"...a paleofantasy about the future."

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, “VoilĂ ! 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.

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Cammy said...

I am so glad to see attention being given to the myth that the "all natural" diets/lifestyles of the past were much better for us. True, the lack of added sugars, chemicals, etc undoubtedly was better in some ways, but paleoanthropologists almost always find evidence of some kind of nutritional deficiency, chronic disease, etc etc in prehistoric human remains. And those are the people that actually survived childhood, no mean feat. Also, for those that think we're perfectly designed, I hope they never have to have their appendix or wisdom teeth removed, or have back surgery, or a hernia, or bum knees, the list goes on and on and on...

I was a little disappointed in Shubin's latest book, though. It was well-written but most of the examples are ones that have been used and re-used for a long time. I would recommend it for someone without a really strong science background, though.

Cammy said...

By the way, I highly recommend the book Survival of the Sickest! I read it a couple of months ago and LOVED it.

Carrie Arnold said...

Agreed- on both books.

marcella said...

Life, at least until the 20th Century, and then only for the affluent West, has nearly always been nasty, brutish and short. I'm not biologist, but a quick glance at history will tell you that. The "diseases of affluence" including those linked to obesity, can only flourish now because people live long enough to develop them instead of dying in agony from diarrhoea as an infant, or diphtheria aged 6, or in childbirth, or of septicaemia after a minor workplace accident.

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I'm a science writer, a jewelry design artist, a bookworm, a complete geek, and mom to a wonderful kitty. I am also recovering from a decade-plus battle with anorexia nervosa. I believe that complete recovery is possible, and that the first step along that path is full nutrition.

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