derived activities (Tables 5, 6). For
example, the phylogenetic association of the 3FTx with the nicotinic
acetylcholine receptor-binding LYNX and SLUR peptides (e.g., Miwa et al. 1999;
Ibanez-Tallon et al. 2002; Chimienti et al. 2003) is consistent with the basal
-neurotoxic activity of the 3FTx (Fry et al. 2003a). This is in contrast to
previous hypotheses of an ancestral digestive action for this toxin type
(Strydom 1973).

Significant changes in the gene structure have not been currently documented
for the snake toxins relative to their protein ancestors, with the exception
of the sarafotoxins and the ADAM toxins. The gene structure of sarafotoxins is
quite distinct from that of the ancestral endothelin peptides, being arranged
in a rosary, with several coding regions in tandem (Ducancel et al. 1993). In
a highly derived form of the ADAM toxins (e.g., Q6T6T2 from Bitis gabonica),
the regions upstream of the C-terminal disintegrin domain have been excised,
and the transcripts code now solely for the disintegrin domain. The selection
pressure resulting in this change is indicative of the usefulness of this
domain to the snake in prey capture. Currently, the gene location for only one
toxin type (crotamine) has been determined, with the transcripts located at the
chromosomal tips (Radis-Baptista et al. 2003). The chromosomal location of the
endogenous ancestor crotasin (Q6HAA2) is unknown.

Molecular scaffold characteristics
Extensive cysteine cross-linking was revealed to be a beneficial
characteristic of proteins recruited for use as toxins (Table 7). Such
proteins were more likely to have come from multigene families, as well as the
toxin subgroup flourishing into a new multigene family with extensive
functional diversification. This bias is due to the stability of the molecular
core, and thus, these proteins are amenable to extensive functional
diversification. Supporting this trend, the toxin types that have been
independently recruited for use in other animal venoms are also extensively
cysteine cross-linked (Table 7).

However, the apparent bias toward mutations in the toxins of residues at the
tips of loops (Fry et al. 2003b) and lower rate of mutations of the cysteines
and flanking residues (which have structural, rather than functional roles),
may, in fact, be an arti-fact. Intracellular housekeeping enzymes are more
likely to proteolytically destroy proteins that have had a mutation of a key
structural residue, such as cysteine or a flanking amino acid. This may be a
consequence of such changes, potentially resulting in the protein being unable
to form stable tertiary conformations. Transcriptome studies may reveal more
mRNA transcripts with mutations in key structural residues than in proteins
secreted as part of the "venome."

A similar force may be at work to produce the apparent strong correlation
between extensive cysteine connectivity and the tendency for formation of
functionally diverse multigene families (Table 7). This may be due to the
beneficial stability of an extensively cysteine-linked molecular scaffold in
comparison to the much more loosely constructed tertiary structure of globular
proteins formed by noncovalent interactions. For such globular proteins, a
single amino acid change may be enough to decimate the ability of the protein
to fold into a stable conformation, and unstable proteins are once again more
likely to be destroyed by intracellular housekeeping enzymes. Thus, mutations
that may have enabled functional diversification in globular proteins may have
also produced fatal structural changes. Similarly, cDNA/EST studies may yet
again reveal more mutations in mRNA transcripts coding for globular proteins
than in secreted protein libraries.

In this study, the BNP and CNP-BPP natriuretic peptides had a high amino
acid:cysteine ratio (Table 7). The very long preproregion of the natriuretic
peptides includes a number of noncysteine-linked small peptides (e.g.,
cardiodilatin-related peptides) that are cleaved off upstream of the
circulating form of the natriuretic peptide itself. The final highly processed
form of the natriuretic peptides contains the only two cysteines coded for by
the full gene, which form the 17 amino acid loop essential for the GC-A/GC-B
receptor binding activity (Bovy 1990).

The molecular evolution of the factor X blood proteins also appeared at first
glance to be contrary to the pattern displayed by other data sets. The factor
X blood proteins are highly structurally and functionally conserved in the
body, despite being extensively cysteine cross-linked (Table 7). However, this
is a likely consequence of negative selection pressure against variations in
such a crucial aspect of hemostasis, with mutations likely to have
catastrophic effects resulting in embryonic mortality. No newly evolved
activities have been documented for the factor X toxins, possibly due to their
recent recruitment in the Australian elapid snake lineage and existing
extremely potent and useful action. However, multiple isoforms exist in each
of the venoms containing this toxin type. This is indicative of these toxins
evolving via the birth-and-death model, as has been previously shown for the
3FTx (Fry et al. 2003b). As a result, the factor X toxins may ultimately
acquire novel activities.

Potential salivary origin of two of the snake toxin types
Two of the toxin types present in the snake venome, CRISP and kallikrein, may
not actually have been the result of gene recruitment events, but rather
modifications of secreted proteins already present in the ancestral salivary
tissue that gave rise to the venom gland. Both are phylogenetically extremely
close to toxins from the venomous lizards in the Heloderma genus (Beaded
Lizards and Gila Monsters) such as Q91055 [GenBank] (helothermine) and P43685
[GenBank] (gilatoxin), respectively (Figs. 2A, 8A). The shared toxins between
the snake and Helodermatid lizard venoms represent independent recruitments of
proteins for use as toxins, as the venom-secreting structures in advanced
snakes and Heloderma lizards are different, nonhomologous structures (glands
located in the supralabial and infralabial regions, respectively), and the
last common ancestor of Heloderma and advanced snakes would have been a basal
varanoid (Forstner et al. 1995; Lee 1997) or even a basal scleroglossan
(Rieppel et al. 2003) lizard devoid of a venomous function.

In addition to the close phylogenetic relationships revealed in this study,
helothermine and gilatoxin have biochemical actions similar to the ancestral
activities of the snake venom equivalents. The snake CRISP toxins induce
hypothermia, possibly mediated through their demonstrated relaxation of the
peripheral smooth muscle through blockage of K+-induced contraction,
potentially by acting upon voltage-gated Ca2+ channels (Yamazaki et al. 2002).
Helothermine from the venomous lizard Heloderma horridum (Beaded Lizard) has
been reported to have a myriad of activities, including blocking of
voltage-gated Ca2+ channels, K+ channels and ryanodine receptors, as well as
introduction of hypothermia (Mochca-Morales et al. 1990; Nobile et al. 1994,
1996; Morrissette et al. 1995). The isolation of toxins with the same action
(relaxation of smooth muscle and induction of hypothermia) from divergent
groups of snakes, as well as the unrelated venomous lizards, indicates that
this may be the original activity of the common protein ancestor. Similarly,
both the snake and lizard kallikrein toxins are sister groups to the mammalian
tissue (glandular) kallikrein, secreted in a wide variety of tissues including
saliva glands (Fig. 8A). Gilatoxin also displays significant similarity of
action to the snake venom equivalents, releasing bradykinin from kininogen
with subsequent lowering of blood pressure (Utaisincharoen et al. 1993).

