Category Archives: Dairy

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.

Only a Third of the World’s Adults Can Digest Milk

Nature has in interesting article on Neolithic dairying, lactose intolerance, cheese, yogurt, and the spread of genes that allow for lactose digestion. The ability to digest milk in adulthood—called lactase persistence—is less than 40% in Greece and Turky, but higher than 90% in the UK and Scandinavia.

During the most recent ice age, milk was essentially a toxin to adults because — unlike children — they could not produce the lactase enzyme required to break down lactose, the main sugar in milk. But as farming started to replace hunting and gathering in the Middle East around 11,000 years ago, cattle herders learned how to reduce lactose in dairy products to tolerable levels by fermenting milk to make cheese or yogurt. Several thousand years later, a genetic mutation spread through Europe that gave people the ability to produce lactase — and drink milk — throughout their lives. That adaptation opened up a rich new source of nutrition that could have sustained communities when harvests failed.

Read the rest.

Natural Selection and the Origin of Cheeses

Vitruvius at The Sagacious Iconoclast explains why cheese is an unlikely Paleolithic (Old Stone Age) food:

I was recently involved in a discussion in which some folks were attempting to distinguish between what they were calling “processed” cheese and other (presumably non-processed) cheese, without defining what they mean by “processed” cheese. As I think that’s a less than optimal approach, I’d like to take a moment to sketch out why that is so; perhaps increasing, in the process, your enjoyment of cheese forever.

Neolithic Cheese

Vitruvius suggests one way prehistoric man could make cheese: “transport milk in mammal stomach vessels containing natural rennet, in the heat, thousands of years ago, and voila: curds and whey.”

It’s a moderately lengthy article, but well worth it for the amusement and erudition.  You’ll learn how cheese is made, starting with the photons.

Steve Parker, M.D.