Saturday, May 31, 2008

Creationism is Doomed

I have come to realize that creationists' philosophy is fundamentally very inconsistent in a way that I had not before thought of. Take a look at the Answers in Genesis Statement of Faith. It says:

"No apparent, perceived, or claimed interpretation of evidence in any field, including history and chronology, can be valid if it contradicts the Scriptural record. "

Notice that they said "interpretation of evidence" rather than just "evidence". In science, things can often be explained in a number of different ways. Creating an explanation is what scientists call "formulating a hypothesis". The plan is that, from there, we try to test each explanation to prove it wrong. If an explanation is ever at odds with direct observation, the explanation is thrown out. Once a hypothesis is the last one standing, after passing a number of tests, it is considered true until it is proven false or a better explanation comes along.

Creationists, however, want to side step this. They are making their assertion immune to any tests. Radiometric dating doesn't prove the earth is old, radiometric dating is wrong. Tree ring dating doesn't prove the earth old, tree ring dating is wrong. The fossil record appears to show a progression of life? The flood sorted the fossils so that there appears to be a 'progression'. Amphibians just so happened to make their first appearance in the fossil record after fish but before reptiles.

They will, of course, insist that evolutionists do the same thing by assuming Origin of Species is true as much as they assume the Bible is true. But this defense is blatantly false, as evolutionary theory is open to revision. Darwin's original idea has been amended many times, and all on the basis of new evidence. Darwin once speculated that bears had evolved into whales. This speculation was discarded once it was discovered through biochemistry that bears were so dissimilar to whales that they could not be closely related. The fossil record provided evidence that the ancestors of whales were more like wolves than bears (Look up "Pakicetus" or "Ambulocetus").

Creationism is doomed because it wants to play in the realm of science, but will not allow scientific evidence to enter into the debate about whether their beliefs are correct or not.

Wednesday, May 28, 2008

Evolution in the South, Pt. 2

Yesterday I revealed that when I went to public school, evolution was not taught. Allow me to back pedal and tell a story of my education beforehand: I was homeschooled until tenth grade, and my Mother purchased Christian Biology books for me to use. No doubt her intentions were good. The Biology books I used always taught against evolution, and did so in a way that anyone familiar with creationist propaganda will recognize. I took a look at the books, which my Mom still has, and they say all of the following: Neanderthals were just people with rickets, Man's closest living relative is the bullfrog, Evolution breaks the Second Law of Thermodynamics, and so on and so on. There are more errors in those books' discussion of evolution than I could possibly document.

One particularly interesting feature of this book (Published by A Beka) is that it states vestigial organs, such as the appendix and tailbone, all serve a purpose and are therefore not evidence of evolution. Later on, it states that the "vestiges of legs and a pelvis" found in snakes are evidence that they are descended from legged creatures, as implied by Genesis (In Gen. 3:14 God curses the snake to crawl on its belly, implying it previously walked). If vestigial organs may serve a purpose, be it a lesser one, and are still evidence of a creature's ancestry, then why don't these folks take the tailbone, intristic ear muscles, goosebumps, etc. as evidence of our descent from other animals?

Tuesday, May 27, 2008

Evolution in the South

Hi Everyone, I wanted to make a personal post today. As you may know, I am a Southerner, born and raised in Alabama. The South is making progress toward accepting evolution, but we have a way to go. I went to the Georgia Aquarium in Atlanta, and was surprised to hear this comment from one of the speakers talk about the Whale Shark: He said that he would like to tell us why the whale shark isn't really closely related to the whale, but he gets in trouble every time he says the 'E' word. It is ashame that speakers cannot feel free to tell children about the most fascinating fact of Biology. While we were at the aquarium, I pointed out to my younger sister that whales move their bodies vertically to swim, and so do otters. I told her that it was because they were related: Whales come from land mammals, so they swim like land mammals. Her face lit up, and I could tell it made sense to her. Later on, I was reading "Origin of Species" in the hotel we were at, and my sister asked, "That's by Charles Darwin, Isn't It?" I told her it was, and she responded, "Oh yeah, we learned all about him and the Galapagos Finches in school." I may have told this story before, but when I was in school (PUBLIC School, mind you) I wasn't taught evolution (In a Botany and Zoology class, no less) but that I should be careful when I get into college not to let my professors sway my faith. Outrageous, isn't it? I am glad that my siblings will get a better education, and that the other small town children are being exposed to a view different from the creationist propaganda.

