Culture Shock May Explain Similarity Between Humans

ScienceNOW Daily News ^ | 8 January 2009 | Ann Gibbons

[neverdem]

Although humans come in many shapes and sizes, from the compact Inuit of the Arctic to the willowy Masai warriors of Africa, any two people are a lot more alike genetically than any pair of chimpanzees or gorillas. The reason may be our advanced culture, according to a new study. Our ancestors' different tools, eating habits, and even body decorations limited their mate choices to individuals of a similar culture, the work suggests, reducing the spread of new mutations across many groups. Because only a few of these ancient groups survived, humans are much less genetically diverse than other primates, even though there are many more of us on the planet. Ever since researchers discovered in the 1970s that humans lacked the genetic variation expected of our population size, they have proposed that our ancestors went through a big squeeze: Volcanic eruptions, disease, or climate change created a population "bottleneck" that reduced the number of breeding adults to about 10,000 sometime in the past 100,000 years. But new genetic studies of ancient DNA from Neandertals have found that they and the last ancestor they shared with humans, about 600,000 years ago, also lacked much genetic variation, which would require at least three dramatic bottlenecks--an improbable scenario. Meanwhile, other studies have found that language differences restricted gene flow in recent times in Europe, suggesting that cultural barriers might have limited genetic diversity more consistently than occasional local bottlenecks.

Paleoanthropologists Jean-Jacques Hublin and Luke Premo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, tested this hypothesis by simulating how mating preferences alter gene flow between individuals in different groups. Genetic variability plunged when individuals required mates with the highest degree of cultural similarity, the team reports this week in The Proceedings of the National Academy of Sciences. Conversely, genetic diversity increased when individuals were less selective about their mates--as is the case in chimpanzees or gorillas, which mate whenever possible with individuals from other groups.

Hublin and Premo propose that if human ancestors selected mates from similar backgrounds, there would have been a lot of inbreeding within different populations, restricting the flow of new mutations to other groups. "If these guys on the other side of the river spoke a different language and had different weapons, you would not try to mate with them or they might kill you," says Hublin. Over time, most populations went extinct, allowing the genes of only a few groups to proliferate, further erasing genetic diversity.

Researchers who have long worked on this problem are eager to test the new hypothesis in living hunter-gatherers. Paleoanthropologist John Hawks of the University of Wisconsin, Madison, for example, plans to ask his students to determine whether there's more intermarriage between hunter-gatherer groups that live close together and, therefore, are likely to have similar cultures. Biological anthropologist Henry Harpending of the University of Utah in Salt Lake City also likes the new explanation for the missing mutations: "It is time that human population geneticists recover from waving the magic wand of 'bottleneck' to try to explain everything."

[blam]

I know:

The Curse Of The Red-Headed Mummy

Tocharians

"Tocharian donors", possibly the "Knights with Long Swords" of Chinese accounts, depicted with light hair and light eye color and dressed in Sassanian style. 6th century CE fresco, Qizil, Tarim Basin. Graphical analysis reveals that the third donor from left is performing a Buddhist vitarka mudra. These frescoes are associated with annotations in Tocharian and Sanskrit made by their painters.There is evidence both from the mummies and Chinese writings that many of them had blonde or red hair and blue eyes, characteristics also found in present-day Afghanistan, Pakistan, Tajikistan and Central Asia, due to the populations' high genetic diversity. This suggests the possibility that they were part of an early migration of speakers of Indo-European languages that ended in what is now the Tarim Basin in western China. According to a controversial theory, early invasions by Turkic speakers may have pushed Tocharian speakers out of the Tarim Basin and into modern Afghanistan, India, Turkmenistan, Pakistan, Tajikistan, and Uzbekistan."

[neverdem]

bump for later

[SunkenCiv]

· join list or digest · view topics · view or post blog · bookmark · post a topic · subscribe ·
	Gods Graves Glyphs	Note: this topic is from January 10, 2009. Thanks neverdem. Although humans come in many shapes and sizes, from the compact Inuit of the Arctic to the willowy Masai warriors of Africa, any two people are a lot more alike genetically than any pair of chimpanzees or gorillas. To all -- please ping me to other topics which are appropriate for the GGG list. GGG managers are SunkenCiv, StayAt HomeMother, and Ernest_at_the_Beach
·Dogpile · Archaeologica · ArchaeoBlog · Archaeology · Biblical Archaeology Society · · Discover · Nat Geographic · Texas AM Anthro News · Yahoo Anthro & Archaeo · Google · · The Archaeology Channel · Excerpt, or Link only? · cgk's list of ping lists ·

[La Lydia]

Opposable thumbs help, too.

[668 - Neighbor of the Beast]

Ping for...I gotta think about this later.

[blam]

"It’s all fun and games until they found the blond guy in the Chinese graveyard."

"Somehow they never just get it right."

Here are the guys you're referring to. They don't change a thing regarding this article:

The Curse Of The Red-Headed Mummy

[blam]

Here is the cause of the last major genetic bottleneck for humans:

Late Pleostocene Human Population Bottlenecks. . . (Toba)

"The last glacial period was preceded by 1000 years of the coldest temperatures of the Late Pleistocene, apparently caused by the eruption of the Mount Toba volcano. The six year long volcanic winter and 1000-year-long instant Ice Age that followed Mount Toba's eruption may have decimated Modern Man's entire population. Genetic evidence suggests that Human population size fell to about 10,000 adults between 50 and 100 thousand years ago. The survivors from this global catastrophy would have found refuge in isolated tropical pockets, mainly in Equatorial Africa. Populations living in Europe and northern China would have been completely eliminated by the reduction of the summer temperatures by as much as 12 degrees centigrade. "

Some say the worldwide human population fell to as low as 2,000 humans worldwide. No-one says higher than 10,000 worldwide though.

[Miss Marple]

People don’t realize that Ice Ages come on very suddenly.

That’s why I pay attention to the current temperature trend. I am not looking forward to winter. Not at all.

[BenLurkin]

I thought the reason was that some catastrophy almost wiped out humanity — to the point that there were very few ancestors of the current population.

Or was that last years “scientific” theory?