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 ...
If it's 3000 years ago, why does the Bible describe Canaan as a "land flowing with milk and honey"? Doesn't that quotation predate 1000 BC?
Hey mister, how is the cow???
Selective breeding is evolution, but it isn't Darwinian evolution, because the selection is artificial and isn't natural.
What what?
The milk in the Bible is goat's milk, which is much easier to digest than cow's milk.
Most interesting.
Of course, there will be a few detours. Like an animal that looks like a chicken on the outside but tastes like cat on the inside.
OK, just one question: Why did our ancestors bother to domesticate milk cows, when they couldn't digest the milk in the first place? Did they know that some day, they would become lactose tolerant? If this is evolution, wouldn't that mean our ancestors had to be drinking milk, as adults, for a long time, in the hope that some day their children, or grandchildren, etc, would mutate that gene? Wow, our ancestors were VERY forward thinking.
"I don't believe anybody's ever claimed cats turn into birds or lizards turn into zebras."
No, nothing that crazy, they just claim that prokaryotes turned into humans. You're right to point out how delusional any poster is if they joke about how lizards turned into zebras. Clearly, it was dinosaurs that turned into zebras. There, now we've straightened out that problem.
Human tastes are not necessarily shared by animals. For instance, goats like the taste of poison ivy.
I guess that's why they can't duplicate Darwinism in the lab--cause that wouldn't be natch'rl.
1. Presumably they didn't originally domesticate cattle for milk, they domesticated them for meat.
2. As has already been noted, early humans could digest milk products, just not raw milk -- cheese and butter and fermented milk (tastes nasty but will keep you alive) were always edible.
And it only took 3.5 billion years, too. Nobody pretends that a prokaryote will grow two arms and two legs over night and graduate from the Harvard Law School. Your incredulousness stems from a poverty of vision on your part, not from any problem with evolutionary theory.
OK, lessee if I've got this right: humans, who already had domesticated cattle for meat, cheese, butter and fermented milk, selected a gene that would allow them to digest whole cow milk, in order to have better nutrition, by being around milk. Not drinking it after a certain age, just by being around it. And this tolerance for that dairy product, unlike those other dairy products, made them candidates for survival, while those who... didn't stand close enough to the whole milk... died before reproducing. It makes perfect sense. Those creationist idiots will probably make fun of that logic.
No, natural selection isn't random variation. You're confusing mutation (which sometimes occurs because of random variation) with natural selection, which is something altogether different.
would not favor anyone it selects, and how would it know to select milk drinkers.
On the contrary, if milk drinkers were better nourished than their non-milk drinking neighbors, then they would be more likely to survive to reproductive maturity and natural selection would certainly favor them.
Natural selection is a random act that brings everything back to the average.
You got it backwards. Better genes tend to survive. If someone has mutated genes that increase their chances of survival over the average, natural selection will favor them.
how would it know to select milk drinkers
It doesn't. People who are better nourished are more likely to survive. People who can drink milk are more likely to be well nourished. That's natural selection.
. But the 3000 year thing is close to Biblical flood time of around 4500 years when God told man to eat meat.
Did you read the article? There were at least two independent mutations. One that allowed East Africans to drink milk, about 3000 years ago. An earlier mutation allowed Northern Europeans to drink milk, 6000 years ago. You are really a one-track record --- you'll read your creation myth into anything. If you were a contestant on Jeopardy, I suspect every answer would be "What is the Noahic flood."
"Your incredulousness stems from a poverty of vision on your part, not from any problem with evolutionary theory."
Yep, it's my own inability to accept the impossible that makes me so stubborn. It couldn't be that evolution can never answer the big questions, like how did life form from inanimate matter? I'll tell you what. You get all your PhD's together, gather up all the water, oxygen, nutrients, and anything else you want, all of it inanimate, and make a single-celled form of life, then give me a call.
It's very easy to spot evidence of recent human evolution. Some humans evolved...the rest remained democrats.
Humans didn't do anything. A mutation just happened in an individual, and the offspring of that individual were able to receive better nutrition than the offspring of other individuals without the mutation.
Standing close to whole milk didn't do anything -- the mutation would have occured in any event. However, in a culture without cattle, the mutation would have not been beneficial and would have conferred no benefit on individuals with the mutated gene. In that circumstance, the gene would have probably disappeared. Selection is what favors a particular random mutation within a given environemnt.
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