Civilisation has left its mark on our genes

catholics are being majorly selected. scientists, especially those who practice abortion, are not...Its all sort of ironic.

Only about 30% of humans produce lactase into adulthood. This enzyme breaks "milk sugar", lactose, in to glucose and galactose, both of which the body can digest. Without lactase, lactose is ignored by the body and is digested by gut bacteria instead, leading to gas, bloating and often times severe bowel irritation.

All other humans -- all other mammals, in fact, including all other primates -- stop producing lactase about 5% of the way in to their expected lifespans (for humans, between 2 and 3 years old.) This is a positive evolutionary adaptation, as it forces the young animal to wean, thus freeing the mother to nurture other young.

It seems that the mutation to keep producing lactase occured three different times. The European mutation is most widespread and is found in most people of European extraction. It is also found in India up in to the Himalayas. The smallest population is the Massai in Africa, the only population indigenous to the continent able to eat milk products in to adulthood. It is entirely absent from other human populations, except where it can be traced to one of the other groups.

Such a mutation relies on the domestication of milk-producing animals. Domestication of animals is one of the hallmarks of "civilization." It is therefore reasonable to say that the lactose tolerance mutation shows that civilization has left its mark on the human genome.

I remember seeing a documentary about some West African desert ethnic group that also lives largely on dairy products.

Also, some groups have a tradition of fermented milk products, such as the Mongolians, who drink something made of fermented horse's milk. (I've read a description of it as tasting like "spiked buttermilk.")

But right, the ability to drink straight milk products is not universal. The Japanese of today are taller and less liable to osteoporosis than their ancestors, and one reason is the addition of yogurt, cheese, and other calcium-rich foods to their diets in the postwar years. When I first went there in 1977, there were a lot of extremely tiny elderly people who were bent nearly double. You don't see nearly as many today.

And the Indian version of the mutation is the same one found in the Himalayas.

Also, there are dairy foods that contain little to no lactose, as the milk sugar is consumed by bacteria or mold. Many lactose intolerant people are able to eat hard cheese and yogurt in moderation. I've developed lactose intolerace over the last two years, and while I still enjoy blue cheese on occasion, I have learned (quite the hard way, I assure you) not to put cream in my coffee, to have eggs rather than cold cereal for breakfast and to use margarine on my toast.

On the upside, I now have great rejoinder when co-workers call me a mutant. :rofl:

The West African tribe that lives on dairy products is in the Sahel somewhere.