Clearly, in either case, the snake and lizard toxins were recruited from
closely related body proteins, reflective of the wide-spread presence of CRISP
and kallikrein proteins in salivary tissue and other exocrine tissue. In light
of the strong phylogenetic associations, the similarity of bioactivities and
the relationship to known salivary proteins, the most parsimonious explanation
is that both toxin types are derivations of previously existing salivary
proteins. Sequencing and phylogenetic analysis of both protein types from
nontoxin-secreting salivary tissue from venomous and nonvenomous lizards and
snakes would be revealing in this context.

Presence of snake toxin types in other animal venoms
In addition to the presence of CRISP and kallikrein in lizard venoms, other
protein types have been independently selected for use as toxins by other
venomous animals.

Disparate members of the protein superfamily to which the CRISP proteins
belong are used in venoms of cone snails, such as Q7YT83 from Conus textile
(Cloth-of-gold cone snail) and insects, such as P10736 [GenBank] from
Dolichovespula maculata (White-face hornet) and P35778 [GenBank] from
Solenopsis invicta (Fire ant). However, the activities of these toxins differ
considerably from the reptilian CRISP toxins. The toxin from Conus textile has
a proteinase activity, while the insect toxins are the major venom allergens.
Interestingly, CRISP-related proteins are also the major allergens in insect
saliva, such as Q9NH66 from Ctenocephalides felis (Cat flea), Q7Z0B5 from
Stomoxys calcitrans (Stable fly), and Q8T9U1 from Aedes aegypti (Yellowfever
mosquito). Intriguingly, CRISP-related proteins are also utilized by plants
for defence against fungi (e.g., PR-1 protein P35792 [GenBank] from Hordeum
vulgare [Barley]), and other proteins are the hallmark of certain cancer types
(e.g., the glioma pathogenesis-related protein P48060 [GenBank] ). None of
these other CRISP-related proteins align near the snake or lizard venom toxins
(Fig. 2A).

The PLA2 proteins have also been recruited on numerous occasions, ranging from
Q7M4I5 from Apis dorsata (Giant honeybee), Q8WS88 from Adamsia carciniopados
(Cloak Sea Anemone), and P80003 [GenBank] from Heloderma suspectum (Gila
Monster) venoms, with a wide variety of evolved activities. It is notable that
the PLA2 from Heloderma venoms are not biochemically or phylogenetically
related to either of the snake PLA2 toxin types, reinforcing the uniqueness of
the relationships of the CRISP and kallikrein toxins.

Intriguingly, the kunitz peptides in sea anemone venom have been convergently
evolved for the same unique K+ channel-blocking activity as the highly derived
Dendroaspis (Mamba) venoms within the Elapidae snake family (Schweitz et al.
1994, 1995). Ornithorhynchus anatinus (Platypus) venom contains high amounts
of CNP natriuretic toxins (e.g., de Plater et al. 1998a,b), but of a form that
lacks the derived BPP domains found in the snake brain and venom peptides.

Two snake toxin types have been independently recruited for use in amphibian
toxic skin secretions. The AVIT peptides on frog skin have a similar toxic
action as the snake MIT toxins, causing intestinal cramping and increased
sensitivity to pain (Mollay et al. 1999). AVIT-like peptides have also been
reported from spider venoms (Szeto et al. 2000), but other than sharing the
cysteine arrangement, the arachnid toxins lack all of the invariant residues,
as well as the contractive effect upon smooth muscle and the ability to
produce hyperalgesia. Toxins related to the snake venom 3FTx are secreted on
the skin of Xenopus laevis (African clawed frog) (e.g., Q09022 [GenBank] ).
These toxins are phylogenetically and functionally distinct from the snake
venom 3FTx, acting presynaptically by activating dihydropyridine-sensitive
Ca2+ channels (Kolbe et al. 1993). These toxins appear to be wide-spread in
amphibians, with related peptides (e.g., Q71TU4) having been sequenced from
the skin of Plethodon jordani (Jordan's salamander).

Notably, all of the above shared toxin types are extensively cysteine
cross-linked, come from functionally diverse multigene families, and all have
been developed into toxin multigene families (Table 7). The multiple,
independent recruitment of certain protein types for use as toxins also sheds
additional light on what sorts of proteins are favored in molecular evolution
and what sort of molecular scaffold is beneficial. However, unlike the
Heloderma CRISP and kallikrein toxins, they are all phylogenetically very
distinct from the snake equivalents. This reinforces the uniqueness of the
close relationship between the snake and lizard CRISP and kallikrein toxins
and the most parsimonious explanation of these two toxin types arising from
modification of existing salivary proteins.

Conclusion
The results of this study suggest that the tissue types from which the toxin
recruitment genes were selected were as diverse as the proteins themselves.
Two toxin types (CRISP and kallikrein) actually appear to be modifications of
proteins already present in the ancestral salivary tissue. While the activity
of the ancestral protein has been invariably retained, toxin types originating
from extensively cysteine cross-linked proteins have been the ones to flourish
into newly derived, functionally diverse, toxin multigene families.

In order to minimize confusion, all proteins' sequences are referred to by
their SWISS-PROT accession numbers
(http://www.expasy.org/cgi-bin/sprot-search-ful). Sequences were obtained
through BLAST searching using representative toxin sequences
(http://www.expasy.org/tools/blast/). Resultant sequence sets were aligned
using the program CLUSTAL-X (Thompson et al. 1997), followed by visual
inspection for errors. In the cases where peptides have been incorporated as
domains into longer preproteins (Kunitz protease inhibitors, whey acidic
protein, and SPRY), alignments were trimmed on either side of the domain. Due
to the large number of sequences in each data set, phylogenetic analyses were
conducted in two steps. For each data set, phylogenetic trees containing all
sequenced proteins were initially reconstructed using the maximum parsimony
(MP) method, conducted using the program PAUP*4.0b10 (Swofford 2002) and
random stepwise taxon addition with TBR branch swapping and the PROTPARS
weighting scheme (Felsenstein 2001), which takes into account the number of
changes required at the nucleotide level to substitute one amino acid for
another. Number of sequences, alignment length (including gaps), and parsimony
informative sites are shown in Table 1. In this manner, clades that contained
the venom proteins were identified. Once such clades were identified, data
sets containing representative venom proteins, all the nearest neighbor
nonvenom sequences, and representatives of the full breadth of gene
phylogenetic diversity were selected and then analyzed using Bayesian
inference implemented on MrBayes, version 3.0b4 (Huelsenbeck and Ronquist
2001; Ronquist and Huelsenbeck 2003). The method uses Markov-chain Monte Carlo
methods to generate posterior probabilities for each clade represented in the
tree. The analysis was performed by running a minimum of 1*106 generations in
four chains, and saving every 100th tree. The log-likelihood score of each
saved tree was plotted against the number of generations to establish the
point at which the log likelihood scores of the analysis reached their
asymptote, and the posterior probabilities for clades established by
constructing a majority rule consensus tree for all trees generated after the
completion of the burn-in phase. Sequence alignments and unrooted maximum
parsimony trees can be obtained by e-mailing Dr. Bryan Grieg Fry

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[Abstract] [Full Text] [PDF]


