The reason why Neanderthals no longer walk the Earth has long remained a mystery, and now one group of scientists is taking a closer look at a major volcanic eruption that may have, at least in part, wiped out our early human ancestors.
The Campanian Ignimbrite (CI) eruption in Italy 40,000 years ago was one of the largest volcanic cataclysms on Europe. It spewed a significant amount of sulfur dioxide (SO2) into the stratosphere that blanketed the region and significantly lowered atmospheric temperatures. And while it did coincide with the final decline of Neanderthals, so did dramatic territorial and cultural advances among our ancestors, referred to as "anatomically modern humans".
Scientists have debated in the past whether or not this particular super-eruption triggered the final fall of the Neanderthals, with recent research saying that it wasn't enough to lower temperatures to be a significant contributor to their demise. Now, that same research team is testing this hypothesis further with a sophisticated new climate model.
"While the precise implications of the CI eruption for cultures and livelihoods are best understood in the context of archaeological data sets," the researchers said in a press release, the results of their study quantitatively describe the magnitude and distribution of the volcanic cooling and acid deposition around 40,000 years ago.
In their climate simulations, lead author Benjamin Black and his colleagues found that the largest temperature decreases after the eruption occurred in Eastern Europe and Asia - regions that did not include where final Neanderthal populations were living, which were in Western Europe. (Scroll to read on...)
What's more, according to radiocarbon dating, at the time of the CI eruption anatomically modern humans had already arrived and established themselves in Europe, and Neanderthal populations were already on the decline.
Both of these factors led the researchers to conclude that the CI eruption, however cataclysmic, was likely not enough to trigger Neanderthal extinction.
However, they do point out that the abrupt cold spell following the eruption - in which temperatures in Western Europe fell an average of 2 to 4 degrees Celsius (35.6-39.2 Fahrenheit) - did still have an impact on the day-to-day lives of Neanderthals, as well as early humans in the region. This study may not definitively show what led to the downfall of Neanderthals, but it does shed some light on how our ancestors coped with severe climate changes.
Some experts believe that their inferior intelligence caused "simple" Neanderthals to die out when competing for resources with early humans. But new studies have shown that they were actually just as smart as modern humans, even proving crafty enough to catch small and elusive prey like pigeons.
Another theory was that they simply bred into the ancestral human population after hooking up some 50,000 years ago, to the point that they were no longer recognized as their own sub-species. This seems to be the promising theory, as recent estimates have revealed that Neanderthal DNA makes up one to four percent of the modern Eurasian genome.
Neanderthals (Homo neanderthalensis) thrived between about 350,000 and 40,000 years ago in parts of Europe and Asia. According to the Smithsonian Institution, they are recognized by their large foreheads, angled cheekbones, huge noses, and short, stocky bodies.
They are our closest extinct human relative, but without further research, the exact placement of Neanderthals in our evolutionary history will continue to elude scientists.
The recent findings were published in the journal Geology.
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