Forum > Anthropology

Neanderthal Walks With Us

(1/1)

𝕽𝖊𝖛.𝕮𝖆𝖒𝖇𝖊𝖚𝖑:
Neanderthal lives in us all

By Cheryl Jones

http://www.theaustralian.com.au/higher-education/neanderthal-lives-in-us-all/story-e6frgcjx-1225865188007

IT was expected to be a ruling on rival models of human evolution, written in a code of billions of letters. But an analysis of the draft Neanderthal genome sequence, published last week, has widened the dispute over our ancestry.

Opposing camps are claiming support for their theories in the celebrated cavemen's DNA.

Attention is returning to Australian Aborigines and fossils of Indonesian Home erectus for evidence to settle the long-running dispute over human origins and dispersal.

The scientific community was stunned last week when an international team led by the Max Planck Institute in Leipzig published results in Science of its analysis of a sequence covering 60 per cent of the Neanderthal genome.

The work showed that the Neanderthals, who reigned over Europe and the Middle East for more than 100,000 years, contributed between 1 per cent and 4 per cent of the DNA of present-day people outside Africa.

"The Neanderthals are not totally extinct," Max Planck Institute geneticist Svante Paabo told journalists in a teleconference. "In some of us, they live on a little bit."

Since the Neanderthal type specimen (the material on which the formal species definition is based) was discovered at Feldhofer in Germany's Neander Valley in 1856, scholars have been arguing about the status of the stocky hominin.

The debate over Homo neanderthalensis has been politically charged. Some Neanderthal advocates view the hominins, which had protruding brow ridges, big noses and, in some cases, red hair, more as a former ethnic minority of modern humans than as members of a different, extinct species.

The Neanderthals had passable stone technology. They decorated their bodies and probably had some level of language. Some scholars say they buried their dead and cared for their sick and elderly. But, until now, many have doubted that the hominins would have stirred romantic passions in our species.

The place of Neanderthals in the human family tree is critical to two competing models of human evolution. According to the multi-regionalist model, modern humans, or Homo sapiens, evolved in several places, with interbreeding pushing a single species down the same evolutionary pathway. Modern populations retained regional characteristics. According to that theory, the Neanderthals are the ancestors of modern Europeans and other Caucasian people, while Homo erectus populations in Indonesia are the progenitors of the Aborigines. [See Erectus Walks Amongst Us]

The extreme form of the rival "out of Africa" model argues for the evolution of Homo sapiens in Africa up to 200,000 years ago. Our ancestors spread across the globe, replacing the descendants of archaic species who left Africa more than a million years ago.

The Neanderthals, who had evolved from Homo heidelbergensis in Europe, were among the casualties. Neanderthals went extinct, perhaps within 10,000 years of the arrival of Homo sapiens on their territory. Multi-regionalism was once the dominant paradigm but the out of Africa model is now ascendant. In recent years, some scholars have adopted an assimilation model that accommodates limited interbreeding between African newcomers and the locals.

The debate first centred on the fossil record, with scholars arguing over the interpretation of specimens claimed by multi-regionalists to be Neanderthal-sapiens intermediates.

In the late 1980s genetics began to have an effect. The first genetics research supported the out of Africa model, but most of the work centred on the maternally inherited DNA from the mitochondria, structures outside cell nuclei that power cells.

Mitochondrial DNA accounts for just a tiny fraction of our DNA, so it does not tell the full story. And much of the first evolutionary genetics research was on present-day human DNA.

Regions of the Neanderthal mitochondrial genome were sequenced in the 1990s. Eventually, the hominins' full mitochondrial genome was sequenced, but the results found no evidence for Neanderthal DNA in the modern human gene pool.

Technological advances, including high-throughput sequencers and new ways to deal with old, degraded DNA, cleared the way to sequencing the entire Neanderthal nuclear genome, a code written in six billion letters. DNA from cell nuclei codes for most traits.

The ambitious Neanderthal Genome Project was launched in 2006 to resolve the row over human origins.

