October 3, 2010

Was there yet another lactase mutation in Tibet for yak milk?

One of the fastest evolving regions of the human genome is an enhancer region near the lactase gene, where new mutations allow people to digest lactose -- and thus animal milk -- into adulthood. One wave of such a mutation spread out from the Indo-European homeland, another throughout eastern Africa (both of these related to cows), and still another from the Arabian peninsula (related to camels).

These three independent waves were all started by nomadic pastoralists, not farmers or hunter-gatherers. Most of the latter don't own livestock to milk in the first place, and when farmers do, they can find other ways around the problem of lactose in their animals' milk -- like letting it age into cheese. Fine for sedentary farmers, but not for on-the-go herders who may get milk into the butter stage but can't stay put long enough to culture it into 5-year aged cheddar. They need to consume it now.

I wonder if there isn't another independent mutation among Tibetans, who have historically led a nomadic and herder lifestyle and whose diet apparently is chock full of dairy from the yak. Check this out: dozens of cups per day of butter tea, which has not only yak butter but yak milk -- and salt! Somehow I doubt all those hummus-and-granola hippies making their pilgrimage to Tibet will share the news of how much saturated fat and salt their favorite oppressed people wolf down all day.

The lactose content of yak milk is the same as for other dairy animals, so any of those three waves of mutations in western Eurasia and eastern Africa would have thrived if they'd gotten into Tibet. Only problem is getting into Tibet. Thus, if lactose tolerance is spreading there, it's probably an indigenous mutation. Just googling around, I couldn't find anything, but Tibetans are not a popular group for genetic study, except for genetic adaptation to the air pressure at such high altitudes.

But air quality isn't the only thing that affects your Darwinian fitness in the mountains. Because jackshit grows that high up, you're probably going to rely a lot more on herding robust animals and, not wanting to kill them too often for their meat, stealing their more replenishable store of milk.


  1. Hemp seeds are 25% protein (a peanut is 25% protein also). Hemp flour is 41% protein. Hemp seeds supposedly have the complete amino-acid profile. Ive never tried them, but have read about them being used as a protein source among vegetarians (we have a vegetarian in our family, a genuinely nice guy).

    I know that peanuts are inflammatory due to the Omega 6/Omega 3 fatty acid balance therein. They are a good source of protein though. I eat em' as a snack myself.

    Its hard to stop eating pistachios if you peel the shells yourself. The pericarps, if salted, taste particularily good with them. Ive had some pre-deshelled pistachios and they weren't as good for some reason. Maybe mentally having to "get at" the pistachio makes you jones for it more. Maybe the pistachio is running game on us all when we have to peel the damn thing, making us want it more.

    Pumpkin seeds are 14% protein, and supposedly very good for you.

    Watermelon seeds are 35% protein. Thats awfully high.

    Sesame seeds are 20% protein.

    Sunflower seeds suck, and even if they were the nectar of the gods, I'd still not like them.

    I looked some of this stuff up because we have a vegetarian in our family now. I like him (we all do). Im not going to give up eating meat unless I become very poor, but he worked in a slaughter-house/meatpacking facility in college, and was pretty disgusted by what he saw. He gave up meat. He told me you simply would not want to know whats in a hot dog.

    One "nut" fact that always intrigued me was that Indians used to eat Acorns. They'd get the tannic acid out by leaving them in running water for a day or two. They are 10% protein. There are some country boys in my area who've eaten some of these. They tell me they taste alright.

    BTW----Hazlenut Chocolate milk is literally as good as the real thing in my opinion. Of all the "milk-like-drinks" (Almond, Rice, Soy) that Ive tried, Hazelnut was the best. Ive not had Hemp milk yet. I can't drink mammilian milk anymore (casein intolerance).

    Frozen blueberries/black de-pitted-cherries defrosted for one minute in the microwave are really, really good.

  2. I spent a couple of months in Nepal and had the greatest tasting tea. I recall it having a creamy texture, but not that of butter. Very smooth, and light flavored. The days are warm but evening brings on a quick chill. I am not surprise that your link speaks of drinking 40 cups a day.


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