Thursday, May 22, 2008

Frog-Amander Transitional Fossil Found

Found via Livescience.

A frog-like creature with a stubby tail once paddled through a quiet pond in what is now Texas, snapping up mayflies while keeping an ear out for bellowing mates, new fossil evidence suggests.
That was about 290 million years ago.

In 1995, the amphibian specimen was discovered in fish quarry sediments in Baylor County, Texas, though it wasn't until recently that paleontologists inspected and described the new species. Called Gerobatrachus hottoni after its discoverer Nicholas Hotton, a paleontologist at the Smithsonian Institution, the creature represents a transitional amphibian, sporting features of both frogs and salamanders.

"This amphibian is from near to the point where frogs and salamanders first split," said lead researcher Jason Anderson, a vertebrate paleontologist at the University of Calgary in Canada. "This is kind of an early frog-amander."

The finding, detailed in this week's issue of the journal Nature, supports the idea that frogs and salamanders evolved from one ancient amphibian group called temnospondyls.

Like modern salamanders, the fossil of Gerobatrachus has two fused bones in its ankle. And like modern frogs, the frog-amander sports a large ear drum, or tympanic ear, which Anderson said the ancient amphibian likely used for hearing calls from mates.

Wednesday, May 21, 2008

A "Just So" Story About Cultural Evolution

Lately a lot of people have been questioning why humans didn't get together sooner and start a civilization. I have countered this by asking why African tribes haven't independently invented a microwave. I think both of these questions, when seriously pondered, reveal their own answer.

My hypothesis is this:

Imagine thousands of human tribes scattered all over the earth. Each speaks a different language and keeps to itself. Now imagine one "tribe" which can communicate easily within itself, with all people intermingling and exchanging information. Which one is better?

The latter. Think about someone like Thomas Edison, Galileo, or Stephen Hawking. The entire Universal "tribe" benefits from those very, very rare geniuses who come along and share their insight with the rest of us. Instead of a single, small tribe gaining their insight (and possibly losing it or not recognizing its worth!), everyone can benefit. We benefit from countless intellectuals who would belong to another "tribe" if we were more divided.This brings me to the origins of civilization: What happened to us, when we were living in small tribes that made us settle down and begin agriculture? I suggest that primitive tribes had to "wait" - for lack of a better word- for someone who thought indepently enough, could organize others well enough, and was viewed as powerful enough within the tribe to persuade others to settle down for a life of agriculture. Even then there were no guarantees: Several of these proto-farming tribes may have started up and gone extinct before one managed to stay around.

Once the right one managed to survive and handle itself, the intellectual abilities of the tribe grew by leaps and bounds. The population grew, and every generation or two someone would be born who could teach the tribe something; a slightly more complex form of language or a new farming technique, for instance.

This affect is what is responsible for the dramatic boom in technology and science we have seen over the past few hundred years. Two British scientists discovered the key to life, DNA, and shared it with Americans, Russians, Germans, and etc. Thomas Edison invented the lightbulb, among other ingenius inventions, and shared this information with the rest of the world.

That's my hypothesis.

Monday, May 19, 2008

The Intellectual Poverty of Pop Science

Something needs to be done. You see, most creationists, most people, in fact, do not have the attention span to watch Carl Sagan's Cosmos, read The Selfish Gene, Why Darwin Matters, or Finding Darwin's God. Yet they do have the attention span to flip through Scientific American on occasion, watch the news, or read any other pop science magazine. The problem with the pop science tabloids-er, I mean magazines- Is that they oversimplify and love to use "buzz words". For instance, I have seen, on at least one occasion, a magazine describe evolution as "long periods of time + chance". This is a gross oversimplification. Anyone who understands evolution knows that while variation might be random, the variations which become common are not. In any population with some genetic variety, evolution is simply bound to take place. Natural Selection is not random.