==
Evolution is descent with modification. Random changes in the genetic makeup
of an organism result in changes in the phenotype. The organism interacts with
its environment. If the changes to the phenotype give it an advantage over
others - the vast majority of genetic changes are deleterious -- it leaves
more offspring, who are also endowed with this advantageous genetic makeup for
dealing with their environment. This latter is known as "natural selection."
This simple but powerful process leads to new species through separation of
organisms in time and place.
==
THREE years before his death in 1805, English philosopher William Paley
proposed a now-famous thought experiment. Imagine discovering a watch on the
heath: how would you explain its intricate arrangement of parts, its clear
design for a purpose? Naturally, you'd conclude that it was built by a
watchmaker, not blown together by chance. By analogy, Paley argued, the
natural world is full of designed complexity which must therefore also have a
creator: God.
Had Paley been in a position to know about it, he would no doubt have
considered a remarkable little device called the bacterial flagellum to be an
excellent example of designed complexity. With its intricate arrangement of
interconnecting parts, the flagellum looks no less designed than a watch, and
would surely have had Paley reaching for the existence of its "maker".
Modern biology, of course, has no need for omniscient designers. Evolution -
Richard Dawkins's blind watchmaker ...
==
Bats flew before they had 'radar'
NEW YORK  A fossil found in Wyoming has apparently resolved a long-standing
question about when bats gained their radar-like ability to navigate and
locate airborne insects at night. The answer: after they started flying.
The discovery revealed the most primitive bat known, from a previously
unrecognized species that lived some 25.5 million years ago.
Its skeleton shows it could fly, but that it lacked a series of bony features
associated with "echolocation," the ability to emit high-pitched sounds and
then hear them bounce back from objects and prey, researchers said.
Until now, all the early known fossil bats showed evidence of both flying and
echolocating, so they couldn't reveal which ability came first, said
researcher Nancy Simmons.
Her team's research appears in Thursday's issue of the journal Nature. Simmons
chairs the vertebrate zoology division at the American Museum of Natural
History in New York.
The early bat's wingspan was nearly a foot, just a bit smaller than that of
today's big brown bat, she said. Its teeth show it ate insects, which it
evidently plucked off surfaces after seeing, smelling or hearing them, she
said. Simmons said she suspects the bat was active at night, but she noted
there's no evidence for that.
The creature was unusual for having a claw on all five fingers rather than
just one or two. Researchers dubbed it "Onychonycteridae finneyi," meaning
"clawed bat." The name honors Bonnie Finney, the commercial collector who
found the fossil in 2003.
Two specimens of the creature have been recovered. "These outstanding fossils
considerably advance our understanding of bat evolution," researcher John
Speakman of the University of Aberdeen in Scotland wrote in a Nature
commentary.
==
An example is the Zebra 
Longwing butterfly, which feeds on only one small group of closely 
related plants. They genetically recognize these plants, probably 
by their chemical odors, and lay their eggs solely on these. 
==
A fossil of a new crab species reveals the itsy-bitsy crustaceans inhabited
towering sponge reefs during the Jurassic Period, where they made tasty snacks
for ichthyosaurs and other ancient reptiles.
The fossil was discovered in eastern Romania within cylindrical reef
structures about 100 feet (30 meters) across and just as tall, which were once
blanketed by deep ocean. It represents a new species within the oldest lineage
of true crabs that lived 150 million years ago when dinosaurs walked the Earth.
Dubbed Cycloprosopon dobrogea, the primitive crab was built for sidling in and
out of crevices in reefs, with a flattened body just under a half-inch (6
millimeters) long. Exactly how the crab moved about, however, is not known, as
this species and other family members had no legs extending from the carapace,
or outer body covering.
"They probably were hiding in the small cracks and crevices within the sponge
reef itself," said lead researcher Carrie Schweitzer, a geologist at Kent
State University in Ohio.
The underwater hideouts would've proved critical to survival in the face of
ancient reptiles nosing around for tasty morsels.
"These crabs in the Jurassic were living in much deeper water than a dinosaur
would've been, but something like an ichthyosaur or a plesiosaur would
certainly have been eating crabs," Schweitzer told LiveScience.
Schweitzer has uncovered other Jurassic crabs in this area and elsewhere,
indicating, she says, that the crustaceans were much more diverse and
plentiful than scientists had thought.
==
Evolution describes an active response to the environment but it is passive.
Because variation exists within a species, the environment both biotic and
abiotic decide the shape of an organism. The forces in the world are not
random. It is wetter on the coast, dryer in the interior, colder towards the
poles, hotter towards the equator. If you took a zoo and emptied half its
contents into an equatorial rainforest and the other half on the arctic tundra,
you would quickly see how the environment will select those that have the
necessary structure and behavior to survive. 
Putting something in mathematical terms does not make it correct. Any work must
ultimately be reviewed by other scientists with necessary background. It is not
a perfect system but it is a lot better than teaching as science anything that
enters the public fancy. 
==
Origin of Vision Discovered
You are reading these words right now because 600 million years ago, an
aquatic animal called a Hydra developed light-receptive genesthe origin of
animal vision.
It wasn't exactly 20-20 vision back then though.
Hydras, a genus of freshwater animals that are kin to corals and jellyfish,
measure only a few millimeters in diameter and have been around for hundreds
of millions of years.
Scientists at the University of California, Santa Barbara studied the genes
associated with vision (called opsins) in these tiny creatures and found opsin
proteins all over their bodies.
Though they don't have eyes or any specific light-receptive organs,
researchers think that the light-sensing proteins concentrated in the mouth
area of the Hydras help them to use light sensitivity to search out prey.
Because studies of animals that evolved earlier, such as sponges, don't show
the same light sensitivity, scientists were able to pinpoint the Precambrian
date that animal vision first started to evolve.
"We now have a time frame for the evolution of animal light sensitivity," said
study leader David Plachetzki, a UC Santa Barbara graduate student. "We know
its precursors existed roughly 600 million years ago.
These findings, detailed in a recent issue of the online journal PLoS ONE,
counter arguments by anti-evolutionists that evolution can only eliminate
traits and cannot produce new features, the authors say.
Our paper shows that such claims are simply wrong," said co-author Todd
Oakley, also a UC Santa Barbara biologist. "We show very clearly that specific
mutational changes in a particular duplicated gene (opsin) allowed the new
genes to interact with different proteins in new ways. Today, these different
interactions underlie the genetic machinery of vision, which is different in
various animal groups.
==
 Origin of Apes
Humans are great apes and are one of the species in the family Hominidae along
with only a few other species. The Hominidae include two distinct species of
the genus Pan: Pan paniscus (bonobos) and Pan troglodytes (chimpanzees), two
species of gorillas (Gorilla gorilla and Gorilla graueri), and two species of
orangutans (Pongo pygmaeus and Pongo abelii).
Apes in turn belong to the Primates order (>375 species). Data from both
mitochondrial and nuclear DNA indicates that primates belong to the group of
Euarchontoglires, together with Rodentia, Lagomorpha, Dermoptera, and
Scandentia.[1] This is further supported by Alu-like SINEs which have been
found only in members of the Euarchontoglires.
===
Evolution is the process by which survivors will adapt to changed
circumstances, or go extinct.
==
Both eutherian cats and metatherians have evolved
saber-toothed species. the saber-toothed marsupials had oversized incisors
and the saber-toothed cat's saber teeth were canines. A pair of big sharp
teeth seems to be the only
commonality, and that characteristic only emerges because the theria, as a
group, had differentiated teeth. When you take a Cretaceous era predator which
also fed on prey much larger than itself, you see something like Velociraptor,
which had a enlarged claw, rather than saber teeth, because the teeth of
Velociraptor were not very differentiated. Here again, different evolutionary
trajectories produce different solutions to the same problem.
===
Some exquisitely fine studies of microanatomy  suggests the brain of amphioxus
has regions equivalent to the tripartite division seen in the vertebrates.
==
http://fm1.fieldmuseum.org/aa/Files/patterso/Dick___Patterson_2006_MicromammalsMacroparasites.pdf
bat flies
==
Ruse. LIFE'S SOLUTION

