Posts Tagged ‘human evolution’

Communing with your inner fish

September 3, 2008

Continuing (and concluding) my series entitled “Books I Bought in Seattle,” I will now regale the reader with my impressions of Neil Shubin’s recent book, Your Inner Fish.

The book is an exploration of the history of human evolution, in the only place available to us: the bodies of other animals, extand and ancient. Shubin points out the one-to-one correspondence between the bones in our limbs, and the limbs of all other tetrapods, to those of the Devonian fish he helped discover, Tiktaalik. He describes how the general body plan of vertebrates was in place 550 million years ago in the Cambrian, and perhaps even in the Precambrian, as evidenced by the famous Ediacaran fossils. He similarly explores the evolution of vision, of hearing, of the sense of smell, and points out how all our wonderfully complex sense organs have analogues in far more (seemingly) humble creatures.

Shubin’s lively and playful writing captures the breathless excitement that surrounds each new scientific discovery, and I delighted in his accounts of the findings that shaped our knowledge of evolution. He succeeds in portraying scientists as ordinary people, whose job happens to be probing the underlying nature of the universe. I have to thank him also for his clear explanation of the gene Sonic hedgehog. The only complaint I would level against it is that I fear he sometimes dumbs down his accounts too much; there was more than one place in the book that I felt would benefit from the actual terminology, rather than a more general explanation by analogy. But this is a minor complaint, as evidenced by the fact that I did not provide an example.

The fundamental theme of the book is that, as remarkable as we are, we are an inextricable part of the tapestry of life, no more and no less remarkable than anything else that lives. Everything that makes us what we are is derived from something that ran or flew or swam upon the Earth before. Within each of us is an inner fish, and an inner ape, and an inner reptile, and an inner bacterium (trillions of these, actually); reading Shubin’s book is an excellent way to gain acquaintance with them. (Richard Dawkins’ The Ancestor’s Tale is another.)

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Human lineage nearly split

April 27, 2008

BBC News has a pretty cool article on some research published in the American Journal of Human Genetics. The claim is that there was an early split between two populations of Homo sapiens early on, and the two populations persisted in isolation for about 100,000 years. Apparently this wasn’t long enough to achieve reproductive incompatibility, because the populations later intermingled, and we’re left with a single species.

This kind of research always kicks off my imagination. What if speciation had occurred between those two African populations? What if they each began the slow march across the world? What if today, we had two separate, reproductively incompatible populations of sentient animals?

According to our modern sensibilities, there is really only one kind of human animal, and we are all essentially the same to a reasonable approximation. A human being from any part of the world can travel to any other part, and barring any cultural conflict, can learn the language of the people, pick up the customs, perhaps even start a family and produce fertile offspring. Our entire concept of ourselves revolves around our notion that there is only one kind of sentient animal on Earth.

What if there were two? What if there were an entire species whose language was forever impenetrable to us no matter how we tried to learn it, because of differences in brain structure? How would we interact with animals like that? Would we consider them beneath us? Would they consider us beneath them?

I don’t know. I could spin out a dozen more questions on this topic, but very few answers. The history of human evolution is a fascinating line of research.