Skip to comments.Study Detects Recent Instance of Human Evolution
Posted on 12/10/2006 2:44:11 PM PST by Alter Kaker
A surprisingly recent instance of human evolution has been detected among the peoples of East Africa. It is the ability to digest milk in adulthood, conferred by genetic changes that occurred as recently as 3,000 years ago, a team of geneticists has found.
The finding is a striking example of a cultural practice the raising of dairy cattle feeding back into the human genome. It also seems to be one of the first instances of convergent human evolution to be documented at the genetic level. Convergent evolution refers to two or more populations acquiring the same trait independently.
Throughout most of human history, the ability to digest lactose, the principal sugar of milk, has been switched off after weaning because there is no further need for the lactase enzyme that breaks the sugar apart. But when cattle were first domesticated 9,000 years ago and people later started to consume their milk as well as their meat, natural selection would have favored anyone with a mutation that kept the lactase gene switched on.
Such a mutation is known to have arisen among an early cattle-raising people, the Funnel Beaker culture, which flourished some 5,000 to 6,000 years ago in north-central Europe. People with a persistently active lactase gene have no problem digesting milk and are said to be lactose tolerant.
(Excerpt) Read more at nytimes.com ...
I miss funny tv of the 60's, I watched tv shows then, and I laughed bigtime...thank God, Freepers are so funny I can get my laughs here. All of you are so clever, good for you!
Bottom line re species: a cat will never be a turtle...a lizard will never be a zebra. God said ...each to it's own kind. That will never be broken.
"They believed it was caused by the cow eating some type of plant and contaminating the milk."
Wasn't it Jimsonweed?
From my own experience, I can't say that I've ever seen cattle eat jimson weed. Simply handling the stuff leaves a smell that is hard to remove. It wouldn't seem to be very tasty. But who knows what an animal stressed with hunger might eat.
I don't believe anybody's ever claimed cats turn into birds or lizards turn into zebras. But please, don't keep you from reveling in your ignorance.
Why would 'natural selection' favor someone who could drink milk?
And for the anthropologists, et al. Gotta keep those grants coming. . .gotta toe the party line. ;)
There is a significant amount of genetic variation between different etnic groups of humans. Blonde hair and blue eyes were and are a favorable mutation for northern European populations. Why? The paler complexion is more favorable to the absorption of UV light, needed for Vitamin D production.
However, for populations living in tropical regions, a dark skin is a favorable genetic variation. Why? For protection against much higher levels of UV light.
When the gene for sicle cell anemia is heterozygous, the gene offers some protection against malaria. However, when the individual is homozygous for the trait, the person develops sicle cell anemia, a potentially fatal disease.
In general, populations from Northern Europe, cary the gene variation for digesting lactose. The European populations had a greater need for milk, to supply the needed nutrients for producting vitamin D. However, populations from tropical regions had less need for the ability to consume milk, because they receive a lot more sunlight.
Did a quick search, and it wasn't Jimsonweed, it was White Snakeroot. Abraham Lincoln's mother died from milk tainted with it. Sounds like laws were passed about fencing cattle in as a result, since they got into it running free range, it grew in forested areas.
Thanks for the info!
It's brought us here...
Recombinant DNA technology will shortly produce an animal that looks like a cat on the outside but tastes like chicken on the inside.
Because it's a food source. People who couldn't drink milk had less food to subsist on and were less likely to survive.
Although we've come up with the term "cheese eating surrender monkey", it's actually the case that those who can eat fresh cheese will probably outlive those who can't.
(NOTE: aged cheese has little if any lactose).
Cows have a Northernmost limit. The gene for lactose metabolism would have limited benefit to people living North of that limit. Instead, they developed an immense appetite for fish and seamammals.
I would think the casualty rate would be kinda high if milk consumption was attempted before domestication.
The Sa'ami domesticated reindeer in the 1700s. However, they'd been milking them for thousands of years.
Abraham Lincoln's mother supposedly died of "milk sick." I wondered later if it were salmonella.
Sigh. Is it also evolution when farmers select out sheep for their capacity to "twin" and double his production? It sure didn't take 3K years to manage that...
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