Posted on 06/01/2005 5:15:57 PM PDT by PatrickHenry
A new Cornell University study finds that it is primarily people whose ancestors came from places where dairy herds could be raised safely and economically, such as in Europe, who have developed the ability to digest milk.
On the other hand, most adults whose ancestors lived in very hot or very cold climates that couldn't support dairy herding or in places where deadly diseases of cattle were present before 1900, such as in Africa and many parts of Asia, do not have the ability to digest milk after infancy.
"The implication is that harsh climates and dangerous diseases negatively impact dairy herding and geographically restrict the availability of milk, and that humans have physiologically adapted to that," said evolutionary biologist Paul Sherman, a professor of neurobiology and behavior at Cornell. "This is a spectacular case of how cultural evolution -- in this case, the domestication of cattle -- has guided our biological evolution."
Although all mammalian infants drink their mothers' milk, humans are the only mammals that drink milk as adults. But most people -- about 60 percent and primarily those of Asian and African descent -- stop producing lactase, the enzyme required to digest milk, as they mature. People of northern European descent, however, tend to retain the ability to produce the enzyme and drink milk throughout life.
Sherman and former Cornell undergraduate student Gabrielle Bloom '03, now a graduate student at the University of Chicago, compiled data on lactose intolerance (the inability to digest dairy products) from 270 indigenous African and Eurasian populations in 39 countries, from southern Africa to northern Greenland. Their findings will be published in a forthcoming issue of Evolution and Human Behavior.
On average, Sherman and Bloom found that 61 percent of people studied were lactose intolerant, with a range of 2 percent in Denmark and 100 percent in Zambia. They also found that lactose intolerance decreases with increasing latitude and increases with rising temperature, and especially with the difficulty in maintaining dairy herds safely and economically.
A major challenge in interpreting the data, Sherman noted, was to resolve the puzzle that about 13 lactose-tolerant populations live side-by-side with lactose-intolerant populations in some parts of Africa and the Middle East.
"The most likely explanation is nomadism," Sherman concluded. All 13 of the populations that can digest dairy yet live in areas that are primarily lactose intolerant were historically migratory groups that moved seasonally, Sherman said. Their nomadism enabled them to find suitable forage for their cattle and to avoid extreme temperatures. "Also, the fact that these groups maintained small herds and kept them moving probably reduced the pathogen transmission rate."
According to the National Digestive Diseases Information Clearinghouse, some 30 million to 50 million Americans are lactose intolerant, including up to 75 percent of African Americans and American Indians and 90 percent of Asian Americans. Common symptoms include nausea, cramps, bloating, gas and diarrhea that begin about 30 minutes to two hours after eating or drinking foods containing the milk sugar lactose. The use of lactase enzyme tablets or drops or lactose-reduced milk and similar products can help the lactose intolerant digest dairy products.
Sherman's study concludes that adults from Europe can drink milk because their ancestors lived where dairying flourished and passed on gene mutations that maintain lactase into adulthood. The research, he said, is an example of Darwinian medicine, a new interdisciplinary field of science that takes an evolutionary look at health, and considers why, rather than how, certain conditions or symptoms develop. Sherman, for example, recently investigated why spices are used and why morning sickness occurs.
"Both appear to serve an important function to protect the individual," Sherman said. "Spices contain antimicrobial compounds, and they may be used to destroy food-borne pathogens, especially in hot climates. Nausea and vomiting early in pregnancy also may protect women and their embryos from food-borne pathogens and other toxins."
A Darwinian medicinal view complements traditional medicine, Sherman said, because if researchers can better understand why a symptom occurs, such as a fever, runny nose or allergy, they can better evaluate whether it is best to eliminate or tolerate it.
My ancestors come from Europe and get these terrible cramps whenever I hear Democrats talking.
Does this mean Democrats drink more milk than Republicans?
I do. Think of Darwin's finches. Some had long beaks, which assisted them in exploiting a new food supply. They flourished, and passed their long beaks on to the next generation. Instead of beak size, substitute lactose tolerance. Some people had it, and found it advantageous to herd dairy animals. They moved where their animals would thrive. Others, without that genetic tweak, didn't. It's the same principle.
"Seeing this gradation and diversity of structure in one small, intimately related group of birds, one might really fancy that from an original paucity of birds in this archipelago, one species had been taken and modified for different ends."
Source: Journal of a Voyage in HMS Beagle.
I think you've got it right!
Cow's milk contains lactose but goat's milk does not. Cow's milk and cheese derived from cow's milk kills me, but I can eat all the goat's milk feta cheese I want without a problem. There probably are other mammals whose milk does not contain lactose.
Your example is exactly the kind of information that is supposed to make real scientists remember that simple corellation is not causation.