Even worse is when science news sites have decided to label the platypus as some wild and crazy crossbreed of birds, reptiles, and mammals. PZ Myers has taken the time to fully correct this mistaken position and explain the way it really is. Blogger Chimera Contemplations has even written us a poem about this incident, allow me to quote a few lines:

A chimera is a mythical creature
With breathing fire as a prominent feature
Part lion, part serpent, part goat but all Greek
Bellerophon and Pegasus killed this freak

In conclusion: Does it reflect poorly on creationist for only obtaining a superficial understanding of science through pop literature, or does it reflect even worse on the folks who will dumb down science to the point of distortion just so that a few extra idiots will buy it?

Sunday, May 18, 2008

The Evolution of Bats

Stephen Matheson recently wrote a very interesting article on the evolution of bats. It examines the genetic changes which led to the bats gradual transition from tree climbing mammals to night wings.

I do have one thing I'd like to add to the article: It states that "The fossils can't yet show us how paws gave rise to wings". This is true, there is not a sequence of fossils that show this transition (Bats are too fragile to fossilize well). However, there was a fossil reported a few months ago which definitely represented a transitional stage between tree climbers and bats.

Stephen Jay Gould Interview

Youtube has a six part interview with Dr. Stephen Jay Gould:

Part 1

This is a good video to reference when creationists rag on the peppered moth story, as this actually filmed peppered moths on a tree trunk being eaten by birds!!

Saturday, May 17, 2008

Ancient Bird is 'Missing Link' To Archaeopteryx

Found @ New Scientist

Avian evolution made important advances between Archaeopteryx and the Yixian birds. "Archaeopteryx was an efficient powered flapping flyer, but lacked many of the adaptations of the skeleton seen in modern birds – especially fusions of bones that support flight muscle and reduce length of the tail," Benton told New Scientist.

Confuciusornis was a strong flyer, with flight muscles anchored on the wing by a large ridge of bone known as the deltopectoral crest, and on the body by a large fused sternum.

With a pair of separate sternal plates and a smaller deltopectoral crest, Eoconfuciusornis is more advanced than Archaeopteryx, and the most primitive, as well as the earliest, member of the Confuciusornis family.

Friday, May 16, 2008

Holocaust Denial and Evolution Denial

I stumbled across a blog debunking evolution denial and look what I found:

"A classic denial strategy is to take a quote from a historian and pretend that the historian is saying what the denier wants him to say. It's a subtle form of lying that we define as quote-mining."

Sounds familiar.

Now take a look at this article:

"Those who argue that the holocaust deniers must be given a fair hearing fail to recognize that the deniers' quest is not a search for truth. Rather they are motivated by racism, extremism, and virulent anti-Semitism."

In other words, deniers demand "equal time" for their views, and their views are based on idealogy (not science). Deja Vu. The article goes on:

"Those who are committed to the liberal idea of dialogue fail to recognize that certain views are beyond the bounds of rational discourse. After all, these views do not emanate from rational or honest inquiry. Thomas Jefferson argued that in a setting committed to the honest pursuit of truth, all ideas and opinions must be tolerated. But he added a caveat, which is particularly applicable: "We are not afraid to follow truth wherever it may lead, nor to tolerate any error so long as reason is left free to combat it" (emphasis added). In the case of Holocaust denial, reason becomes hostage to particularly odious ideology. "

So, why don't we give up on fighting the claims of creationists, and focus in on the idealogy? How should we go about this? Leave a comment and let me know what you think.

Thursday, May 15, 2008


This is a really, really hilarious cartoon.

And by the way, please sign up for email updates (over to your right >>).

Wednesday, May 14, 2008

Transitional Fossils: More by the Second

A fossil which was hailed Friday, May 9, as the missing link in a worldwide evolutionary mystery has been discovered by a rock hunter poking around after a building demolition in Germany.

The carpoid, which lived 360 million years ago, is an ancestor of today's sea urchins and starfish. It closes a 70-million-year gap in the evolutionary record of a group of creatures known as the echinoderms which live on the sea bottom and have protective spikes.

Some evolutionary theorists have suggested that vertebrate creatures including mankind are cousins of the echinoderms.