The team extracted DNA from Neanderthal bones from Vindija Cave in northern Croatia. One specimen was about 43,300 years old, with a second dated to about 47,600 years old. The date of the third bone fragment is even older but it is not known by how much.

The scientists compared Neanderthal DNA with that of the modern chimpanzee and five present-day modern humans: one from Papua New Guinea, two from Africa, one from China and one from France. [The Frenchy was probably a Moroccan quadroon with a turban on its head and a Koran in its pocket ~ Cailen.]

They were surprised to find evidence of "gene flow" from Neanderthals to present-day humans outside Africa. All the non-African populations had the same amount of Neanderthal blood. The simplest explanation, the team argues, is that the encounters happened before the non-African modern human populations diverged and at the gateway, perhaps in the Middle East, through which our species passed as it left the African homeland.

Estimates put the date of the exodus between 50,000 and 70,000 years ago, with modern humans reaching Australia at least 50,000 years ago and Europe about 40,000 years ago.

Neanderthal Genome Project team member David Reich, a population geneticist at Harvard University medical school, says the data refutes "the strong view" of the out of Africa model in which there was "absolutely no mixture" between Neanderthals and the African migrants.

"But the overall view of the out of Africa migration is strongly supported by our data," he says.

The "great majority" of the ancestry of populations outside Africa today is from Africa.

"There's only a small percentage that seems to come from this other, Neanderthal-related source."

However, it is unclear how much interbreeding it would take to scuttle the Africanist model.

Meanwhile, the failure of the analysis to pick up a stronger signal in the European [or perhaps quadroon ~ Cailen] Homo sapiens sampled than in the other non-Africans seemingly weakens the multi-regionalist case.

However, the lead author of the Science paper, Richard Green, now of the University of California, Santa Cruz, says that the team could not rule out "a smaller and later contribution just in Europe".

Leading multiregionalist theorist Milford Wolpoff, of the University of Michigan, says his model has been misrepresented in the past.

"In our original statement, we said that most evolution until the Late Pleistocene was at the centre - Africa - with genes under selection dispersing outwards," he says.

"The difference between us and the African replacement theory is not over Africa. It is over replacement.

"Either there was a speciation or there was not, and the Neanderthal genetic evidence joins anatomical evidence to show there was not.

"It's that simple, but politics has not gone away, and now lots of folks are claiming that they never denied intermixture. That's politics, not science.

"The fact is that no form of species replacement can be correct now, and evolution within a species, without speciation, is called multi-regional evolution."

Leading out of Africa theorist Colin Groves, a primatologist at the Australian National University, disputes Wolpoff's reading of the European fossil record.

The Neanderthal genome work is continuing, but Groves thinks the last word in the wider debate may come from Australia. He and Flinders University palaeoanthropologist Michael Westaway last year published results from the biggest anatomical study of fossil skulls from Australia, Indonesia Africa and the Middle East.

The research, led by Westaway and published in Archaeology in Oceania, supported the out of Africa theory, finding no evidence in the ancestral Australians of characteristics inherited from Indonesian Homo erectus. "The anatomical features of Homo sapiens are sharply distinct from those of the populations it displaced outside Africa," Groves says.

Cheryl Jones is a science journalist and co-author of The Bone Readers: Atoms, Genes and the Politics of Australia's Deep Past, published by Allen & Unwin. http://www.allenandunwin.com/_uploads/BookPdf/Extract/9781741147285.pdf

ScottHarrison:
The Out of Africa theory has been a lot like a barking dog with no bite for many years now, it just doesn't stand up to serious scrutiny. The egalitarian mob has been pushing the "we're all African" rot for years, much the same as the fallacy that "race is a social construct."

Ronald Alan Fonda and Richard D. Fuerle have written extensively on the multi-regional theory, that shoots the Out of Africa theory down in flames. I encourage all Creators to take a look at their material.

All the evidence points toward race being a legitimate biological concept and that the White race is at the height of human evolution.

Br.MarkCook:
Great article  PM ! 

𝕽𝖊𝖛.𝕮𝖆𝖒𝖇𝖊𝖚𝖑:
Modern Humanity Evolved in Europe

Navigation

[0] Message Index

Go to full version