Tag Archives: lactase persistence

Diet Implications of Human Origins and Migration

African Savanna

African Savanna

Until 10,000 to 12,000 or so years ago, humans and our hominin ancestors obtained food through a combination of hunting and foraging. We hunted small or large game and birds. At some point we learned how to catch fish and shellfish. We searched for and gathered up fruits, berries, leafy plants, nuts, seeds, mussels, clams, honey, eggs, and roots.

Young woman sitting at camp fire, holding fried sausage

 

The range of edible items expanded when we harnessed the power of fire for cooking, which was at least 230,000 years ago and may have been as long as a million years ago.Tools and weapons also expanded our possibilities from the very start of the Paleolithic.

 

Prior to 10,000 years ago, we weren’t farming or raising cattle and dairy cows. Available foods depended on local climatic conditions, soil, and water availability. Climate, in turn, is heavily dependent on latitude (how far away from the equator) and altitude. East Africa at the dawn of humanity is described as savanna: grass-filled plains with scattered patches of forest, and relatively dry. Plants and animals available there would be much different than the colder but wetter Europe 200,000 years ago.

Steve Parker MD, paleo diet, paleobetic

Nubian ibex in Israel

 

Humans in Northern Europe tended to eat more animal-based food and relatively less plant matter than savanna-dwellers, perhaps just because there were fewer edible plants growing in the cold climate. Many plants would have been highly seasonal, just as they are now.

Tribes of humans walked or migrated to nearby micro-climates as one plant went out of season and another came into season. Tribes followed prey animals as they also migrated in search of seasonal food.

Due to technological limitations, we wouldn’t have been able to utilize some potential food sources that required much processing, such as cereal grains and legumes. Since we weren’t yet pastoralists (raising sheep, cattle, etc.), we would have access to milk only if we killed a nursing prey animal. Have you ever tried to milk a wild water buffalo? Not advisable. Ability to digest milk beyond infancy was marginal. Even today, two-thirds of humans lose the ability to digest milk after infancy.

The experts debate actively debate how long we’ve been consuming significant amounts of cereal grains and roots. Canadian researchers working in Africa suggest we’ve enjoyed them for over 100,000 years (see Mercader, Julio, et al. Mozambican grass seed consumption during the Middle Stone Age. Science, December 18, 2009.)

Steve Parker, M.D.

How Fast Are Humans Evolving?

paleo diet, Steve Parker MD,calcium, osteoporosis

I’m guessing she’s northern European, perhaps Irish

Most paleo lifestyle proponents think that, genetically speaking, those of us living today are pretty much the same as our ancestors living 50,000 or even 200,000 thousand years ago. That may not be the case.

Conventional Wisdom

The traditional view of the rate of human evolution’s is articulated by Artemis P. Simopoulos, who was with The Center for Genetics, Nutrition and Health in 2009 when he wrote: “The spontaneous mutation rate for nuclear DNA is estimated at 0.5% per million years. Therefore, over the past 10,000 years there has been time for very little change in our genes, perhaps 0.005%. In fact, our genes today are very similar to the genes of our ancestors during the Paleolithic period 40,000 years ago, at which time our genetic profile was established.”

Evolving Thought

 

On the other hand, the experts are debating now whether the pace of human evolution has accelerated over the last 10,000 years. The iconoclasts say it has. For example, remember that most mammals lose the ability to digest milk after they’ve been weaned off the teat in early life: they lose the lactase enzyme that allowed them to digest milk sugar (lactose). That’s why lactose intolerance is so common among adult humans—only a third of us worldwide can digest milk. Five or 10,000 years ago, a genetic mutation occurred that allowed those possessing the gene to consume and digest milk. So a whole new source of food for adults opened up: dairy cattle. Would that have conferred a survival advantage? You bet. We have evidence that the milk-digesting mutation spread fairly quickly since its appearance. But it hasn’t spread across the globe uniformly. The ability to digest milk in adulthood—called lactase persistence—is less than 40% in Greece and Turkey, but higher than 90% in the UK and Scandinavia.

Another oft-cited example of rapid and recent human evolution is the appearance and spread of blue eyes starting six to 10,000 years ago. Everyone with blue eyes today apparently has a common ancestor that had a gene mutation back then, when everybody had brown eyes.

For more information on the “rapid evolution” idea, check out the writings of Gregory Cochran, Henry Harpending, and John Hawks. Also consider a new book by Nicholas Wade, “A Troublesome Inheritance: Genes, Race, and Human History.” Wade is a science writer for the New York Times.

Steve Parker, M.D.