Until its discovery in Wuppertal, Germany, no carpoid had been known between 390 million and 320 million years ago, geologist Hans Martin Weber of the Rhineland local authority said in Cologne on Friday.

The amateur palaeontologist found several fragments up to 1.2 centimetres in size of the creature's shell and fore end in some rock exposed after a kindergarten had been ripped down. He took them to Weber to identify.

Geologist Weber said the rock had once been silt at the bottom of a tropical sea.
Other fossils found in the rock were the first of their types in Germany. Weber said the site had been well known to fossil hunters for 100 years and it was amazing no one had seen the echinoderm before.

Tuesday, May 13, 2008

Praying Mantis Missing Link

Found Via National Geographic:

A praying mantis trapped in amber that was found in Japan in January 2008 dates back 87 million years, to the late Cretaceous period.

Researchers say the mantis, one of only seven in the world from this geologic period, displays unique features that may mean it is a "missing link" between the ancient insects and their modern counterparts.

"Modern mantises have a series of spines—maybe five or six—on their forelegs, to help them catch prey," Ueda said.

"The American Museum of Natural History has told us that no mantis from the Cretaceous period has ever been found with spines"—but the new specimen has two such spines protruding from its femur.

Monday, May 12, 2008

This I believe

The Best "This I Believe" Essay I have ever read:
I Am Evolution

Sunday, May 11, 2008



The site is mainly going to be an archive of my best writings, although I did manage to type up a few new things especially for the site. If you have a blog, please link to me by hyperlinking the words "Answers in Genesis". This will help my site come up when people search for AiG. If you do not have a blog, please digg or stumble the site, announce the site on a forum, tell other people, etcetera. I know there are enough people reading this blog that the word will get out if everyone does something. Do it for the people who are buying into their propaganda without giving it further thought. Do it to expose Ken Ham and his gang for the sorry liars they are. Do it to improve people's knowledge of evolution and creationism. Just do it.

Friday, May 9, 2008

Ken Miller Trashes 'Expelled'

I just read Ken Miller's review of Expelled. I am going to quote some of the review and let it speak for itself:

Despite these falsehoods, by far the film's most outlandish misrepresentation is its linkage of Darwin with the Holocaust. A concentration camp tour guide tells Stein that the Nazis were practicing "Darwinism," and that's that. Never mind those belt buckles proclaiming Gott mit uns (God is with us), the toxic anti-Semitism of Martin Luther, the ghettoes and murderous pogroms in Christian Europe centuries before Darwin's birth. No matter. It's all the fault of evolution.

Why is all this nonsense a threat to science? The reason is Stein's libelous conclusion that science is simply evil. In an April 21 interview on the Trinity Broadcast Network, Stein called the Nazi murder of children "horrifying beyond words." Indeed. But what led to such horrors? Stein explained: "that's where science in my opinion, this is just an opinion, that's where science leads you. Love of God and compassion and empathy leads you to a very glorious place. Science leads you to killing people."

According to Stein, science leads you to "killing people." Not to cures and vaccines, not to a deeper understanding of nature, not to wonders like computers and cellphones, and certainly not to a better life. Nope. Science is murder.

"Expelled" is a shoddy piece of propaganda that props up the failures of Intelligent Design by playing the victim card. It deceives its audiences, slanders the scientific community, and contributes mightily to a climate of hostility to science itself. Stein is doing nothing less than helping turn a generation of American youth away from science. If we actually come to believe that science leads to murder, then we deserve to lose world leadership in science. In that sense, the word "expelled" may have a different and more tragic connotation for our country than Stein intended.


What can we do to change this situation?

Thursday, May 8, 2008

Evolution of the Eye

NCSE has a youtube profile and is postig all kinds of cool videos, like this one:

Wednesday, May 7, 2008

Expelled Exposed

Good News! My entry to the "Expelled" Contest was published on ExpelledExposed.Com

Check out the entry under 'Nicholas Covington':

"Darwin was never able to point to any clear evidence of any species that had originated by evolution. And there hasn’t been much progress in Darwinism since then." --Ben Stein

Nicholas Covington answers
Scientists have now directly observed new species evolving ( Recently a scientist performed experiments which show that new species of stick insect originate from small adaptations to their environment via natural selection ( Scientists have also studied a new species of mosquito which evolved in the underground tunnels of London ( Obviously there has been a lot of progress made in the field of evolutionary biology.

