25 September 2010

Selected New Discoveries In Anthropology

Dienekes has conveniently posted some of the interesting abstracts from the 4th International Symposium on Biomolecular Archaeology. A few of the interesting results are summarized below.

Old World Research

* The first farming culture in Central Europe arrived there around 7,000 to 7,500 years ago and is known as the Linearbandkeramik aka LBK aka Linear Pottery culture. Researchers examined "mitochondrial and Y-chromosomal data from Neolithic individuals from a Central European early farming site, Derenburg (Germany)." This ancient DNA shows that the earliest farmers had a genetic affinity to modern Near Eastern populations (where farming was first invented), rather than to modern humans that first arrived there in the Upper Paleolithic (i.e. 40,000 years ago) and had a hunter-gatherer economy.

This suggests that the transition from hunting and gathering to farming in modern humans largely involved population replacement, rather than cultural transfer of farming technology.

A theory in which population replacement is predominant, also known as migrationism, would also help explain why Europeans all have roughly the same percentage of Neanderthal DNA, despite the fact that we would expect Upper Paleolithic in Northern Europe to have more Neanderthal DNA than Near Eastern modern humans. We would expect Upper Paleolithic modern humans in Northern Europe to have more Neanderthal DNA because successive generations of Upper Paleolithic modern humans would have had many more generations in which they would have been in close proximity to Neanderthals.

If the Upper Paleolithic modern humans made only small genetic contributions to the current population of Europe, then any Neanderthal admixture that left traces in that population would have been diluted to the point where it would be almost unrecognizable. Near Eastern farmers and herders who replaced Upper Paleolithic modern humans in Europe would have only traced of the admixture that took place in the Near East. By the time they arrived in Europe, Neanderthals had been extinct for tens of thousands of years.

Migrationism also helps explain why there is so very little genetic variation between European populations compared to other parts of the world. Even though modern humans have lived in Europe for 40,000 years, the bulk of their genetic ancestry may derive from a common Near Eastern farming and herding population in the last 10,000 years.

The only traits that would have survived migration and gone on to be present at high frequencie in contemporary European populations would have been those that entered the gene pool from the small amount of introgression of genes into the early farmer gene pool from earlier modern human populations that did take place, which either conferred very strong selective advantages or were part of some lineage that left an unusually large number of descendants for some other reason (e.g. an early marriage alliance into the aristocracy of the early farming population).

* Analysis of ancient pig DNA provides insights into the early migrations of farmers into Europe, and the genetic origins of ancient pigs. This too supports a migrationist analysis:

The Neolithisation of Europe followed two main routes of expansion – the northern so called Danubian or Balkanic route and the southern Mediterranean route. . . . [T]he earliest domestic pigs in Europe were of Near Eastern descent. . . Our results support the current hypothesis that divergent mitochondrial lineages accompanied the different routes of expansion. . . . [But] by 4000 BC, introgression with wild boar was widespread in Europe.

Another study also looked at pig origins, and gives it a subtly different interpretation:

The results of over 300 individuals from 25 neolithic sites shows that around 4800- 4000 BC domestic pigs are introduced in the archaeological sites in northern Germany. . . the oldest domestic pig in the sample (4600 BC) has a “Near East” haplotype. All other domestic and wild boars show the same “European” haplotype. . . . the domestic pigs with a maternal “Near East” ancestor were introduced into central Europe with the linear pottery (LBK) culture. After a short period the domestic pigs with “European” haplotypes coexist with the “Near East” haplotypes in the LBK and the Chaseen culture. An explanation could be that the people of the Ertebølle culture adapt the idea of domestication and permuted it on the indigenous wild boar population.

Ancient pig DNA also matters because it provides a relatively independent and scientifically rigorous line of evidence coroborating the picture of human migrations into Europe in pre-history that has already been developed by other means.

Taken alone, some of the conclusions reached might be expansive, but when they reinforce conclusions already reached on the basis of modern and ancient human DNA, and on the basis of artifacts discovered in archeological digs and carbon dated, they make the evidence in support of the developing anthropological reconstruction of human pre-history in Europe considerably more robust. This research helps to insulate the overall conclusion that have been reached about the spread of farming in the early Neolithic era in Europe from any specific methological flaw that might make any one line of evidence less definitive than it had previously seemed.

* Analysis of the traces of materials that were stored in Beaker pottery, a post-Neolithic revolution culture, that is found in British graves show that, contrary to widespread supposition about the purposes for which they were used, that they were not used to hold alcohol.

New World Research

* A complete genome was obtained from a 4,000 year old piece of permafrost preserved hair of a man from the first known culture to settle in Greenland.

Analyses provide evidence of a migration from Siberia into the New World, independent of that giving rise to the modern Native Americans and Inuit. The migration was dated to approximately 5,500 years BP and the closest living relatives are found in North-East Siberia showing no signs of admixture with modern Native Americans or Inuit.

