1 May 2010

My inexpert foray into anthropology and genetics continues.

Okay, let me confess straight away: my post title is overdone. This isn’t about the first Cornishman. It is an occasional layman look at issues in our common human origin and at the contended evidence and theories about those origins and the subsequent human divisions. This is mired in difficulty. Knowledge and technology advance in anthropology, genetics, archeology, and history; and provisional truths rationally change in consequence. I am making the point that what we are unsure of and do not surely know about our origins is vast, much is uncertain, much is contended, and the first Cornishman is eternally elusive and unreachable but humans are remarkably genetically homogeneous. This latest post is prompted by two recent studies about events 2 million and 35 000 years ago. I have put below earlier posts about more recent events.

Australopithecus sediba

In 2008 two partial skeletons were found found in Malapa, southern Africa and dated from about two million years ago. Details were published last month in Science. One partial skeleton was of an adolescent male, one an adult female; and their place in the stew that is early humans is disputed. Questions abound. Do they represent a new species, Australopithecus sediba, a primate with both apelike and human characteristics? Should they be categorised as Australopithecus or Homo or are they, as claimed, transitional? Are they a descendant of Australopithecus africanus? Or are they a direct ancestor of our Homo genus and thus of you and me?

The human genus is reckoned to have arisen about two million years ago. Anatomically modern humans, homo sapiens sapiens, evolved much later of course and is the only surviving species from several. Behaviourally modern humans emerged about 50 000 years ago from a cultural explosion.

Here are a couple of interesting comments on the event

‘Close to Homo?’ in Laelaps blog of Brian Switek

‘Claim over “human ancestor” sparks furore’ in Nature 8 April 2010

The origins of modern Europeans: paleolithic, neolithic

Another study of European origins was published last month: ‘A comparison of Y chromosome variation in Sardinia and Anatolia is more consistent with cultural rather than demic diffusion of agriculture,’ Laura MORELLI et al, in PloS ONE 29 April 2010.

Put simply, the people of Europe are largely descended from paleolithic colonisers who arrived here around 35 000 years ago and from neolithic farmers, directly or indirectly from the Middle East, who began to move into Europe about 8 000 years ago. That much is agreed. The proportions of these two groups in the present European and British population is contended.

Linked to these ideas and also contended is the explanation of how agriculture came to Europe from its origins in the Middle East. There are two theories. First, it spread by cultural diffusion, without a significant migration of people into Europe, the original paleolithic hunter-gatherer inhabitants acculturating to the new farming ideas. Second, it spread by demic diffusion, by a significant migration into Europe by Middle Eastern farmers who brought their new farming ideas with them.

In addition to the Morelli study, here are two articles that discuss these various arguments and the balance of paleolithic and neolithic input

‘A predominantly neolithic origin for European paternal lineages,’ Patricia BALARESQUE et al, in PloS BiologyJanuary 2010.

‘Origins and evolution of the Europeans’ genome: evidence from multiple microsatellite loci,’ Elsie MS BELLE, in Proceedings of the Royal Society 7 July 2006.

This website is an excellent guide and portal into these tigerish waters:
Gene expression.

Additamentum 4 May 2010
This website offers an interesting discussion of the paleolithic/neolithic issue. See the post on it for 2 May 2010.

And here are my earlier posts which look at these issues in Cornwall

Cornwall 5460 years ago (The Balaresque study)

Blue eyed Cornish and English are brothers

English and Cornish are sisters under the skin

English and Cornish have the same milk gene

Ethnicity and Cornwall