Sunday, May 4, 2008

You Know You're A Creationist If... Part II

Anyone remember my last post on "You Know You're a Creationist"? Please submit any ideas you have, I intend to build on this.

You know you're a creationist if...

...You call evolution a dogma, and then complain that scientists are always changing their story.

...You think evolution is a big conspiracy that no one can dissent from, yet you point to scientists' disagreements to show how unstable evolutionary theory is.

...You claim that similarity isn't evidence of common descent, but never second guess a DNA paternity test.

Friday, May 2, 2008

Evolution: The Fossils say Yes!

The fossils say yes: the discovery of transitional forms has filled in some of the most talked-about gaps in the fossil record

Natural History, Nov, 2005 by Donald R. Prothero

It has been asserted over and over again, by writers who believe in the immutability of species, that geology yields no linking forms. This assertion ... is certainly erroneous.... What geological research has not revealed, is the former existence of infinitely numerous gradations ... connecting together nearly all existing and extinct species.
--Charles Darwin, the Origin of Species

When Darwin first proposed the idea of evolution by natural selection in 1859, the fossil record offered little support for his ideas. Darwin even devoted two entire chapters of the Origin of Species to the imperfection of the geologic record, because he was well aware it was one of the weakest links in his arguments. Then, just two years after his book was published, the first specimen of Archaeopteryx was discovered, hailed by many as the "missing link" between birds and reptiles. By the late nineteenth century, fossils helped demonstrate how the modern thoroughbred horse evolved from a dog-size, three-toed creature with low-crowned teeth. (The understanding of those fossils has since been much refined.)
Fossil evidence supporting evolution has continued to mount, particularly in the past few decades. DNA analysis, moreover, has helped make sense of how the evidence fits together in the family tree of life on Earth. Unfortunately, many people still think, quite erroneously, that the fossil record shows no "transitional forms." In large part, that misconception is the product of the campaign of misinformation--or disinformation--spread by the creationist movement.
The fossil record is far from perfect, of course. By most estimates, less than 1 percent of all the species that have ever lived are preserved as fossils. The reason for the scarcity is simply that the physical conditions needed to turn a dead organism into a fossil lasting millions of years are unusual.
Nevertheless, there are numerous excellent specimens that reflect transitional stages between major groups of organisms. Many more fossils exhibit how "infinitely numerous gradations" connect the species. The one caveat is that when a sequence of fossils appears to follow a direct line of descent, the chances are slim that they actually bear such precise interrelations. Paleontologists recognize that when one fossil looks ancestral to another, the first fossil is more safely described as being closely related to the actual ancestor.
The classic story of the evolution of the horse is a good example. The various known fossils were once arranged--simplistically, it turns out--into a single lineage leading from "Eohippus" to Equus. When more fossils became available, paleontologists revised that simple lineage. The fossils now give a branching and very bushy picture of equine evolution, with numerous now-extinct lineages living side by side. One quarry in Nebraska has yielded a dozen distinct species of fossil horses, in rock about 12 million years old. The earliest horses, such as Protorohippus (from early in the Eocene epoch, about 53 million years ago), are virtually indistinguishable from Homogalax, the earliest member of the lineage, which also gave rise to tapirs and rhinoceroses. Very early in my career, when I was taking an undergraduate paleontology class, I discovered just how tough it is to sort out those two ancient genera.
Perhaps the most remarkable recent discoveries are the numerous fossils that connect whales with their four-legged terrestrial ancestors. If you look at dolphins, orcas, and blue whales, all fully aquatic animals, you would have a hard time imagining them walking on land. Yet even living whales retain vestiges of their hips and thighbones, deeply buried in the muscles along their spines. Paleontologists have known for a long time, on the basis of detailed features of the skull and teeth, that whales are closely related to hoofed mammals. But creationists long touted the absence of transitional fossils for whales as evidence against evolution.