Steven Johnson's 'Emergence: The Connected Lives of Ants, Brains, Cities, and
Software.'

Wesson  "Beyond Natural Selection"

Ryan "Dawin's Blindspot" 

Simon Conway Morris  "Life's Solutions" 

The Emergence of Everything: How the World Became Complex (Paperback) 
by Harold J. Morowitz (Author)
==
Piltdown Man claim was made by Mr. Charles Dawson at Piltdown,
Sussex, between the years 1911 and 1915. He "found" the greater part of the
left half of a deeply mineralized human skull, also part of the right half; the
right half of the lower jaw, damaged at certain parts but carrying the first
and second molar teeth and the socket of the third molar or wisdom tooth.
After much controversy, it turned out to be not a primitive man at all, but a
composite of a skull of modern man and the jawbone of an ape. ... The jawbone
had been 'doctored' with bichromate of potash and iron to make it look
mineralized."
===
The Counter-Creationism Handbook by Mark Isaak
Michel Onfray   In Defence of Atheism 

All the changes to human evolutionary thought should not be considered a
weakness in the theory of evolution, Kimbel said. Rather, those are the
predictable results of getting more evidence, asking smarter questions and
forming better theories, he said. 
==
ORIGINS: A Skeptic's Guide to the Creation of Life, by Robert Shapiro,
===
------------------------------------------------------------------------
How Giant Dinosaurs Survived Vulnerable Youth
Titanosaurs were among the largest creatures to ever walk the Earth, with some
gargantuan examples believed to have weighed more than 100 tons. Bony scales
dotted their hides, but their purpose remained a mystery.
Analysis of titanosaur embryos suggest these scales helped protect the giants
during their vulnerable youth, guarding them against predators.
Paleontologist Thiago Marinho at the Federal University of Rio de Janeiro
analyzed data on titanosaur eggs discovered in Patagonia in Argentina in 1997.
The embryos within had evidence of skin that bore a number of bumps. Comparison
with skin patches seen in alligator embryos suggested the dinosaur bumps might
one day toughen up into bony scales known as osteoderms.
The osteoderms seen on adult titanosaurs were too small and spongy to provide
much real defense. Marinho noted such body armor would have been far more
effective for young titanosaurs than adults, protecting against the bites of
marauders such as theropodscarnivorous dinosaurs that included T. rexas well
as crocodile-like predators known as crocodyliforms.
Such armor would have proven especially helpful for young titanosaurs, since
no fossil evidence exists that titanosaurs displayed much in the way of
parental care, Marinho added.
"Although the titanosaurs comprise some of the biggest land animals to walk on
Earth, we have to keep in mind that they were born from eggs 30 centimeters [12
inches] in diameter," Marinho said. While such eggs might be huge by modern
standards, the 1-foot-long or so hatchlings resulting from them "wouldn't
stand a chance against big theropod dinosaurs. But they might have had an
effective defense system against small theropods and terrestrial
crocodyliforms if they had a cuirass [protective covering] composed by
side-by-side osteoderms."
Marinho figures that as titanosaurs grew, they absorbed as much calcium as
they could to form their massive skeletons, including from their osteoderms,
making these bony scales more porous and spongy.
"Extant crocodilians, especially juveniles and young adults, do absorb calcium
from their osteoderms when their diets do not supply the calcium demand for
their metabolism," he explained. As the dinosaurs grew older, the bony scales
"would have become obsolete accessories, as the size of the titanosaurs was
itself a defense system."
Other dinosaurs were known to have possessed bony scales as well, such as the
predatory theropod Carnotaurus. While scant fossil evidence of young or
embryonic theropod skin has been found as yet, the notion that juvenile
theropods might have had bony scales to protect them"can't be discarded,"
Marinho said.
==
"Hypercycles and the origin of life" nature, vol 280 pp445-46. 
reprinted in Maynard Smith 1982, pp34-38
==
http://www.fieldmuseum.org/   Great  long
==
David Sloan Wilson. Evolution  can also be applied to almost every aspect of
human life,  as he demonstrates in his first book for a general audience,
Evolution for Everyone: How Darwin's Theory Can Change the Way We Think About
Our Lives (Bantam Press 2007).
==
Rev Sun Myung Moon paid for Wells to get a college degree
so he would have some "authority" when criticizing evolution.
==
In a 1999 interview with Insight Magazine, Johnson explained why he singled
out evolution when his real target was all of modern science: "Evolution is a
creation story and as a creation story, it's the main prop of the materialist
explanation for our existence."
==
In the physical sciences, abiogenesis, the question of the origin of life, is
the study of how life on Earth might have emerged from non-life sometime
between 4.4 billion years ago, when liquid water first flowed on the Earth,
and 2.7 billion years ago when the earliest uncontroversial evidence of life is
found in the form of stable isotopes[1][4] and molecular biomarkers pointing to
photosynthesis.
==
A list" of endangered species, however, lists 784 species driven to
extinction since 1500--ranging from the dodo bird of Mauritius to the golden
toad of Costa Rica. 
==
Since you claim to have heard of fossils, are you aware
that the sequence of fossils found pretty much anywhere 
on Earth looks like this (thanks to Matt):

first bacteria below
first multicellular organism below
first shelled organisms below
first insects below
first amphibians below
first reptiles below
first dinosaurs below
first birds below
first placental mammals below
first apes below
first hominids

Evolution has an explanation for this.