I would bet that you could take a group of children from the predominately lactose tolerant groups. Starting from infancy, get them off of milk at a very young age and keep them off until their mid-twenties. I'd bet they'd be lactose intolerant.
I would bet the population groups that they say are lactose tolerant genetically are simply that way today because their families still use milk as generously throughout their life as their ancestors did. Their gut keeps a healthy supply of the right bugs to digest it, cause they keep milk in their diet. Raise their kids without milk and I'd bet they'd be as lactose intolerant as the Chinese seem to be.
There are those individuals everywhere in the world who are born without the right genes to digest milk ever, even mothers milk. They are the exception. I think the whole thing is what your body learns to respond to from a young age and continuing intp adult hood - for the most part.
I don't want to argue about it but, I disagree. It's more than intestinal bacteria, IMO.
"A major challenge in interpreting the data, Sherman noted, was to resolve the puzzle that about 13 lactose-tolerant populations live side-by-side with lactose-intolerant populations in some parts of Africa and the Middle East. "The most likely explanation is nomadism," Sherman concluded. All 13 of the populations that can digest dairy yet live in areas that are primarily lactose intolerant were historically migratory groups that moved seasonally, Sherman said."
At the beginning of 1700 when the Boers began expanding into the South African interior, they encountered large villages of the Native inhabitants who violently resisted giving up their homes and "grazing" lands. It would seem three centuries ago African Natives had a use for that "grazing" land, maybe like for their own cattle.
Sounds as though it smells pretty good too.
It seems to me that a lot of the little young pup's just out of collage and/or in collage don't know __it, about the history of the world. People in Africa, not only drink cow's milk, but they drink camel's milk, goat milk, and mare's milk. And I guess they have been doing it for year's. So I guess you nailed it.
Thanks for the ping!
"if I can tolerate milk before it's pasteurized but not be able to tolerate if after the process"
Bingo! Pasteurization and homogenation change milk into an unnatural substance. It is no wonder so many have become 'lactose intolerant'. The 'Promised Land', a 'land flowing with milk and honey' does not suggest that milk is a bad thing. But that was not Pasteurized and Homogenized'. Many who are 'lactose intolerant' have found that they can enjoy raw milk, as it comes from the cow.
Pasteurization kills/changes/immobilizes a lot of friendly stuff in milk. Homogenation changes the fat into deadly particles that do nasty things to our bodies if we are foolish enough to drink it. Not all states require that milk be pasteurized, by the way. Any who live where it is legal for raw milk to be sold might want to check it out.
Raw milk keeps longer than the pasteurized stuff. In studies, raw milk causes less illness than pasteurized milk, by a wide margin. Many men with cardiovascular problems have been milk drinkers (pasteurized and homogenized).
Many states that require that milk sold be pasteurized do not require pasteurization for making cheese. This might be why some with an intolerance to milk can eat cheese without a problem. The only thing better than dairy products from fresh, raw milk is if the cows are grazed, not grain fed. Grazed cows produce butter fat that is high in omega 3's, an unsaturated fat that is good for us.
See my post #36. Maybe that's why I don't have a problem with milk but do with cheese. Hmmm?
Most Middle Easterners drank goat milk in the Bible anyway. A person allergic to cow milk usually can handle goat and it's not as mucus forming. Store milk that has been boiled and all the rest is worthless imho.
Here they call fermented milk 'kefir'. It's very good.
I'm with you! Hummmmmm milk GOOD!
Well, I'm not sure I agree with the theory or not. But it could be one errant ancestor who passed their 'intolerant' genes to you. My grandparents were all immigrants. 3 from Eastern Europe and Russia, and the other further east, somewhere where Russia and Western Asia meet. My 3 blondish, fair siblings love milk. Drink it in huge quantities. Me, the 'dark' one, not only inherited my grandfather's severe allergies but I'm also lactose intolerant. We've long suspected that other aspects of the 'new world' diet have adversely affected the health of some family members, considering what was known about relatives abroad. I suspect my mother, while never officially diagnosed, was also lactose intolerant, based on her milk reactions. But the 'fermented' dairy products and those from sheep/goats - yogurt, kefir and some cheeses are my friends. Even acidophulus milk. For 'regular' cow dairy, I, too, cramp up and am miserable. I love pizza and ice cream, but pay for it.
I tried kefir once after reading in the Motley Fool about a micro-cap company in Chicago that makes it. My God, that stuff is horrible!
"It seems to me that a lot of the little young pup's just out of collage and/or in collage don't know __it, about the history of the world. People in Africa, not only drink cow's milk, but they drink camel's milk, goat milk, and mare's milk. And I guess they have been doing it for year's. So I guess you nailed it."
No college for me, but I did stay at a Holiday Inn Express last night.
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