Whale teeth and pseudogenic evolution

It seems every day now you hear about new evidence for the theory of evolution, be it from the fossil record or phylogenetic analysis. Well, if you live in the Internet, that is.

The mainstream media is not a massive fan of the real nature of science, “go slow, build up a big picture of the world , while making sure we’ve got it right this time”, unless it involves the odd unexpected discovery, as seen in the relatively recent media explosion over the Darwinus masillae find. Because of this, they often miss out on the cool research that reinforces what we already knew about evolution, but provides an excellent defense against those pesky creationists.

The point of this post, of course, is to highlight one such piece of new research. I chose this one because it teaches a great lesson about how predictions are made in relation to the theory of evolution, and it contains whales. Who doesn’t love whales?

Researchers at the University of Calfornia, Riverside, have recently released a study looking into the loss of enamel in the ancestral lineage of modern toothless whales, by studying the decay of a tooth-specific enamel-producing gene with reference to the existing fossil record.

According to the evolutionary model we currently have, modern toothless whales, such as blue whales and humpback whales, evolved from ancestral toothed whales somewhere around the mid Miocene epoch (23.3 – 5.2 million years ago). When the shift occurred to the modern baleen-filter system, the various genes that controlled either the development of teeth and/or the production of specific proteins involved with the parts of the tooth structure lost their expression through mutational decay.

This study focused on one gene, the enamelin gene, which expresses the enamelin protein. Mammals that do not express this protein, such as toothless whales, lack enamel on their teeth (if they have teeth at all), the hardest substance in the vertebrate body, which caps each individual tooth. Evolution predicts that in order to have evolved from toothed ancestors like the fossil record suggests, modern toothless whales must contain a copy of this gene in their genome, yet it will be inactive due to the slow build-up of detrimental mutations over time – ie. it will be a pseudogene.

Can you guess what they found?

Ooh yeah, score again for evolution! Mark Springer, one of the leaders of the study, said:

We could … predict that nonfunctional vestiges of the genes that code for enamel should be found in mammals that lack enamel. When we made our predictions, however, we did not have sequences for the enamelin gene in toothless and enamelless mammals. Since then my lab worked on obtaining these sequences so we could test our prediction.

In our research we clearly see the parallel evolution of enamel loss in the fossil record and the molecular decay of the enamelin gene into a pseudogene in representatives of four different orders of mammals that have lost enamel.

So, working from a state of limited knowledge about the genome, the researchers made predictions about what they should find, collected the data, analysed it, and found what they predicted was correct.

Remember, if evolution did not occur to produce the diversity of life that we see today, and life was created by an intelligent designer, vestigial genes such as the enamelin gene in toothless whales should not exist in any genome. Intelligent design proponents and creationists like to skirt around the issue and claim that some or most pseudogenes are actually functional, but this is untrue. Even if some pseudogenes have gained a function, it still does not discount them as being vestigial remains from early generations.

Will the Discovery Institute comment on this research? I’m not sure. They’re all up in arms at the moment over Richard Dawkins’s new book, The Greatest Show on Earth, so coverage of a new evolution paper that they could quite easily ignore might be asking a bit much from those guys.

Whether or not they decide to attack it, the research still stands as great evidence for evolutionary theory. I fully expect more research like this to continue to come out, as other morphological changes in the fossil record are examined against pseudogene data.

Update: Turns out that the Discovery Institute have released a “statement” (read: blog post) about this study. Guess what? They missed the whole point of the study:

Their conclusion?

“Our results link evolutionary change at the molecular level to morphological change in the fossil record and also provide evidence for the enormous predictive power of Charles Darwin’s theory of descent with modification.”

Enormous predictive power? Really? It seems to me that if there is any “power” to Darwin’s theory, then it must come from its ability to demonstrate how new structures arise, not how previously occurring structures disappeared.

Err, this study was about phylogenetic predictions, guys, not about positive morphological change. Don’t strawman a study you clearly don’t even understand.

Am I allowed to facepalm? I think I will…