Thursday, June 11, 2009

Why we cook

Middle class folk from industrial countries don't worry too much about the major macronutritient diseases that kill millions (mostly children) throughout the world. Instead, we continuously argue about the proper proportions of macronutrients - our carbohydrates, fats, and proteins - the form these should come in, and how best to prepare them. So we have low-fat diets, Atkins diets, various flavors of vegetarianism (those that consider fish vegetables and those that consider fish animals), various flavors of carnivorous diets (red meat v. no red meat), vegan diets, the paleo diet, raw food diet, etc., etc,. etc.

Too much to blog about in one post but I will make one comment on any diet that purports to be "natural" or more in tune with our "nature" or "evolutionary past". The health claims of these diets assume that humans have not evolved since the pleistocene, that is, back when we were gathering nuts and scavenging lion kills on the African savannah. But there is a huge new research program in human evolutionary genetics that documents pervasive genetic adaption over the last few thousand years. The poster child of this phenomenon is the recent evolution of the regulation of the lactase gene, which has allowed both northern europeans and some africans to adapt (via natural selection) to the behavior of drinking milk from farm animals, as adults. Marlene Zuk has a nice essay from the NYT science section from earlier in the year. Note that the recent, accelerated genetic evolution theory is not uncontroversial (although certain instances like the lactase regulation is, indeed, uncontroversial). If you are interested, John Hawkes frequently blogs about this stuff and since he works in this field, his views merit close attention. In his most recent blog, John mentions Richard Wrangham's most recent book that is receiving a lot of interest: "Catching Fire: How Cooking made us Human". A seed interview with Wrangham about his book is short and sweet.

I've put this book on my list, but what I'm really curious is what (if any) selection has occurred in response to cooking?


  1. I know what you mean about evolution and diet....I noticed recently how many people seem to be alergic to peanuts.

    It is crazy as I don't remember anyone having
    problems when I was younger but now they have taken peanut butter out of the school lunch programs........

    Anouther one is Lactose you think it is actually the milk? I'm thinking it might relate to all the things we are now taking out of the milk.....and adding to it.

    Maybe there a reason for the cream?

  2. Ummm. I love peanut butter and eat it daily!

    All humans have a gene for a protein called lactase that is secreted into the small intestine and digests lactose, which is a sugar in milk (and any dairy product). Humans in nearly all populations across the world stop making this protein during early childhood, which makes sense because most cultures do not drink animal milk and are weaned off of the mother's milk at around age 2 or so. But several culture's began dairy farming - in Northern Europe and in some regions of Africa - within the last 10,000 years and a mutation that keeps the lactase gene active past childhood has increased in frequency (that is the evolution). The mutation hasn't reached 100% in these cultures (or their descendents, including most Americans) and people who don't have the new variant are "lactose intolerant" meaning that they cannot digest lactose, which ultimately causes the gas/diarrhea due to the excess water/bacteria.