Wednesday, June 20, 2007

What's so natural about natural selection?

Sometime back about 25 million years ago, our ancestors among the primates lost their tails. Not quite sure what caused this turn of events. Did it have to do with coming down out of the trees? Gibbons have no tails and they are wonderfully arboreal. Many ground-living animals sport posterior appendages. Whatever the reason, I think it a great loss. I would love a bushy tail, maybe something as attractive as that of the ring-tailed lemur, but I suppose that having lost most of our body hair we would be more likely to have a rat-like tail, not nearly as nice.

And what about body color? Primates have excellent color vision, and more than any other animals use color for sexual displays. Mandrills, vervets, drills and langurs have great fun flashing their gaily-decorated "private" parts. My goodness, humans are a pallid species. How about a nice electric blue penis? Or a pink and green striped heinie? When it came to color, we surely got shortchanged.

If tarsiers and bushbabies are any indication, it seems that 60 million years ago our common ancestor may have had great big eyes, terrific for seeing in the dark, but also terribly cutesy in a Keane sort of way. Just look at the bushbaby here; what a sweetie! I'd take those big saucers any day over our squinty little human eyes.

There are good reasons, presumably, why natural selection gave us the features we have, but there is obviously also a lot of arbitrariness in evolution. Put a slightly different spin on things and I might have ended up with a sleek honey-golden pelt, a fuzzy tail, a penis as green as a Brazilian flag, and big, big, bushbaby eyes with curly lashes. Now wouldn't that be nice.

(Newcomers to Science Musings are welcome to visit a primate family reunion we held a couple of years ago.)