Posted by The hit parade of creationist responses to Tiktaalik roseae continues with this article about the response of Ken Ham, founder of the American wing of Answers in Genesis. Like the rest, it’s amusing for the almost total lack of any substantive response to the facts.
“If you look at a platypus, a platypus has features of reptiles, birds, and mammals,” he notes. “Now, that’s not considered to be a transitional form. But what you find is that God has used optimum features in different creatures. And so you see some similarities and you see differences, and so on — just as the forelimb of a human is similar to the forelimb of a chimp is similar to the structure of the bones in other animals, other vertebrates.”
The fossil — which Ham describes as a lobe-finned fish — is just another example of God’s divine design, he says. “They’re saying that it was evolving legs. But, you know, you’ve got a shallow water fish here, like the lungfish,” says Ham, “and they have the strength in their fins — these lobe fins. They’re different from fins of other fish.”
Well, he’s right that the platypus is not considered a transitional form but he doesn’t say why that is because it would undercut his argument. See, he wants you to think that scientists will call anything that has a mixture of traits a transitional form, but that isn’t the case. In order to be a potential transitional form, it not only has to have an intermediate morphology, it also has to be found in the correct temporal and anatomical sequence. It’s the pattern of appearance that documents a transition, not the mere existence of a species with a mixture of traits from two groups.
In the case of the fish to amphibian transition, we’re talking about the very first amphibians to appear on the earth. Prior to about 365 million years ago, there were no amphibians on this planet, no terrestrial animals at all other than insects (which had only appeared about 400 million years ago). The earliest amphibian tetrapods looked remarkably like lobe-finned fish, called sarcopterygians, which led scientists to posit that they probably evolved from a species in that group.
But it doesn’t end there; we can get more specific. The earliest amphibians were not just closest to lobe-finned fish but to a particular subset of those fish known as osteolepiform. Osteolipiform fish share a trait with amphbians called a choana, an opening between the nostrils and the mouth that is essential for breathing air. In the water, it’s used for smell, not for breathing, but it allows air to pass into the body through the nostrils so on land it could be adapted for breathing. Amphibians and osteolipiforms had them, but other forms of lobe-finned fish did not.
So the ancestor could further be narrowed down to a species that was both sarcopterygian and osteolipiform. And of course, we could identify the time frame (just prior to the first appearance of amphibians about 365 million years ago) and have a pretty good idea what a transitional form must have looked like by comparing the later osteolipiform species to the first amphibians and viewing which anatomical changes had to take place. This is an excellent example of how scientists use predictions to test hypotheses. And as it turns out, Tiktaalik fits the bill perfectly and was found right where it was predicted to exist.
So Ham is in fact attacking a straw man. He’s arguing that just because an animal has a mixture of traits doesn’t mean it’s transitional. But of course, scientists know that and don’t claim that any animal with a mixture of traits is transitional. It’s the pattern of appearance, not just of one species but of several, in the correct temporal and anatomical order, that documents a transition. When you add in that criteria, it becomes much more difficult for Ham, a young earth creationist, to explain why we see this pattern of appearance repeated over and over again in the fossil record.
From a young earth perspective, how would you explain why the first amphibians to appear in the fossil record look virtually identical to osteolipiform fish with just a few adaptations? How would you explain the fact that, as new amphibians appear in the fossil record, they become more and more diversified, less like their ancestral forms and more like modern amphibians? Remember, Ham believes that all of the animals found in the fossil record were created virtually simultaneously, in a single week. They all existed at the same time and were all, according to him, buried by the flood.
Yet all over the world we find this very distinct pattern of appearance in the fossil record and it’s not just with amphibians. The first birds to appear look just like theropod dinosaurs with feathers (because, of course, that’s what they were). As new species appear in the fossil record, they gradually become more diversified, less theropod-like and more modern looking. They lose their reptilian teeth, their vertebrae fused (reptiles have unfused vertebrae, modern birds have fused vertebrae), their pelvic girdle and wishbone become better adapted for flight, and so forth.
The same pattern is found in mammals and every other major animal group. And this pattern must be true if evolution is true. If there were any other pattern, evolution simply could not be true. But these patterns are quite inconsistent with the notion that all animals were created in the same week and lived at the same time. And even from an old earth perspective, they’re difficult to explain. Did God just happen to create in just the right order to mimic evolution? It’s possible, of course, but it’s special pleading. It’s only an ad hoc explanation without any evidence, whereas for evolutionary theory it’s a prediction that must be true if the theory is valid.
April 24, 2006
April 24, 2006