Creationism does not.
==
http://www.milleran dlevine.com/ km/evol/DI/ clot/Clotting. html
==
Discovery of new species of fish gives evolution clues
BEIJING, May 7 (Xinhua) -- A Chinese research team has discovered four fossils
of a new species of fish dating back 400 million years which may provide clues
to the evolution of fish.
Dr. Zhu Min, the leading scientist from the Chinese Academy of Sciences (CAS)
Institute of Vertebrate Paleontology and Pale anthropology, said Sunday that
the newly discovered species may represent a bridge between two vertebrate
lineages that ultimately went on to dominate the modern world.
The find made by Zhu and his colleagues was published in the latest issue of
the British journal Nature.
The fossilized creature, found in southwest China's Yunnan Province, combines
features shown by ray-finned bony fishes, including the majority of modern
fish species, and by lobe-finned bony fishes, the group that spawned the
ancestors of today's land vertebrates, Dr. Zhu said.
The ancient fish, represented by chunks from four separate skulls, has a skull
roof much like that of actinopterygian, the group that includes most modern
fish, Dr. Zhu said.
But the fine features of its anatomy may also shed light on the evolutionary
origin of cosmine - a hard surface-tissue found in many fossil
sarcopterygians, the fish that later gave rise to land vertebrates, he said.
Cosmine is characterized by a network of pores and canals in the tissue,
overlaid by a single enamel-based layer, Zhu explained.
The 405 million-year-old fossil possessed several such layers over the
pore-canal network, suggesting that the cosmine arose after all but one of
these layers disappeared, he said.
Zhu named the ancient fish after his mentor, Prof. Meemann Chang, China's most
prominent paleontologist and also a CAS member. Prof. Chang laid the foundation
of modern research on ancient bony fishes.
With the latest find, Dr. Zhu and his team are trying to prove that
lobe-finned bony fishes originated from south China.
==
160,000-Year-Old Child Suggests Modern Humans Got Early Start
Bucking conventional wisdom, a new study says early members of our species,
Homo sapiens, may have known what it was like to be a kid.
A long childhood is considered one of things that separate so-called modern
humans from the first Homo sapiens and older human species, such as Homo
erectus.
Now a study of a 160,000-year-old early Homo sapiens child found in North
Africa may change how earlyand wherewe think modern humans arose.
A Study With Teeth
European researchers used x-ray imaging to study the growth patterns of teeth
in the juvenile fossil found in Morocco. Similar to tree rings, the patterns
are a record of aging.
What they revealed is that this fossil is the earliest known human with a long
childhood, according to Tanya Smith, an anthropologist at the Max Planck
Institute for Evolutionary Anthropology in Germany.
In the teeth the scientists found signs of modern-human development
patternsthat is, relatively long periods of slow development and growth. A
prolonged childhood is seen as necessary for the type of learning that leads
to culture and complex society.
The juvenile fossil "showed an equivalent degree of tooth development to
living [modern] human children at the same age," the report authors write.
According to the researchers, the study challenges theories about when and
where humans acquired modern bodies and behaviors.
The findings also may help prove that "modern biological, behavioral, and
cultural characteristics" were relative latecomers in the past six million
years of human evolution.
"These findings are in contrast to studies that suggest that earlier fossil
hominins [humans and our ancestral species] possessed short growth periods,
which were more similar to chimpanzees than to living humans," the study
authors write in this week's issue of the journal Proceedings of the National
Academy of Sciences.
Study co-author Smith said her research team knew that human ancestors living
several million years ago grew up differently from modern children.
"What we didn't know was when the modern human condition of a long childhood
and slow period of growth and development evolved," she said.
The study suggests that developmentally modern humans existed at least 160,000
years ago, which Smith says is just slightly younger than the earliest fossil
Homo sapiens from East Africa.
Promising New Method
"It is a great result that today we can really measure growth rates of teeth
due to CT [and] x-ray technology," said Professor Ottmar Kullmer, a
paleoanthropologist at the Research Institute Senckenberg in Germany.
"These new possibilities of modern analysis methods augment the understanding
of early Homo sapiens development and human evolution in general."
Kullmer, who was not a participant in the study, said that the discovery of a
relatively long human childhood about 160,000 years ago points to "a complex
social system in early Homo sapiens groups."
"Probably, social behavior was one of the important survival strategies of
early humans."
==
Learn the controversy: sympatric versus allopatric speciation
When one looks carefully at a biological problem, one can usually discover
more than one casual explanationIndeed, it is quite possible that in biology
the majority of phenomena and processes must be explained by a plurality of
theories.
Ernst Mayr This is Biology (1997)
One long standing controversy in evolutionary biology is about the respective
contributions sympatry and allopatry have made during the origins of the
millions of species that now exist.
A new species (or 2 new species) can develop if gene flow between 2
populations ceases or slows down to permit the independent evolution of the 2
populations.
Allopatric (or geographic) speciation takes place when 2 populations are
geographically isolated from each other by, for example, a mountain chain, or
an ocean. Because the members of the 2 populations cannot mate and exchange
genes with each other, the populations may start to diverge genetically and
phenotypically and eventually end up being 2 separate species. In extreme
cases of allopatry, there will be no gene flow between the diverging
populations.
The opposite of this is sympatric speciation, which takes place in 2
populations whose distribution ranges are largely overlapping. Individuals
initially belonging to the same species may begin to differentiate from each
other when they start eating different foods or living in different habitats.
If the slight genetic differences that may exist between such individuals are
reinforced by assortive mating1, 2 populations may emerge and begin to diverge
genetically and phenotypically to eventually become separate species. New
species may originate even when there is some gene flow between the 2
populations.
An intermediate mechanism is parapatric speciation, which takes place in
contiguous, but otherwise geographically isolated (allopatric) populations.
G.G. Simpson. 1983. Fossils and the History of Life. Scientific
American Books.
The late Ernst Mayr was a strong proponent of allopatric speciation and for
most of his long career, he discounted sympatric speciation as a viable
mechanism. However, an increasing number of studies have been demonstrating
that sympatric speciation is possible and may have taken place more often than
traditionally believed.
A well-written short essay by Chris D. Jiggins2 in the 9 May issue of Current
Biology reviews some recent studies and presents a good argument in favor of
sympatric speciation, while pointing out that the usual division of speciation
events along a strict line as either sympatric or allopatric creates an
artificial dichotomy. In line with Mayrs opinion about the necessity to
explain biological processes by more than one theory, Jiggins suggests that in
most cases of speciation, sympatric and allopatric processes may both have been
reponsible.
allopatric and sympatric speciation lie at the opposite ends of a continuum,
which runs from zero to maximal gene flow between diverging populations. These
new studies provide good evidence that fully sympatric speciation can occur,
but most examples probably lie somewhere in between these two extremes.
As is usually the case with any genuine scientific controversy, this one will
continue to inspire further research and lead to better understandings of the
many-faceted speciation
==
Gavin de Beer and mosaic evolution
In a broad sense, all organisms can be said to be mosaics, with some
characteristics so ancient in origin that they have changed little and some so
recent, geologically speaking, that they have changed more than a little. It
rarely occurs to most of us that we share ancestral characters with such
different organisms as, for example, a flowering shrub.

