Posted on 12/11/2006 12:43:08 PM PST by neverdem
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 the lactase enzyme that breaks the sugar apart is no longer needed. 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 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.
Almost all Dutch people and 99 percent of Swedes are lactose tolerant, but the mutation becomes progressively less common in Europeans who live at increasing distances from the ancient Funnel Beaker region.
Geneticists wondered if the lactose tolerance mutation in Europeans, identified in 2002, had arisen among pastoral peoples elsewhere. But it seemed to be largely absent from Africa, even though pastoral peoples there generally have some degree of tolerance.
A research team led by Dr. Sarah Tishkoff of the University of...
(Excerpt) Read more at nytimes.com ...
A SNP in the gene encoding lactase (LCT) (C/T-13910) is associated with the ability to digest milk as adults (lactase persistence) in Europeans, but the genetic basis of lactase persistence in Africans was previously unknown. We conducted a genotype-phenotype association study in 470 Tanzanians, Kenyans and Sudanese and identified three SNPs (G/C-14010, T/G-13915 and C/G-13907) that are associated with lactase persistence and that have derived alleles that significantly enhance transcription from the LCT promoter in vitro. These SNPs originated on different haplotype backgrounds from the European C/T-13910 SNP and from each other. Genotyping across a 3-Mb region demonstrated haplotype homozygosity extending >2.0 Mb on chromosomes carrying C-14010, consistent with a selective sweep over the past 7,000 years. These data provide a marked example of convergent evolution due to strong selective pressure resulting from shared cultural traits—animal domestication and adult milk consumption.
However, if I drink pasteurized milk or eat cheese made with pasteurized milk, I get very, very sick. I wonder if many people who are diagnosed with lactose intolerance are actually intolerant of over-pasteurization.
There is lots of Chinese and African food I simply cannot eat either.
Monkey
Bird eyes
Being cultural does not make it evolutionary.
WOW!
I'm curious whether you're getting the raw milk from the same cows as you get the pasteurized milk. What type of cows...Holsteins? Have you compared Jersey with Holsteins? How about Guernseys or others?
Duplicate: Another day AlterKaker posted the same article [NYT source, Nicholas Wade author]: http://www.freerepublic.com/focus/f-news/1751427/posts
Based on the piece and your description of your status, you are possibly "mid-mutation". I'd get that checked out. It could be a "missing link" thing. (just kidding).
lol Macro- evolution is an introduction of NEW information- NOT molding information already present in a species- but I guess that would have been too negative a point in support for their "There aint no God' theory. http://sacredscoop.com
They change titles and seem to run the same Nicholas Wade stories on following days recently. IIRC, they did it with resveratrol, that ingredient found in wine that seems to effect sirtuin? genes.
My line must have split away from East Africa before the domestication of cattle - give me anything but Lactaid and well, it is not unlike a certain scene from Blazing Saddles ....
Lactose Intolerance - FRINK!
I believe the article incorrectly refers to this as evolution when it is in fact, adaptation through genetic predisposition.
In other words, the genes for lactose tolerance did not just suddenly appear, they existed all along and the population of lactose tolerant people is just shifting in percentage.
Utter nonsense. In order for it to be evolution, one must trace the people with lactose tolerance back to a specific ancestor with a random mutation, and show how this gene was passed on to descendants who out-survived and out-reproduced their peers.
I can't answer that question but I'm convinced that pasteurization destroys something in the milk (lactase or some other enzyme)which would make it digestible.
Natural selection occurred when the lactose intolerants kept farting, thus driving away potential mates
ROFL~!
*(by "scientists" desperate to prove evolution by emperical, other than fantasy evidence such as grasping at straws such as dazzling the scientific community with forensic enzyme data which has no real context )
I think you meant to say "UDDER non-sense" !
Pasteurization kills any bacteria in the milk, which is good if you're concerned about avoiding nasty stuff like salmonella.
You may find that you'd be able to handle pasteurized milk that's had acidophilus cultures added.
If only I had asked my wife the simple question... Are you lactose intolerant? My life might have been different...
Fortunately, they make pretty good whole house fans, so its not like a totally unacceptable situation. :)
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