The balance has now changed. In 1983 specimens of Pakicetus were discovered Pakistan in early Eocene beds about 52 million years old. Although the body of Pakicetus was primarily terrestrial, it had the skull and teeth of the ancient archaeocetes, the earliest family of whales--which swam the world's oceans in the Middle Eocene epoch, about 50 million years ago.
Then, in 1994, Ambulocetus natans (literally, the "walking whale that swims") was discovered, also in Pakistan [see illustration below]. The animal was the size of a large sea lion, with broad webbed feet on both fore--and hind limbs, so it could both walk and swim. Yet it still had tiny hooves on its toes and the primitive skull and teeth of the archaeocete. Ambulocetus apparently swam much like an otter, with an up-and-down motion of the spine, the precursor to the motion of the flukes of a whale's tail. In 1995 yet a third transitional creature was discovered, Dalanistes, with shorter legs than Ambulocetus, webbed feet, a longer tail, and a much larger and more whalelike skull.
Today more than a dozen transitional whale fossils have been unearthed--an excellent series for such rarely fossilized animals. DNA from the living species suggests that whales are descended from even-toed hoofed mammals known as artiodactyls and, in particular, are most closely related to the hippopotamus. That hypothesis was dramatically confirmed by the discoveries in 2001 of the "double-pulley" anklebone, which is characteristic of artiodactyls, in two kinds of primitive whales.
Whales are not the only aquatic mammals with terrestrial ancestors. Modern sirenians (manatees and dugongs) are large, docile, aquatic herbivores that have flippers for forelimbs and no hind limbs. In 2001 Daryl Domning, a marine mammal paleontologist at Howard University in Washington, D.C., described a remarkably complete skeleton of Pezosiren portelli from Jamaican deposits about 50 million years old. That animal had the typical skull and teeth of a sirenian, and even the thick sirenian ribs made of dense bone, which serve as ballast. Yet it had four legs as well, all with feet, not flippers. Strong transitional fossils also link seals and sea lions to bearlike ancestors.
The origin of mammals is well documented. Mammals and their extinct relatives belong to a larger group known as the Synapsida. The earliest members of the group were once known as "mammal-like reptiles," even though they were not true reptiles but had already evolved to become a separate branch of animals. Among them was Dimetrodon, the largest predator on Earth about 280 million years ago. (Its sail-shaped back is familiar from toy-dinosaur kits for children, even though it was not a true dinosaur.) Although it was a primitive form, Dimetrodon had large, stabbing canine teeth and some of the specialized skull features of mammals.
For the next 80 million years, synapsids evolved into various wolflike and bearlike predators, as well as into an array of peculiar piglike herbivores. Along the way, they acquired progressively more mammalian features: additional jaw muscles that enabled complex chewing motions; a secondary palate covering the old reptilian palate and nasal region, which enabled them to breathe and eat at the same time; multicusped molars for chewing rather than gulping their food; enlarged brains; relatively upright (rather than sprawling) posture; and a muscular diaphragm in the rib cage for efficient breathing. There are even signs that they had hair, a quintessentially mammalian feature. The story of the synapsids culminates in the appearance of the earliest true mammals--shrew-size creatures--in fossil beds about 200 million years old in China, South Africa, and Texas.
Among the most remarkable transformations that took place as the mammals emerged are the ones that can be observed in fossils of the lower jaws. In reptiles and primitive synapsids, the right and left lower jaws are each made up of a number of bones, one of which is the dentary, or tooth-bearing, bone. As synapsids evolved, the dentary bone grew progressively larger until it took over the role of hinging the jaw to the skull. One of the other reptilian jawbones shrank until it vanished, whereas the other two shifted to the middle ear. There they became the anvil and the hammer, minute bones that transmit sound from the eardrum to the stirrup bone and, ultimately, to the inner ear. The shift in function seems bizarre until you realize that in reptiles, sound vibrations from the lower jaw travel through the skull bones to the inner ear, and that, along with the vibrations that travel from the eardrum, those vibrations are important sources of sensation.
