Saturday, 26 September 2009

The whole tooth

All good scientific ideas have the power to make predictions. When these predictions are put to the test they can testify to the truth of the idea. Here’s an example.

Now most mammals have teeth but some, such as anteaters or baleen whales, don’t. Evolutionary theory suggests that these toothless creatures evolved from ancestors that did have teeth. So here’s the prediction. We should be able to scan the genome of the animals with no teeth and find the remnants of tooth-making genes still present. Its like digging in the sand for the broken relics of a foregone era.

As most people know teeth are covered in a hard outer shell known as enamel. One of the key genes in enamel production is called enamelin. Researchers have looked for the broken pseudogenes of enamelin in mammals without teeth and, as predicted by evolutionary theory, they’ve found them. The family tree above maps it all out.

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