Darwin Day & the Fossil Evidence for Evolution

Wow.

Last night's Darwin Day event was a resounding success! We easily had at least fifty people -- FIFTY -- in attendance.

Of course, the space I'd reserved really should only have accommodated no more than about 30. So space was tight, and due to the unusual floor-plan, some people were left crowded in the anteroom standing-room-only style. Sorry about that! I'll need to find a larger space for any future guest speakers if the turnout to this is any indication. But we're all friends now, so no worries about getting a little cozy, right?

Alan Rogers, our guest speaker, was originally going to present on the "Evolution of the Debate Over Evolution." But his presentation evolved (sorry), and he instead gave a talk entitled "Does Evolution Make Big Changes."

For those that are interested, a PDF of the presentation slides is available here.

It's interesting that Dr. Rogers chose the subject of fossil evolution, as I was working yesterday on a huge post on that very subject. Below is my post, edited to incorporate additional information from his presentation yesterday.

First, let's start with a bit of fun:


The thrust of Dr. Roger's presentation was a refutation of progressive creationism. I'd not heard that specific term before. It's a form of Old-Earth creationism that accepts the earth's geologic timeline and fossil record, but posits that though species may change into other similar species (e.g., coyotes, wolves and foxes may have a common ancestor), they cannot change from one major "kind" to another (e.g., amphibians could not have evolved from fish).

In progressive creationism, god originally created several "kinds" of organisms which have evolved into all of these species we see today, but are unable, for some unstated reason, to change beyond some unstated threshold.

Where the lines between one "kind" and another lies I suppose depends on the progressive creationist you ask. Are bears and foxes of the same "kind?" Bats and lemurs? What about turtles and alligators? Carrots and plums? Each of those pairs is FAR more alike than they are different, and yet there is no denying that they are also all quite distinct.

According to creationists, the fossil record fails to show an evolutionary relationship between species or "kinds." This argument reaches it's ridiculous extreme in Ray Comfort and Kirk Cameron's silly "crocoduck." The misconception here is that creationists expect to see a "tweening" fossil: something that looks half like an ancestor, and half like a decedent. But it's important to remember that every animal, every "transitional" form is itself a fully-evolved species that is not, from it's own perspective, on its way to becoming anything. A duck's lineage may have encountered innumerable different environmental conditions, developed unique traits, lost them again, and developed new ones on its way to becoming a duck. We HAVE found numerous "crocoduck" transitional fossils between therapod dinosaurs and birds. Take for instance, this cute little guy:

He's a bird-like dinosaur, about the size of a turkey, and he'd gladly rip your face off. You may have heard of him before: velociraptor. Though thanks to Jurassic Park, that name is often mistakenly applied to his big sister, Utahraptor. At the time of the first Jurassic Park film, we didn't know that Utahraptor had any feathers. But since then, we've learned that they not only had feathers, but were likely covered in them and may have looked something like this. Mei long. Deinonychus. Archaeopteryx. Rahonavis. Dozens upon dozens of bird-like therapods and and therapod-like birds. That's a lot of crocoducks.

The evidence continues to mount showing not only that birds evolved from dinosaurs, but in many ways, birds are dinosaurs. (For a decent sumamry, check out the Wikipedia articles on Origin of Birds and Bird Evolution.)

In last night's presentation Dr. Rogers focused not on bird evolution but on whales. Since whales are mammals, they must have evolved from land mammals, right? Well, shouldn't we see transitional forms in the fossil record, becoming more and more adapted to aquatic environments?

Yes, we would expect to see transitional forms like this.

And guess what? We do! Indohyus. Pakicetus. Ambulocetus. Rodhocetus. Dorudon. Just this month, a new important fossil in the whale lineage was announced: Maiacetus (you can even read the original paper describing the discovery and its implications).

But what evidence would it take to convince a creationist that evolution had occurred (or in the case of progressive creationists, that is occurred between ill-defined "types")?

I'm willing to bet that for most creationists, the answer is no amount of evidence. The beauty of the "no transitional fossils" argument is that it can be applied infinitely: Any time a "gap" is filled with a newly-discovered fossil, the creationist, rather than seeing a closing gap, will now see TWO gaps that need filling. If he asserts that there is a gap between species A and species C, then you discover species B, now you have a gap between A & B and B & C. Isn't that handy?

In addition to the fossil evidence for evolution, Dr. Rogers talked about the molecular evidence. If fossils show a reasonable and convincing path for evolutionary change, then the molecular and genetic evidence is a blaring neon sign stating "evolution has occurred here!" But I'll save that for another post.