Evolutionary biologist Marlene Zuk wrote a great essay in today's New York Times titled "The evolutionary search for our perfect past," in which she focused on the fallacies of assuming that all of today's supposed health woes (specifically those many people relate, accurately or not, to nutrition and obesity) would be remedied by our Pleistocene past.

But the difficulty with using our hunter-gatherer selves as icons of well-being goes much deeper. It is not as if we finally achieved harmony with our environment during the Pleistocene, heaved a sigh of relief and stopped.

In fact, Pleistocene humans might not have been any more in sync with their environment than we were, as the mass extinction of large mammals (megafauna) in both North America and Australia coincided with the arrival of humans.

Nor were all so-called "caveman" diets identical. Zuk points out that the relative ratio of meat to plants varied depending on local resources, making such books as "NeanderThin" all that much more ridiculous. A recent discussion on Shapely Prose further elaborates on this assumption that cave-people were somehow the epitome of thinness and health.

Concludes Zuk:

Instead, evolution lurches along, with successive generations sometimes unchanged, sometimes better suited to their surroundings in some ways but not others. At any one point, adaptations take place: individuals who can endure heat or cold or famine leave more offspring than their less hardy counterparts. But there is no one point when one can say, “Voilà! Finished.”

...We have never been a seamless match with the environment. Instead, our adaptation is more like a broken zipper, with some teeth that align and others that gape apart. The paleontologist Neal Shubin points out that our inner fish constrains the human body’s performance and health, because adaptations that arose in one environment bedevil us in another. Hiccups, hernias and hemorrhoids are all caused by an imperfect transfer of anatomical technology from our fish ancestors.

This isn’t to say that we wouldn’t be better off eating fewer processed foods. And certainly we have health concerns that never struck our ancestors. But we shouldn’t flagellate ourselves for having modern bodies, and we shouldn’t assume that tweaking our diets or our posture will rescue us from all our current ills. That’s just a paleofantasy about the future.

Our bodies are naturally imperfect; evolution works with what exists and builds on it*. Perfect health and immortality are pipe dreams and not rooted in reality. Our bodies are amazing things, no doubt about it, but perfection ain't possible.

*As a staunch evolutionist and anti-creationist/anti-intelligent design-ist, I think this is some of the most powerful evidence we have for evolution- the lack of perfection.