* Ancient DNA evidence is helping to determine: "To what extent are the early and late prehistoric Southwest occupants associated with the Mesa Verde, Chaco Canyon, Mimbres and Basketmaker cultures related to today’s Athapaskan, Puebloan and Uto-Aztecan speakers?" It can also help determine where these people's origins were in the Americas. Early examination of ancient DNA evidence in this region "has demonstrated both regional continuity and discontinuity." The abstract doesn't make clear, however, what conclusions this data has revealed, or the broad outline of the kinds of continuity and discontinuity that the earlier findings revealed.

* "DNA . . . extracted from over 115 samples exhibiting classic tuberculosis lesions obtained from both the New and Old Worlds and ranging in age from 5800 BCE to A.D. 1800" have made it possible to distinguish between tuberculosis strains that originated in the Old World and tuberculosis strains that originated in the New World.

Beyond the Conference

Denver's Julien Riel-Salvatore also reports some interesting new discoveries.

* Hunter-gatherers were turning wild plants into flour long before farming was invented.

A find in Utah shows flour being produced 10,000 years ago (long before plants were domesticated in the New World). The "milled seeds include sage, salt bush and various grasses, which were processed on grindstones."

Research at the "Gravettian site of Bilancino, in Tuscany, Italy, which dates to about 25,000 BP uncal [about 28,000 BP on a calibrated basis]. . . . includes notably charcoal, pollen and starch grain recovered from the surface of a grindstone. . . . [T]he occupants of Bilancino had been grinding cattail (Typha latifolia), likely its roots, as well as wild grasses to produce flour."

Why does this matter?

[I]t "implies the availability of an elaborate product, a flour, with high energy content, that is rich in carbohydrates, easily storable and transportable, to make a kind of bread (biscuits) or a porridge" . . . This means that plant material could be preserved and stored for much longer periods of time, which effectively can provide carbs during seasons such as winter during which they are normally difficult if not impossible to obtain. Also, it provides a subsistence items that serves as a buffer against the fluctuating availability of other types of subsitence resources, such as animal tissue. Lastly, because flour is easily ingested and digested, it also provides a foodstuff that both very young and very old members of a group can consume - and maybe even produce while adults are off procuring other things. This means that survival to adulthood and into old age can be facilitated, which has the potential of significantly reorganizing the way labor is divided within a society, and increasing the generational knowledge available to given forager groups.

These finds also further supports the evidence from a variety of sources that modern humans may have had proto-agricultural societies existed for thousands of years before plants were domesticated in a way that made them more useful and permitted a more settled lifestyle with more dense populations.

* Todd A. Surovell of the University of Wyoming gave a talk at DU yesterday that examined megafauna extinctions in the Americas. His key points were as follows:

Humans first arrived in North America approximately 14,000 years ago. Over the next two millennia, some 35 genera of Pleistocene megafauna suffered extinction. While it is tempting to see causality in this chronological correlation, after more than 80 years of fieldwork concerning the Pleistocene human occupation of the Americas, we can only demonstrate with confidence that humans hunted at most five species of extinct fauna.

He argued "that a huge amount of circumstantial evidence points to humans as the primary causal agents of extinction," so that it is unreasonable to insist on that this human cause can be established only with direct evidence that humans caused the extinction of the other species of extinct fauna.

* Anthropology.net explores a new paper on the population genetics of Central Asia providing the author's own analysis while discussing two other reviews of the paper's implications in the blogosphere. Linguistic and genetic evidence is used to parse out the extent to which Indo-Iranian (from at least the Bronze Age ca. 2000 BCE), then Turkic (5th-10th century CE), and then Mongolian (13th century CE) layers in the last couple thousand years have left distinct surviving ethnic groups or have assimilated each other.

The general trend is unsurprising. Central Asia has a West to East gradient of genetic influence. To the West, there are stronger traces of Indo-European populations; to the East, there are stronger traces of Turkic and Mongolian populations. But, the waves are distinguishable.

"The analysis of genetic variation reveals that Central Asian diversity is mainly shaped by linguistic affiliation, with Turkic-speaking populations forming a cluster more closely related to East-Asian populations and Indo-Iranian speakers forming a cluster closer to Western Eurasians." . . . [Turkic language speaking peoples] remained more genetic and linguistically unified and did not assimilate into Iranian genetics and languages. . . they did not absorb large populations of Iranians as their genetics and languages remained more separate than integrate.

Beware that the word "Turk" is false friend: "The Turks of Turkey are overwhelming derived from the same source populations as their Balkan (because of Rumelian Turks), Iranian, and Armenian, neighbors." The Northeast Asian people who gave rise to the language family to which Turkish belongs conquered Turkey at the far Western extent of their expansion and their rule led the people that they governed to switch from Indo-European languages to Turkic languages, but genetic descendants of these Northeast Asian peoples were largely limited to a ruling elite.

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