Interesting Because Boring

I've been reading Your Inner Fish by Neil Shubin, in the frantic minutes between stopping work on my Owlcon round and falling into a desperate sleep. It's an excellent book about the evolutionary origins of human anatomy, aimed at the layman.

Why is facial anatomy so complicated for doctors in training to learn? Because various parts of the face arise from the first and second gill arches, which have migrated from their simple place at the top of the neck all over the face, dragging nerves and muscles behind them to mark their path.

Neil Shubin is the lead discoverer of Tiktaalik, the fish with wrists you may have heard about last year.

One of Shubin's points about Tiktaalik is that it's scientifically important because it's so completely unsurprising. That is, Shubin's discovery went something like this:

• We know about Eusthenopteron, a Devonian lobefin fish from around 385 mya, with a humerus, but nothing else armlike about the fin.
• We know about Icthyostega and Acanthostega, umambiguous tetrapods (amphibians) from the Devonian about 365 mya, with full legs and feet.
• We're pretty sure, based on Jenny Clack's work on the limbs of the 'stegas, that legs evolved to help move around shallow water, so you want to look in river deltas and floodlands.
• So we want to look in Devonian rocks formed in river deltas and floodlands around 375 mya, and we'll find a lobefin who's turning into a tetrapod.

The oil geologists have surveyed the whole world, so it's pretty easy to just look up "375 mya river sediments", and off to the Arctic went Shubin and his team, where they found Tiktaalik, a shallow water lobefin fish with an arm and a wrist, but not a foot.

It was exactly what they expected, exactly where they expected to find it. Practically boring, but precisely because of that, it's a triumph for science.

To quote XKCD: Science. It works, bitches.

Posted by Greg at January 23, 2008 10:22 AM