Saturday, September 22, 2012

Namakw Nomadic Dome(s)tic

A possible tie-in
kusa/kosa/kosei cf khoi-khoi-san of namakwa/kalahari SW Africa
 "noma/nomatka/nomatzinco(Nauatl)=forever" cf namakwa/nomadic/dome(s)tic

The Khoe-San people of southern Africa, who speak a language based on

clicking sounds, are descendants of the most ancient genetic split

found yet in living humans, finds an international group of


The results also reveal some of the evolutionary changes that helped

give rise to modern humanity.

Anatomically modern humans (us), evolved about 200,000 years ago in

Africa. Differences between people living today and our evolutionary

relatives include much less pronounced eyebrow ridges and larger


Much remains uncertain about how modern humans originated in Africa's

cradle of humanity. For instance, researchers had long thought humans

arose in eastern Africa, but recent studies hint at roots in southern

Africa. [Image Gallery: Our Closest Human Ancestor]

Khoe-San genes

To help uncover the origins of humanity, scientists analyzed genetic

variations across 220 individuals from 11 different populations in

southern Africa to explore their relationships and commonalities.

Approximately 2.3 million DNA variations were analyzed per person.

The investigators found the earliest diversification event in the

history of all humans occurred about 100,000 years ago. That is well

before modern humans migrated out of Africa and about twice as old as

the divergences of central African Pygmies and East African

hunter-gatherers and from other African groups, said researcher Carina

Schlebusch at Uppsala University in Sweden.

The descendants of this split are the Khoe-San people, the two

hunter-gatherer ethnic groups who are known for speaking with clicks

and share many other traits. Historically, the Khoe were pastoralists,

employing domesticated sheep and cattle, while the San were


It remains uncertain what exactly made the Khoe-San diverge and become

genetically isolated from other African groups.Still, "the African

continent is large, and there are geographic barriers to gene

flow,"researcher Mattias Jakobsson, also of Uppsala University, told


"Another factor that might play a role in the isolation of African

populations is also the cycling of the ice ages," Schlebusch told

LiveScience."In Africa, you get stages of really arid conditions with

ice ages and we see population contractions."

The scientists aren't sure the purposes of the genetic variations that

set the Khoe-San apart. The extent to which each gene variation shapes

what people are like physically "is very, very hard to understand at

this stage," researcher Himla Soodyall at the University of the

Witwatersrand in South Africa told LiveScience.

Rise of modern humans

The researchers also identified genetic variations that emerged before

this split between the Khoe-San and other groups, adaptations linked

to the rise of modern humans as a whole. These appear linked with

skeletal development, such as bone and cartilage growth, as well as

immune system and brain cell function.

"There's one gene where if you have mutations in that gene, you get

heavy eyebrow ridges and rib cages that look like something that could

potentially be Neanderthal or archaic human," Jakobsson told

LiveScience. This finding suggests that further analysis of these

African groups "will help us understand the emergence of anatomically

modern humans."

Instead of pinpointing a single location from which modern humans

arose, the genetic analysis revealed "different parts of Africa show

up as potentially being the origin of anatomically modern humans,"

Jakobsson said. That suggests many different groups contributed to the

gene pool "that then later on became anatomically modern humans," he


The research also yielded insights on how pastoralism first spread to

southern Africa. Among the Nama, a pastoralist Khoe group, the

scientists found a small but very distinct genetic component that is

shared with east Africans — for instance, the cattle-herding Maasai.

"We postulate that this east African component was introduced by east

African groups that brought pastoralist practices to southern Africa,"

Schlebusch said.

In addition, the northern San populations differed from the southern

San in terms of their immune systems. "We know the southern San

populations had more contact with Bantu-speaking individuals and also

incoming colonists that colonized South Africa in the 1600s, so it

might be that the southern San populations were exposed to more novel

diseases than northern San populations which were more isolated,"

Schlebusch said.

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