On this date in 1972 the English evolutionary biologist Sir Gavin R. de Beer
died (born 1899). One lasting contribution of de Beer to evolutionary theory
was the concept of mosaic evolution that he developed in a 1954 paper1.
Although a mosaic-like pattern of evolution is becoming more and more apparent
in many major evolutionary transitions, including the evolution of humans from
ape-like ancestors, I have not been able to find a recent general review of
what mosaic evolution is all about. Stebbins published a review in 1983, but
he seems to have confused mosaic evolution with adaptive radiation2. Recently,
Mayr3 and earlier, Simpson4 gave brief explanations of the concept with both
authors properly distinguishing mosaic evolution from adaptive radiation.
Curiously, Ridleys textbook on evolution5 doesnt mention mosaic evolution at
all.
To my great satisfaction, however, I have found in de Beers succinctly written
original paper a full explanation of his idea.
As the title of his paper implies, de Beer derived the concept of mosaic
evolution from his study of the fossil Archaeopteryx and by comparing it with
the bones of reptiles and birds. He found that Archaeopteryx had both
reptilian and avian features:
All these are characters which would not be in the least out of place if found
in any reptile. On the other hand, there are a number of features in
Archaeopteryx which are absolutely characteristic of birds
This comparison led him to conclude that
it is clear that Archaeopteryx provides a magnificent example of an animal
intermediate between two classes, the reptiles and the birds, with each of
which it shares a number of well-marked characters.
And this led to the formulation of mosaic evolution (content in brackets mine):
the statement that an animal was intermediate might mean that it was a mixture
and that the transition affected some parts of the animal and not others, with
the result that some parts were similar to those of one type [ancestor], other
parts similar to the other type [descendant], and few or no parts intermediate
in structure. In such a case the animal might be regarded as a mosaic in which
the pieces could be replaced independently one by one, so that the transitional
stages were a jumble of characters some of them similar to those of the class
from which the animal evolved, others similar to those of the class into which
the animal was evolving.
He then applied these ideas to the fossils exemplifying the transitions from
fish to amphibian and from amphibian to reptile and finally, from reptile to
mammal. In each case, his observations derived from specific examples can be
turned into general statements of mosaic evolution.
But the fact that an animal can be at one and the same time show so many
features which would make it an ideal transitional form, and also spoil this
picture by possessing one or two characters which rule it out as a direct
ancestor, is itself an argument in support of the principle of mosaic
evolution, with the different pieces evolving separately, and some of them too
fast. This phenomenon is found again and again in the study of transitions from
one type of animal to another, and appears to be of general applicability. It
would be more difficult to understand if the transitions took place by a
gradual and simultaneous conversion of all the parts of the animal.
This was followed by the notion of the evolution of different organs at
different rates:
Just as in some casesan animal may show characters which have evolved too fast
relatively to the other characters, in other cases certain characters may have
been left in a profoundly archaic condition.
De Beer even dealt preemptively with potential objections to his idea:
Organisms are delicately balanced and adjusted mechanisms, and on the average,
changes are more likely to upset than to strengthen them. Selection may
therefore be expected to have acted with greater rigour against organisms
vaying in more than one direction at a time, unless the directions were
correlated
All of this terminated in a final conclusion:
A necessary consequence of mosaic evolution and of the independence of
characters evolving at different rates is the production of animals showing
mixtures of primitive and specialised characters.
A technical paper discussing de Beers significant accomplishments in
embryology.
Some recent technical papers on mosaic evolution:
Andrew N. Iwaniuk, Karen M. Dean, John E. Nelson. 2004. A mosaic pattern
characterizes the evolution of the avian brain. Proceedings: Biological
Sciences 271, S148151.

Robert A. Barton and Paul H. Harvey. 2000. Mosaic evolution of brain structure
in mammals. Nature 405, 1055-1058.

Todd C. Rae. 1999. Mosaic Evolution in the Origin of the Hominoidea. Folia
Primatol 70:125135
1. De Beer, G.R. 1954. Archaeopteryx and evolution. Advancement of Science
11:160-170.
2. Stebbins, G.L. 1983. Mosaic evolution: an integrating principle for the
modern synthesis.
Experientia 39:823-834.
3. Mayr, E. 2001. What evolution is. Basic Books.
4. Simpson, G.G. 1983. Fossils and the history of life. Scientific American
Books.
5. Ridley, M. 1996. Evolution. 2nd ed. Blackwell.

