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skywizard
28th January 2014, 01:04
Hunter-gatherer roots, Paleo diet and some possible traces of African genes

http://l.yimg.com/bt/api/res/1.2/8gUWykJ2VEMJ5lxJtkSf7Q--/YXBwaWQ9eW5ld3M7Zmk9ZmlsbDtoPTgwNztweW9mZj0wO3E9Nz U7dz03MzA-/http://l.yimg.com/os/publish-images/news/2014-01-27/6b1b5acf-f088-4864-af01-ffaa0837f1c2_ancient-man2.jpg
A 7,000-year-old man from the Mesolithic Period had blue eyes and dark skin.


Dark skin. Blue eyes. Beard. Thin and borderline lactose-intolerant. (wonder if that caused problems as a new born when breast feeding?) :scrhd:

That's what scientists say man may have looked like 7,000 years ago, after studying DNA from bones discovered in a Spanish cave. The Mesolithic skeleton found at the La Brana-Arintero site in Leon in 2006 is thought to be the first recovered genome of a European from that period.

According to a study published on Sunday in the journal Nature, pigmentation genes extracted from a tooth of the man — dubbed La Brana 1 — reveal he had dark skin like an African-American but the blue eyes of a Scandanavian, "suggesting the light skin of modern Europeans was not yet ubiquitous in Mesolithic times."

"The biggest surprise was to discover that this individual possessed African versions in the genes that determine the light pigmentation of the current Europeans," Carles Lalueza-Fox, a researcher from the Spanish National Research Council, said in a press release accompanying the findings.

While the man had dark skin, Lalueza-Fox said, "we cannot know the exact shade."

La Brana 1 was a hunter-gatherer subsisting on a low-starch diet and had trouble digesting milk.

"The arrival of the Neolithic, with a carbohydrate-based diet and new pathogens transmitted by domesticated animals, entailed metabolic and immunological challenges that were reflected in genetic adaptations of post-Mesolithic populations," the study noted. "Among these is the ability to digest lactose, which La Brana individual could not do."

But the 7,000-year-old also had an advanced immune system normally associated with modern Europeans, the study found.

The researchers added that more genome analysis is necessary from the Mesolithic Period to determine whether La Brana 1's looks were common. The group is preparing to study the remains of "La Brana 2," another male found in the same cave.


Source: http://news.yahoo.com/what-humans-may-have-looked-like-7-000-years-ago-153941503.html


peace...
skywizard

Seikou-Kishi
28th January 2014, 02:50
High Skywizard. When it comes to the idea of lactose intolerance and problems breastfeeding, I think I can answer that. Like most mammalian species, humans were originally lactose intolerant as adults, but not as children. Milk originated as a way of giving nutrition to a baby about the time mammals stopped laying eggs. Eggs contain all the nourishment a fertilised cell needs to develop as a foetus into a fully-functional baby.

When mammals first started to diversify under the dinosaurs, they were often unable to afford the single, huge, one-off instalment of nourishment that an egg required (once the shell was finished and the egg laid, nothing further could be given to it). To meet this precariousness of resources, mammals developed two different mechanisms. Both groups made more sophisticated the "egg processing machinery" of the female reprodutive organs. (This accounts for the huge size difference between the male and female sex hormones; creating sperm is relatively simple compared to everything involved in pregnancy and breast-feeding.) Marsupial mammals ejected foetuses quickly from their wombs and the foetuses clung to their bodies and they eventually developed pouches. Placental mammals, like humans, developed yet more sophisticated wombs that enabled much greater foetal development before the foetus had to be ejected.

In both cases, the genes which produced yolk for eggs began to switch off and were replaced with genes that cause mammals to produce milk. Even modern egg-laying mammals (the monotremes) have progressed somewhat down this route, deactivating one or two yolk-producing genes in favour of some of the three milk-producing genes. They have fewer yolk genes than reptiles and consequently their eggs are smaller, with less yolk. This is supplemented with a little milk (not as much as marsupial or placental mammals). Unlike marsupials, they lack nipples and unlike placentals they lack the complex milk-production and storage capabilities that are breasts.

Anyway, because milk originated as a yolk substitute intended to allow mammals to nourish their young with a smaller but continual supply, it was intended only for the consumption of babies (in the case of placentals and monotremes) and babies and foetuses (in the case of marsupials). Because of this, once the baby reached weening age, the genes for the creation of lactase (the enzyme that digests lactose, a milk sugar) began to switch off. They did this because creating enzymes for a substance that was no longer consumed was an inefficient use of resources in animals that weren't at the tops of their food chains and so couldn't afford frivolous expenditure.

As some humans began to use the milk of domesticated animals later and later, becoming a lifelong staple, those genes which coded for lactase began not to get switched off (again) as the lactase was still in use. Most European phenotypes had the adaptation for lifelong lactase production (because in harsh, European winters, milk was sometimes the only sustainable source of nourishment) while many African phenotypes did not (notable exceptions include the Masai). Lactose intolerance in human adults is usually a result of the reexpression of this ancient cut-off point, and many people who are lactose intolerant as adults often weren't as babies. The rise of lactose intolerant babies is a new phenomenon, probably caused by hormone-mimicking pollutants ubiquitous in modern water drunk by both pregnant and breast-feeding mothers and also by young children in "formula".

If these ancient humans were lactose intolerant (and they probably were), the children probably were not. Milk began its existence as specialised baby food, and so babies could digest it even where adults could not. It all has to do with how mammals first started producing milk, why, and in what circumstances. It's also the reason women's breasts only start to produce milk during pregnancy; biologically and evolutionarily, a creature will not willingly give up all the nutrition in milk except insofar as it nourishes their offspring.

Hope this helps.