An Evolutionary Problem

Recently I picked up a copy of Charles Darwin’s masterpiece, “The Origin of Species.” After all, it is hailed as one of the greatest turning points in science, if not biology. It essentially lays the basis for a lot of my own personal work in genomics. Right now, I’m about halfway through the book. Interesting read so far.

While away on a genetics conference last week, I was ambling around the San Diego Zoo. I walked by elaborate monkey and gorilla exhibits. Then I made an interesting observation. It may sound a bit obvious to some, but I never gave it much thought before. How is it that we, humans, are functionally so different than any other species that roams the earth? Genetically, we’re fairly close to apes. In fact, chimps are purportedly closer to Homo sapiens than they are to any other species. Yet, phenotypically — examining our own physical traits and expressions — there is not a single species that is even remotely like us.

Anthropologists have an answer to this supposed quagmire. We developed opposable thumbs as well as a language, and that sets us apart from other creatures. These traits have put us on a trajectory to intelligence and technology. In addition, the fossil record indicates the existence of other homonids (Homo erectus, Homo habilis, etc.), but they are now extinct. While a valid answer, my question is: why are these other homonids extinct? According to Darwin, a favorable trait that is naturally selected will likely be expressed in close varieties of the species where that trait originated. Why is it, then, that no other existing animal species have opposable thumbs or a well-developed language? Why are there no intermediate species between chimps and humans, who might have opposable thumbs, but speak very poor English? Why haven’t other species developed, or at least borrowed from humans, tools for hunting, rummaging, fighting? If Darwin’s conjecture is correct, then there should be other human “varieties” roaming the planet.

It just strikes me as odd that, given the success of our species and the existence of countless other species, there aren’t any close runners-up. No other species seems to have a conscious drive to excel like we do. The gorillas and the bonobos seem quite content in the little habitat the San Diego Zoo has carved out for them.

But these are just some points I’m pondering over as I’m reading the rest of “Origin.” After doing a bit of digging on the ‘net, it seems that Darwin’s follow-up, “Descent of Man,” might specifically address this question.

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genetics, evolution