==
Chimpanzees 'hunt using spears'
Chimpanzees in Senegal have been observed making and using wooden spears to
hunt other primates, according to a study in the journal Current Biology.
Researchers documented 22 cases of chimps fashioning tools to jab at smaller
primates sheltering in cavities of hollow branches or tree trunks.
The report's authors, Jill Pruetz and Paco Bertolani, said the finding could
have implications for human evolution.
Chimps had not been previously observed hunting other animals with tools.
Pruetz and Bertolani made the discovery at their research site in Fongoli,
Senegal, between March 2005 and July 2006.
"There were hints that this behavior might occur, but it was one time at a
different site," said Jill Pruetz, assistant professor of anthropology at Iowa
State University, US.
"While in Senegal for the spring semester, I saw about 13 different hunting
bouts. So it really is habitual."
Chimpanzees were observed jabbing the spears into hollow trunks or branches,
over and over again. After the chimp removed the tool, it would frequently
smell or lick it.
In the vast majority of cases, the chimps used the tools in the manner of a
spear, not as probes. The researchers say they were using enough force to
injure an animal that may have been hiding inside.
However, they did not photograph the behaviour, or capture it on film.
Adolescent females exhibited the behaviour most frequently (Image: M Gaspersic)
In one case, Pruetz and Bertolani, , from the Leverhulme Centre for Human
Evolutionary Studies in Cambridge, UK, witnessed a chimpanzee extract a
bushbaby with a spear.
In most cases, the Fongoli chimpanzees carried out four or more steps to
manufacture spears for hunting.
In all but one of the cases, chimps broke off a living branch to make their
tool. They would then trim the side branches and leaves.
In a number of cases, chimps also trimmed the ends of the branch and stripped
it of bark. Some chimps also sharpened the tip of the tool with their teeth.
Adult males have long been regarded as the hunters in chimp groups.
But the authors of the paper in Current Biology said females, particularly
adolescent females, and young chimps in general were seen exhibiting this
behaviour more frequently than adult males.
"It's classic in primates that when there is a new innovation, particularly in
terms of tool use, the younger generations pick it up very quickly. The last
ones to pick up are adults, mainly the males", said Dr Pruetz, who led the
National Geographic-funded project.
This is because young chimps pick the skill up from their mothers, with whom
they spend a lot of their time.
"It's a niche that males seem to ignore," Dr Pruetz told BBC News.
Many areas where chimpanzees live are also home to red colobus monkey, which
the chimps hunt. However, the Senegal site is lacking in this species, so
chimps may have needed to adopt a new hunting strategy to catch a different
prey - bushbaby.
The authors conclude that their findings support a theory that females may
have played a similarly important role in the evolution of tool technology
among early humans.
==
http://en.wikipedia .org/wiki/ Micelle
Micelles are phospholipid layers that form spontaneously in polar 
liquids such as water. If this sounds familiar, it is because plasma 
membranes of cells consist of phospholipid bilayers. The probability 
of phospholipid bilayers forming in water is 1. It happens every 
time. Pretty easy math.
===
Lactose Tolerance in East Africa Points to Recent Evolution
A surprisingly recent instance of human evolution has been detected among the
peoples of East Africa. It is the ability to digest milk in adulthood,
conferred by genetic changes that occurred as recently as 3,000 years ago, a
team of geneticists has found.
The finding is a striking example of a cultural practice  the raising of dairy
cattle  feeding back into the human genome. It also seems to be one of the
first instances of convergent human evolution to be documented at the genetic
level. Convergent evolution refers to two or more populations acquiring the
same trait independently.
Throughout most of human history, the ability to digest lactose, the principal
sugar of milk, has been switched off after weaning because the lactase enzyme
that breaks the sugar apart is no longer needed. But when cattle were first
domesticated 9,000 years ago and people later started to consume their milk as
well as their meat, natural selection would have favored anyone with a mutation
that kept the lactase gene switched on.
Such a mutation is known to have arisen among an early cattle-raising people,
the Funnel Beaker culture, which flourished 5,000 to 6,000 years ago in
north-central Europe. People with a persistently active lactase gene have no
problem digesting milk and are said to be lactose tolerant.
Almost all Dutch people and 99 percent of Swedes are lactose tolerant, but the
mutation becomes progressively less common in Europeans who live at increasing
distances from the ancient Funnel Beaker region.
Geneticists wondered if the lactose tolerance mutation in Europeans,
identified in 2002, had arisen among pastoral peoples elsewhere. But it seemed
to be largely absent from Africa, even though pastoral peoples there generally
have some degree of tolerance.
A research team led by Dr. Sarah Tishkoff of the University of Maryland has
now solved much of the puzzle. After testing for lactose tolerance and genetic
makeup among 43 ethnic groups in East Africa, she and her colleagues have found
three new mutations, all independent of one another and of the European
mutation, that keep the lactase gene permanently switched on.
The principal mutation, found among Nilo-Saharan-speaking ethnic groups of
Kenya and Tanzania, arose 2,700 to 6,800 years ago, according to genetic
estimates, Dr. Tishkoffs group reports today in the journal Nature Genetics.
This fits well with archaeological evidence suggesting that pastoral peoples
from the north reached northern Kenya about 4,500 years ago and southern Kenya
and Tanzania 3,300 years ago.
Two other mutations were found, among the Beja people of northeastern Sudan
and tribes of the same language family, Afro-Asiatic, in northern Kenya.
Genetic evidence shows that the mutations conferred an enormous selective
advantage on their owners, enabling them to leave almost 10 times as many
descendants as people without such mutations. The mutations have created one
of the strongest genetic signatures of natural selection yet reported in
humans, the researchers write.
The survival advantage was so powerful perhaps because those with the
mutations not only gained extra energy from lactose but also, in drought
conditions, would have benefited from the water in milk. People who were
lactose intolerant could have risked losing water from diarrhea, Dr. Tishkoff
said.
Diane Gifford-Gonzalez, an archaeologist at the University of California,
Santa Cruz, said the new findings were very exciting because they showed the
speed with which a genetic mutation can be favored under conditions of strong
natural selection, demonstrating the possible rate of evolutionary change in
humans.
The genetic data fitted in well, she said, with archaeological and linguistic
evidence about the spread of pastoralism in Africa. The first clear evidence
of cattle in Africa is from a site 8,000 years old in northwestern Sudan.
Cattle there were domesticated independently from two other domestications, in
the Near East and the Indus Valley of India.
Nilo-Saharan speakers in Sudan and their Cushitic-speaking neighbors in the
Red Sea hills probably domesticated cattle at the same time, because each has
an independent vocabulary for cattle items, said Dr. Christopher Ehret, an
expert on African languages and history at the University of California, Los
Angeles. Descendants of each group moved south and would have met again in
Kenya, Dr. Ehret said.
Dr. Tishkoff detected lactose tolerance among Cushitic speakers and
Nilo-Saharan groups in Kenya. Cushitic is a branch of Afro-Asiatic, the
language family that includes Arabic, Hebrew and ancient Egyptian.
Dr. Jonathan Pritchard, a statistical geneticist at the University of Chicago
and a co-author of the new article, said there were many signals of natural
selection in the human genome but it was usually hard to know what was being
selected for. In this case Dr. Tishkoff clearly defined the driving force, he
said.
The mutations Dr. Tishkoff detected are not in the lactase gene itself but a
nearby region of the DNA that controls the activation of the gene. The finding
that different ethnic groups in East Africa have different mutations is one
instance of their varied evolutionary history and their exposure to many
different selective pressures, Dr. Tishkoff said.
There is a lot of genetic variation between groups in Africa, reflecting the
different environments in which they live, from deserts to tropics, and their
exposure to very different selective forces, she said.
People in different regions of the world have evolved independently since
dispersing from the ancestral human population in northeast Africa 50,000
years ago, a process that has led to the emergence of different races. But
much of this differentiation at the level of DNA may have led to the same
physical result.
As Dr. Tishkoff has found in the case of lactose tolerance, evolution may use
the different mutations available to it in each population to reach the same
goal when each is subjected to the same selective pressure. I think its
reasonable to assume this will be a more general paradigm, Dr. Pritchard said.
==
There are hundreds of scientific research articles about evolution published
each and every year. Here's a selection of professional science journals (in
the U.S. and the U.K.) that routinely or exclusively publish professional
scientific research concerning evolution:

PLoS Biology
(published by the Public Library of Science)
http://biology. plosjournals. org/

PLoS Genetics
(published by the Public Library of Science)
http://genetics. plosjournals. org/

Science
(published by the American Association for the Advancement of Science)
http://www.sciencem ag.org/

Nature
http://www.nature. com/

Journal of Biology
(published by BioMed Central)
http://jbiol. com/

Journal of Evolutionary Biology
http://www.blackwel lpublishing. com/journal. asp?ref=1010- 061X
view online content:
http://www.blackwel l-synergy. com/rd.asp? code=JEB& goto=journal

International Journal of Organic Evolution
http://evol. allenpress. com/evolonline/ ?request= index-html# Evolution_
Journal
[link may be line-wrapped]

Molecular Biology and Evolution
(published by the Society for Molecular Biology and Evolution)
http://www.mbe. oupjournals. org

Evolution & Development
http://www.blackwel lpublishing. com/journal. asp?ref=1520- 541X

Trends in Ecology & Evolution
http://www.elsevier .com/wps/ find/journaldesc ription.cws_ home/30339/
description
[link may be line-wrapped]

Trends in Genetics
http://www.elsevier .com/wps/ find/journaldesc ription.cws_ home/405918/
description
[link may be line-wrapped]

Integrative and Comparative Biology
(Journal of the Society for Integrative and Comparative Biology; published as
the American Zoologist from 1961 to 2001)
http://www.sicb. org/az/

Invertebrate Biology
(Journal of the American Microscopical Society)
http://www.inverteb ratebiology. org/

Proceedings of the National Academy of Sciences (PNAS)
Biological Sciences
http://www.pnas. org/current. shtml#BIOLOGICAL _SCIENCES

Palobiology
Journal of Paleontology
(both published by The Paleontological Society)
http://www.psjourna ls.org/paleoonli ne/?request= get-archive