Excellent "missing links" now exist for other major groups as well. Many fossil species show the transition from dinosaurs to birds. Archaeopteryx, for instance, discovered in Europe in Late Jurassic fossil beds about 150 million years old, had teeth. Slightly younger fossils, from the Chinese Lower Cretaceous, about 140 million years ago, had more birdlike features. Sinornis, for instance, had wings it could fold against its body, grasping feet with an opposable toe, and tailbones fused into a single element. Confuciusornis sported the first toothless beak. Lower Cretaceous rocks in Spain, about 130 million years old, have yielded Iberomesornis, which had a large, keeled breastbone to which powerful flight muscles were anchored. Still, the creature had the primitive long backbone of a dinosaur.
Such bird fossils are now joined in the web of ancient life-forms by numerous, recently discovered fossils of nonflying, nonavian dinosaurs, closely related to Velociraptor of Jurassic Park fame. Those fossils, such as Microraptor and Caudipteryx, had well-developed feathers, suggesting that feathers originally served other functions, such as insulation, long before they became useful for flight [see "Bird's-eye View," by Matthew T. Carrano and Patrick M. O'Connor, May 2005].
Another transition that is now well documented is the conquest of the land by the amphibians. For decades the only good intermediate fossil between fishes and amphibians was Ichthyostega, from the Late Devonian epoch (about 360 million years ago) of Greenland and Spitzbergen. Although Ichthyostega resembled many amphibians in having well-developed legs, a complete shoulder girdle, and hips fused to the backbone, it still had fishlike gill slits, a sensory system on its face for detecting underwater currents, and a long, fishlike tail fin.
More recent discoveries, such as Acanthostega from the same beds, show that the picture is much more complicated and interesting [see illustration at left]. Acanthostega had ear bones that were still adapted for underwater hearing, a longer tail fin than Ichthyostega, and better-developed gills, making it more primitive and aquatic than Ichthyostega. Acanthostega also had as many as eight toes on each of its four feet--rather than five, which became the standard in most early four-footed creatures. Apparently, its limbs were primarily adapted for swimming and walking along the bottom of a lake, rather than for crawling on land. Contrary to the popular stoW that four legs evolved because they enabled animals to crawl out onto the land (to escape drying ponds, chase new food sources, and so forth), it now appears that legs evolved for walking underwater (as most salamanders still do today). They became secondarily useful on land, because they were already in place.
What about the transitional forms that led to our favorite species, Homo sapiens? Not long ago, the fossil record of the human family was severely limited, and readily thrown into confusion by a single fraudulent "fossil" such as the 1912 hoax known as Piltdown Man. But in the past three decades new findings have exploded. In Chad, fossils of Sahelanthropus were discovered in beds between 6 million and 7 million years old. In Ethiopia, the new genus Ardipithecus and two new species of Australopithecus (A. anamensis and A. bahrelghazali) were unearthed in beds between 2 million and 5 million years old. Several species of our own genus, Homo, which goes back at least 2 million years, have now been identified.
In short, the human fossil record has become quite dense and complete, and the newfound samples have led to some surprises. For example, contrary to the expectations of earlier anthropologists, the fossils show that bipedalism arose before enlarged brains, which came quite late in human evolution.
The origin of vertebrates as a whole once also presented a frustrating gap in the fossil record. Biologists could examine the many living animals (such as lancelets and sea squirts) that represented stages in the transition from the invertebrates to the earliest jawless fishes. Until recently, however, few good fossils had been identified from beds older than about 480 million years, near the beginning of the Ordovician period. What's more, they were only scattered bony scales and plates.
But recent discoveries in China from the Middle Cambrian epoch, between 510 million and 500 million years ago, have included not only the earliest relatives of the lancelets, but also some soft-bodied specimens that appear to be the earliest vertebrates. Thus, backboned animals can now be traced al] the way back to the Cambrian, when most of the modern branches of animals originated.
As the 150th anniversary of Darwin's Origin approaches, the fossil evidence now available would make Darwin proud, rather than apologetic. Evolutionary biologists can also look forward to many more discoveries. Some will come as a surprise, like the early small-brained bipedal hominids. Some will force paleontologists to revise their ideas about evolutionary events. But the fossil record is no longer the embarrassment that it was in Darwin's day.
COPYRIGHT 2005 Natural History Magazine, Inc.COPYRIGHT 2005 Gale Group