Tuesday, February 4, 2014

What's so bad about ag? (Searcher)

People are obsessed about what they eat. And for good reason. Much of the western world’s current medical crises (Type II diabetes, heart disease) can be directly linked to poor diet.  More recently, research into the “ancestral diet” has given us a better understanding of what humans 100,000 years ago ate. Nutritionists have since used this research to model new diets to better reflect what it is humans must be genetically programmed to eat (e.g the Paleo diet). A myth, it seems, has been created that claims we are maladapted to the modern society (even to agriculture), and that we should be striving to emulate the conditions are ancestors evolved in (at least when it comes to diet and exercise).

But here’s the thing: humans haven’t stopped evolving.

Sure, evolution is slow. It can take hundreds of generations for a mutation to get a handhold in a population, and even then it can be wiped out by drift in half the time. There are examples in humans, however, that demonstrate that we are capable of adapting to a changing environment relatively quickly, especially when it comes to what we eat. Two prime examples are changes in two enzymes: lactase and amylase.

Given that humans start off consuming their mother’s milk, babies need a lot of the enzyme lactase to digest a prime ingredient of milk, lactate. Once a baby is weaned, the body stops producing the enzyme and redirects that energy into other biological processes. When humans began domesticating cows and, subsequently, drinking their milk, natural variation in the population favored people who continued to make the enzyme into adulthood because of the nutritional value associated with milk and dairy consumption. Our genes adapted when our diet and lifestyle changed1.

The story is similar with amylase. Amylase is the primary enzyme responsible for breaking down starches. When human populations switched to an agricultural-based society, so did their consumer of foods containing high amounts of starch. In response, the copy number of a gene coding for amylase increased (that is, more amylase was being made)—another adaptation that stuck.2

While it’s unlikely our bodies will adapt to thrive off of sodas and Big Macs, you do have to give evolution a little credit and realize that humans can, in fact, change with the times.

(And check out the TEDtalk below for the ultimate in human evolution: cooking.)

1.    Got Lactase?”

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