Sunday, January 27, 2008

The Fish With Arm Bones

Tiktaalik rosae is the name Neil Shubin's team gave a fossil they found in the Canadian Arctic a couple years ago. Shubin's book, Your Inner Fish, describes the dig and the excitement that surrounded the discovery of what Shubin calls a "fishapod".

The book is a great read - full of evolutionary and embryologic connections. You'll learn where spines and skeletons come from, what genes we share with our insect and worm relations, why hernias and knee injuries have come to plague the human species. You'll learn all about how gill arches turned into inner ear bones and throat cartilages, how head bones form, why the development of a mobile neck (present in Tiktaalik) was a revolution in evolution (it freed the upper limbs to do one thing while the head did another).

I was hoping for a fuller examination of the evolution of the nervous system, but alas, such an examination was beyond the scope of this book apparently. There are a few tidbits on brainstem function and central pattern generators, and why the phrenic and vagus nerves emerge so soon and dangle dangerously outside the spinal column before reaching their destinations.

It is hard to put this book down if you have any sort of interest in the human body, whether it is a third-person or first-person interest. It will leave the reader feeling an integrated part of all nature through time. I recommend reading it together with Into the Cool (much of which is available free online in the link provided) and dazzle gradually, both of which are co-written by Dorion Sagan. For more about the evolution of the nervous system itself, Up From Dragons is a fairly good read, yet another Dorion Sagan co-write. (How can you tell I'm a big Dorion Sagan fan?)

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