Wednesday, March 04, 2009

What evolution means to me

A professor once became exasperated with my habit of reconciling all ideas about humanity with our evolutionary history. "But people care about much more than reproducing," he demanded.

Natural selection is the simplest and least controversial of the three established categories of the forces driving evolution. The layperson often uses the terms "evolution" and "natural selection" interchangeably, even though the roles of genetic drift and gene flow are no less important.

The simplest implication of the role of natural selection in our evolutionary history is that humans have adapted to reproduce as "efficiently as possible." As evolution is a slow process, taking hundreds if not thousands of years for small changes to appear, we can look to the conditions of humanity in the last several thousand years to gain some understanding of the environment for which our bodies adapted for maximum reproductive effectiveness.

Humans have changed their means of survival and lifestyles so drastically in the last 80 years that evolution has not had time to catch up. The biggest (literally) example of this lag is obesity. Since the vast majority of humanity struggled to find enough food to survive in the last several thousand years, we evolved to store calories readily for leans times. Now, in the age of abundance, obesity is considered an undesirable trait, and could, in principle, reduce the potential for reproduction of those who suffer its effects. Unfortunately, I don't have comparative data on the reproduction rates of the fat and lean.

I care about evolution, and here is why. The modern life is so far removed from our natural history that the lives we live now are not the lives that our bodies evolved to live. Although a historical connection between happiness and reproductive success is not obvious, my intuition strongly suggests that moderately happy people, before the age of birth control, reproduced more than sad ones, which is to say that our happiness is directly tied to our pre-modern lifestyles.

This suggests, gently, that I may be happiest if I live a life that resembles the lives that my ancestors physically and mentally evolved to live. Therefore, as I look for ways lead to a more fulfilling life, I hold in the back of my mind this question: "Where, in the common lifestyles of my ancestors, might I find inspiration for life decisions that will enable me to lead a healthy life by not running against the grain of my genetic code?"

In particular, I am interested in those habits which the extremely recent industrial system powerfully obscures from my everyday thoughts:
  • Several hours of physical labor per day, preferably in the areas of gardening with simple tools.
  • Occasional hunting trips, involving simple projectiles, lots of running, and up-close-and-gory attack.
  • Eating moderate quantities of lean meat.
  • A diet high in roughage and low in processed foods.
  • A lot of time out in the woods and field.
  • Working with my hands for much of the day.
  • Walking long distances regularly.
  • Interacting with people and animals on a regular basis.
  • Doing all of these activities as a means of providing myself with food and shelter.
  • Reproducing.
On this last item, I think my professor was right: People don't have reproduction on the top of their minds. Birth control is so new to humanity that natural selection has not had time to select for the genes of folks who consciously care to reproduce. Until recently it was enough for natural selection to dictate that men should simply have sex on the top of their minds, and that women should prioritize finding supportive friends and/or committed mates. But, as with the rest of the things on the list above, reproducing may benefit our psyches, even if we don't consciously have the urge to do it.

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