Posted on 11/20/2004 6:42:15 AM PST by Lessismore
TORONTO, CANADA--More than 5000 experts met here from 26 to 30 October for the annual meeting of the American Society of Human Genetics. Longevity, milk digestion, and cancer were among the topics.
By some estimates, less than half of all adults can easily digest milk, a trait believed to have first appeared in people who kept dairy animals. Now scientists have traced the genetic roots of milk tolerance to the Ural mountains of western Russia, well north of where pastoralism is thought to have begun. The surprising result may support a theory that nomads from the Urals were one of two major farmer groups that spread into Europe, bringing the Indo-European languages that eventually diverged into the world's largest family of modern languages.
Almost all mammalian babies produce lactase, the enzyme that digests the milk sugar lactose. But in most animals and many people, the lactase gene is gradually turned off after infancy, leaving them unable to tolerate milk as adults. Two years ago, a team led by Leena Peltonen of the University of Helsinki, Finland, and the University of California, Los Angeles, identified mutations near the lactase gene that are associated with adult lactose tolerance and likely play a role in regulating the lactase gene. Now, Peltonen's team has tried to trace the origins of lactose tolerance by looking at 1611 DNA samples from 37 populations on four continents.
The populations having the greatest DNA sequence diversity around the lactase gene mutations--suggesting that lactose tolerance first appeared in them--include the Udmurts, Mokshas, Ezras, and other groups that originally lived between the Ural mountains and the Volga River. The trait most likely developed 4800 to 6600 years ago, Peltonen says. Her team linked the lactase gene changes to an ancestral variant that these groups apparently got from intermixing with tribes migrating from the Asian steppes.
After the Ural peoples gained this earlier form of the lactase gene, the lactose tolerance mutation "probably emerged by chance," says Peltonen, and then remained because it was beneficial for milk consumption. The Ural groups then likely later spread the variant to Europe--especially northern Europe, which has the highest lactose tolerance today--and the Middle East. The findings support the somewhat controversial theory that nomadic herders known as Kurgans expanded into Europe from the southern Urals 4500 to 3500 years ago, bringing Indo-European languages with them, according to Peltonen.
"I find [the new study] very interesting," says population geneticist Luigi Luca Cavalli-Sforza of Stanford University. He notes that a competing idea for explaining the origin of the Proto-Indo-Europeans is that they were crop-growing farmers from the Anatolia region in modern Turkey (Science, 27 February, p. 1323). But the milk study reinforces Cavalli-Sforza's view that both theories are correct: Indo-Europeans migrated to Europe in two waves, first from Turkey and later from the Urals.
Other geneticists caution that trying to pin down where a gene variant originated is tricky because the people in whom it's most common today may have migrated from somewhere else, or the original population could now be extinct. But if the milk gene's origin holds up, linguists and archaeologists will have new food for thought.
ping
Okay, who's Gene and why are the Ural farmers trying to milk him?
Were they led by some huge dude with black armor, deep voice, and never seemed to die?
Does this mean I can forget about the words of a psychiatrist, who told me, 30 years ago, that I couldn't digest milk after childhood because I had "issues" with my mother?
and - so? why? what? I am 53 and I STILL drink milk - all my cats up until they died at 18 & 20 drank milk - my dogs (pit bulls) like milk.
Is this just more PETA / ELF / ALF / ASPCA leftist gibberish in line with their agenda to make mankind the lesser species?
Good article, thanks. How did your intrests on Dauphin Island fare during the hurricane?
GGG Ping.
What on earth are you talking about? Did you actually read the article?
You did know there were billions of people that can't drink milk as adults, didn't you?
Please FREEPMAIL me if you want on, off, or alter the "Gods, Graves, Glyphs" PING list --
Archaeology/Anthropology/Ancient Cultures/Artifacts/Antiquities, etc.
The GGG Digest -- Gods, Graves, Glyphs (alpha order)
"Billions"? Hogwash.
Of COURSE they can drink milk. Milk costs good money and we're NOT pouring it down the drain. They can darn well sit there until they have finished their milk. And if they don't there'll be no dessert.
Gene Ping
I believe you. Our most over-rated profession.
Chinese and other Asians (Japanese, Vietnamese) can't drink milk. Black Africans can't drink milk. Native Americans can't drink milk.
Plenty of people of European ancestry can't drink milk, either. My husband can't, and neither can my younger son. My mother can't drink milk, but my father can.
My older son and I both love milk. Between us we drink about two gallons a week. Not to mention yogurt, ice cream and cheese, which are more digestible for the lactose intolerant.
Thanks for the ping. It's interesting, but this looks like routine genetics, so I suspect it won't get the evolution crowd very worked up.
BTTT
Sob...I still remember missing recess, sitting in the cafeteria, because I refused to drink my milk! I knew if I drank it, there would be a mess to clean up later. I have the strongest bones in the world...and I never drank milk!
The ability to feed infants cow's milk, mare's milk, goat's milk or sheep's milk after their mother died or was too ill to produce milk must have contributed to the spread of the lactose tolerance gene.
I recall at least one infant burial among the Xinjiang Caucasian mummies where a leather "baby bottle" made out of (if I recall correctly) a goat's nipple was buried with the child.
Actually, this might explain, in part, why Causasians are so much taller than Asians and most Africans -- milk in the diet makes strong bones. The Masai, who are extremely tall Africans, also drink milk.
So, I think this is pertinent to evolution.
My impression is that for most creationists, there are two things about evolutionary theor that upsets them - first, they object to the theory that life appeared out of nowhere ("cosmic soup"), which really has nothing to do with evolutionary theory per se, and they object to the theory that evolution is the result solely of random events, which really has little to do with evolutionary theory, either.
I posit that if these concepts were not taught as part of evolution, the ruckus would die down. JMHO.
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