Remaking History: A New Take on How Evolution Has Shaped Modern Europeans

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Investigators reporting in the Cell Press journal Trends in Genetics say that analytical techniques are changing long-held, simplistic views about the evolutionary history of humans in Europe. Their findings indicate that many cultural, climatic, and demographic events have shaped genetic variation among modern-day European populations and that the variety of those mechanisms is more diverse than previously thought.

 

Recent advances in paleogenetics are providing never-before-seen glimpses into the complex evolution of humans in Europe, helping researchers piece together the events that ultimately created what is now known as modern man. Following the period when ice sheets were at their maximum extension across Earth (between 27,000 and 16,000 years ago), hunter-gatherer populations re-colonized most parts of Europe. Then around 8,000 years ago, the first farming populations appeared on the continent during the so-called Neolithic transition. For several thousand years, two separate modes of life coexisted in Europe: hunter-gatherer populations continued to rely on wild food resources, while farming populations had an entirely different demographic profile and lifestyle that consisted of domesticated crops and livestock, pottery, housing, and storage technology.

 

For some decades, it was assumed that the genetic diversity of contemporary Europeans was shaped mainly during the Neolithic transition; however, it now appears that it was also affected both before and after this key event. Moreover, the spread of farming is likely to have varied to a great extent by region, leading to varying impacts of migrating farmers’ and local hunter-gatherers’ genetic contributions to future populations. “We are currently at a stage in which next-generation sequencing technologies, ancient DNA analyses, and computer simulation modeling allow us to obtain a much more accurate and detailed perspective on the nature and timing of major prehistoric processes such as the colonization of Europe by modern humans, the survival of human populations during the ice age, the Neolithic transition, and the rise and fall of complex societies and empires,“ says first author Dr. Ron Pinhasi, of Trinity College Dublin, in Ireland. “The development of inter-disciplinary approaches is crucial to elaborate realistic models of human evolution.“ explains Dr. Mathias Currat. “These methods and technologies hold great potential to shed new light on past genetic variation, the onset of major cultural and technological changes that left their imprint on past and present genomes, and potentially on the impact of changes in lifestyle and demography on the appearance of certain diseases and genetic disorders“ says Dr. Pinhasi.


 

Why did humans replace Neanderthals? Paleo diet didn’t change, the climate did

 

Why were Neanderthals replaced by anatomically modern humans around 40,000 years ago? One popular hypothesis states that a broader dietary spectrum of modern humans gave them a competitive advantage on Neanderthals. Geochemical analyses of fossil bones seemed to confirm this dietary difference. Indeed, higher amounts of nitrogen heavy isotopes were found in the bones of modern humans compared to those of Neanderthals. However, these studies did not look at possible isotopic variation of nitrogen isotopes in the food resource themselves. In fact, environmental factors such as aridity can increase the heavy nitrogen isotope amount in plants, leading to higher nitrogen isotopic values in herbivores and their predators even without a change of subsistence strategy.

 

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Fragment of jaw of a wolf from Le Moustier that was analyzed during the investigation.
Credit: Herve Bocherens/University of Tubingen

 

Why were Neanderthals replaced by anatomically modern humans around 40,000 years ago? One popular hypothesis states that a broader dietary spectrum of modern humans gave them a competitive advantage on Neanderthals. Geochemical analyses of fossil bones seemed to confirm this dietary difference. Indeed, higher amounts of nitrogen heavy isotopes were found in the bones of modern humans compared to those of Neanderthals, suggesting at first that modern humans included fish in their diet while Neanderthals were focused on the meat of terrestrial large game, such as mammoth and bison. However, these studies did not look at possible isotopic variation of nitrogen isotopes in the food resource themselves. In fact, environmental factors such as aridity can increase the heavy nitrogen isotope amount in plants, leading to higher nitrogen isotopic values in herbivores and their predators even without a change of subsistence strategy.

 

A recent study published in Journal of Human Evolution by researchers from the University of Tubingen (Germany) and the Musee national de Prehistoire in Les Eyzies-de-Tayac (France) revealed that the nitrogen isotopic content of animal bones, both herbivores, such as reindeer, red deer, horse and bison, and carnivores such as wolves, changed dramatically at the time of first occurrence of modern humans in southwestern France. The changes are very similar to those seen in human fossils during the same period, showing that there was not necessarily a change in diet between Neanderthals and modern humans, but rather a change in environment that was responsible for a different isotopic signature of the same food resources. Moreover, this isotopic event coinciding in timing with the replacement of Neanderthals by modern humans may indicate that environmental changes, such as an increase of aridity, could have helped modern humans to overcome the Neanderthals.

 

These new results, together with recently published research showing that Neanderthals had more skills and exploited more diverse food resources than previously thought, makes the biological differences between these two types of prehistoric humans always smaller. In this context, the exact circumstances of the extinction of Neanderthals by modern humans remain unclear and they are probably more complex than just a behavioral superiority of one type of humans compared to the other.


Sources:  Universitaet Tubingen. “Why did humans replace Neanderthals? Paleo diet didn’t change, the climate did.“ Herve Bocherens, Dorothee G. Drucker, Stephane Madelaine. Evidence for a 15N positive excursion in terrestrial foodwebs at the Middle to Upper Palaeolithic transition in south-western France: Implications for early modern human palaeodiet and palaeoenvironment. Journal of Human Evolution, 2014; DOI: 10.1016/j.jhevol.2013.12.015 and ScienceDaily.com

 

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