Monday, April 4, 2016

Evolving, Not Evolving

I'm fascinated by the question of whether humans are still evolving or not, and even to what extent all humans are basically the same (aside from the obvious misdirection of skin color, hair type, and other superficial attributes). We all make the same "no" face, for instance. How cool is that?

The "no" face

Well, here's one way that we are different: there appears to be a genetic basis for the ability to be a healthy vegetarian, just like there is a genetic basis for lactose tolerance. This Washington Post article, reporting on research at Cornell University, told me some cool facts:

  • "Omega-6 contributes to inflammation and plays an important role in skin and hair growth, bone health and reproductive health. Inflammatory responses are essential to our survival. They help fight off infections and protect us from injury. But if the response is excessive, it can lead to all kinds of problems and may contribute to a higher risk of heart disease, cancer and Alzheimer's disease. Studies have suggested that humans evolved on a diet with a ratio of omega-6 to omega-3 essential fatty acids of 1:1 but that the Western diet has a ratio that is closer to 15 or 16:1."
  • "[Researchers] analyzed information from the 1,000 Genomes Project — a database of global DNA — to calculate an estimate of the frequency of the vegetarian allele in far-flung populations around the world. The differences were striking: 70 percent of South Asians, 53 percent of Africans, 29 percent of East Asians and 17 percent of Europeans had the gene variation."
  • "Ye and colleagues found a different version of that gene adapted to a marine diet, rich in seafood, among the Inuit people in Greenland. Technically speaking, it’s the 'opposite' of the vegetarian allele. The vegetarian allele has an insertion of 22 'bases,' or a building block of DNA, and this insertion was deleted in the marine allele. Ye…theorized that having the vegetarian allele 'might have been detrimental' for the Inuit because of their seafood-rich diets." Which is eyebrow-raising for anyone who has been lectured by paleo diet fans about the healthfulness of the high-fat Inuit diet for people in general.
  • "The vegetarian and marine alleles appear to control the FADS1 and FADS2 enzymes in the body, which are critical to converting omega-3 and omega-6 fatty acids into what the researchers called 'downstream products' needed for brain development and controlling inflammation. People who eat meat and seafood need less of the FADS1 and FADS2 enzymes to get sufficient nutrition. 'Their omega-3 and omega-6 fatty acid conversion process is simpler and requires fewer steps,' they noted." And I understand from all of this that people who have the vegetarian allele are better at converting vegetable nutrients into downstream products than people without the allele.
  • Which ethnic group is most likely to have the gene variant for lactose tolerance in adults? The Irish. Oh, and researchers found the adult lactose variant occurred only 3,000 years ago… it had been thought to have begun 7,000 years ago.

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