24,000 years ago the climate was really bad
A paper, just published in the prestigious international peer-reviewed journal Quaternary Science Reviews, provides compelling evidence in favour of the view that the last Neanderthals went extinct as a result of climate change.
Scientists from the University of Granada teamed up with colleagues from the Gibraltar Museum, Stanford University in California and the Institute for Research on Earth Evolution in Yokosuka (Japan) to correlate the human presence in southern Iberia between 40 and 20 thousand years ago with detailed climatic data for that period obtained from a deep sea sediment core taken in the Balearic Basin (ODP Site 975).
The paper, entitled Climate forcing and Neanderthal extinction in Southern Iberia: insights from a multiproxy marine record, reveals that conditions in southern Iberia became highly inhospitable around 24 thousand years ago. The Neanderthal extinction appears to be linked to these extreme conditions. These were, in fact, the most severe conditions experienced in this part of the world for a quarter of a million years. An armada of icebergs reached the Portuguese coast and the lowest annual mean sea surface temperatures (around 8°C) for a quarter of a million years were reached in the Strait of Gibraltar and the Alboran Sea, It appears that the cause was a combination of the rearrangement of current circulation and reduced solar radiation caused by changes in orbital geometry. On land, many continental areas of southern Iberia became arid and dominated by steppe plants. Linked to this is evidence of increased input of wind blown sand which appears to be related with the increased aridity at that point.
Overall conditions were severe but also highly variable at short time scales and this appears to have affected many stressed populations of animals and the Neanderthals. The climate changes did not just affect the Neanderthals but also caused a significant readjustment of modern human populations. Some traditional modern human cultures also disappeared and the emergence of a new modern human culture, the Solutrean, coincides with this climatic event. It now seems clear that rapid climate change not only caused the demise of the last Neanderthals on the planet but that it also generated significant cultural transformations among modern human groups. Those that managed to scrape past this event were our ancestors.
Clive Finlayson, Geraldine Finlayson and Darren F.a of the Gibraltar Museum are co-authors of this paper.