The Journal of Vertebrate Paleontology
(published by the Society of Vertebrate Paleontology)
http://www.vertpale o.org/jvp/

Paleontologia Electronica
http://palaeo- electronica. org/

Cladistics
The International Journal of the Willi Hennig Society
http://www.blackwel lpublishing. com/journal. asp?ref=0748- 3007

Evolution
International Journal of Organic Evolution
http://evol. allenpress. com/evolonline/ ?request= get-archive

Biological Journal of the Linnean Society
http://www.blackwel lpublishing. com/journal. asp?ref=0024- 4066

Zoological Journal of the Linnean Society
http://www.blackwel lpublishing. com/journal. asp?ref=0024- 4082

Botanical Journal of the Linnean Society
http://www.blackwel lpublishing. com/journal. asp?ref=0024- 4074

Evolutionary Ecology
(published in the Netherlands)
http://www.springer .com/west/ home/life+ sci?SGWID= 4-10027-70- 35681186- 0
[link may be line-wrapped]

Genetics
http://www.genetics .org/

Molecular Phylogenetics and Evolution
http://www.elsevier .com/wps/ find/journaldesc ription.cws_ home/622921/
description
[link may be line-wrapped]

Proceedings of the Royal Society: Biological Sciences
http://www.pubs. royalsoc. ac.uk/index. cfm?page= 1087

Journal of Zoological Systematics and Evolutionary Research
http://www.blackwel lpublishing. com/journal. asp?ref=0947- 5745

Evolutionary Bioinformatics Online
http://www.la- press.com/ evolbio.htm
===
Public acceptance of evolution
Human beings, as we know them, developed from earlier species of animals: true
or false? This simple question is splitting America apart, with a growing
proportion thinking that we did not descend from an ancestral ape. A survey of
32 European countries, the US and Japan has revealed that only Turkey is less
willing than the US to accept evolution as fact.
Religious fundamentalism, bitter partisan politics and poor science education
have all contributed to this denial of evolution in the US, says Jon Miller of
Michigan State University in East Lansing, who conducted the survey with his
colleagues. "The US is the only country in which [the teaching of evolution]
has been politicised," he says. "Republicans have clearly adopted this as one
of their wedge issues. In most of the world, this is a non-issue."
Miller's report makes for grim reading for adherents of evolutionary theory.
Even though the average American has more years of education than when Miller
began his surveys 20 years ago, the percentage of people in the country who
accept the idea of evolution has declined from 45 in 1985 to 40 in 2005
(Science, vol 313, p 765). That's despite a series of widely publicised
advances in genetics, including genetic sequencing, which shows strong overlap
of the human genome with those of chimpanzees and mice. "We don't seem to be
going in the right direction," Miller says.
There is some cause for hope. Team member Eugenie Scott of the National Center
for Science Education in Oakland, California, finds solace in the finding that
the percentage of adults overtly rejecting evolution has dropped from 48 to 39
in the same time. Meanwhile the fraction of Americans unsure about evolution
has soared, from 7 per cent in 1985 to 21 per cent last year. "That is a group
of people that can be reached," says Scott.
The main opposition to evolution comes from fundamentalist Christians, who are
much more abundant in the US than in Europe. While Catholics, European
Protestants and so-called mainstream US Protestants consider the biblical
account of creation as a metaphor, fundamentalists take the Bible literally,
leading them to believe that the Earth and humans were created only 6000 years
ago.
Ironically, the separation of church and state laid down in the US
constitution contributes to the tension. In Catholic schools, both evolution
and the strict biblical version of human beginnings can be taught. A court ban
on teaching creationism in public schools, however, means pupils can only be
taught evolution, which angers fundamentalists, and triggers local battles
over evolution.
These battles can take place because the US lacks a national curriculum of the
sort common in European countries. However, the Bush administration's No Child
Left Behind act is instituting standards for science teaching, and the battles
of what they should be has now spread to the state level.
Miller thinks more genetics should be on the syllabus to reinforce the idea of
evolution. American adults may be harder to reach: nearly two-thirds don't
agree that more than half of human genes are common to chimpanzees. How would
these people respond when told that humans and chimps share 99 per cent of
their genes?
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Paleontologists Find Species With Links to 'Lucy Skeleton'
In following the fossil tracks of human evolution, scientists have for years
searched for links between Australopithecus, the kin of the famous "Lucy"
skeleton, and even earlier possible ancestors. Now, they think they have found
some connections in Ethiopia.
An international team of paleontologists is reporting the discovery of
transitional species superimposed in sediments in the neighborhood of a single
site.
Tim D. White, a paleontologist at the University of California, Berkeley, who
was a leader of the team, and his colleagues said the 4.1-million-year-old
fossils were anatomically intermediate between the earlier species
Ardipithecus ramidus and the later species Australopithecus afarensis, the
Lucy family. The newfound bones and teeth are the earliest remains of the most
primitive Australopithecus, known as anamensis.
"This new discovery closes the gap between the fully blown australopithecines
and earlier forms we call Ardipithecus," Dr. White said in a statement. "We
now know where Australopithecus came from before four million years ago."
The scientists said the fossils supported the hypothesis that Australopithecus
anamensis was a direct ancestor of afarensis, which lived between 3.6 million
and 3 million years ago. The Australopithecus genus  resembling apes in
stature and small brain but unlike the great apes in that it walked on two
legs  is thought to have given rise to our own genus, Homo.
Some later australopithecines survived until about 1.2 million years ago,
existing in Africa as contemporaries with Homo erectus, a predecessor of
modern humans.
The genus Ardipithecus, discovered by Dr. White in 1992, appears to have lived
between 5.7 million and 4.4 million years ago. It was even more apelike, but
also walked on two legs.
The relationship between Ardipithecus and Australopithecus, scientists said,
remains unclear because of the wide gap in their chronology. Still, they
suggested that one probably led to another.
Dr. White said in a telephone interview that a key to interpreting the new
anamensis was where it was discovered, in the Middle Awash valley of the Afar
Region of Ethiopia. The area, about 140 miles northeast of Addis Ababa,
Ethiopia's capital, has also yielded critical evidence of afarensis and the
ramidus species of Ardipithecus.
"Finding these three things in time sequence in a single place, that's never
happened before," Dr. White said.
In the journal report, the scientists said the evidence suggested "a
relatively rapid shift from Ardipithecus to Australopithecus in this region of
Africa."
The new anamensis fossils were uncovered first at Aramis and then at a place
called Asa Issie. The teeth and jawbones of eight individuals were found at
Asa Issie, the most recent of the discoveries coming last December. The
fieldwork and analysis was conducted by scientists from Ethiopia, Japan,
France and the United States, with support from the National Science
Foundation.
Giday WoldeGabriel, a geologist at the Los Alamos National Laboratory and
another leader of the team, said the abundance of monkey and other mammal
bones and petrified wood found at the sites showed that this was a woodland
ecology between four million and six million years ago.
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Early Land Animals Could Walk And Run Like Mammals, Ne