The extinction of the Neanderthals is one of the eeriest unsolved mysteries in paleontology. These European hominids were so closely related to humans that significant interbreeding occurred between the species, but the exact reasons that they were wiped out 40,000 years ago, while humans flourished, is still contested.
Among the usual suspects accused of killing off the Neanderthals is the Campanian Ignimbrite (CI), a catastrophic volcanic eruption in Italy that induced significant global climate change. But according to a new study published this week in Geology, the atmospheric aftershocks of the blast would not have been enough to have edged out the Neanderthals.
It seems that after decades of being on probation, the CI explosion may finally be cleared of contributing to the fall of our ill-fated Neanderthal cousins.
"We conclude that the environmental effects of the Campanian Ignimbrite eruption alone were insufficient to explain the ultimate demise of Neanderthals in Europe," the authors, led by Berkeley geologist Benjamin Black, wrote in the study's abstract.
"Nonetheless, significant volcanic cooling during the years immediately following the eruption could have impacted the viability of already precarious populations and influenced many aspects of daily life for Neanderthals and anatomically modern humans," the team added.
Black and his colleagues back up this claim with a comprehensive climate model of Pleistocene Europe in the wake of a CI-sized disaster. This eruption was the most powerful volcanic event Europe has experienced for 200,000 years, and as the simulations confirmed, it wreaked havoc on the planet's climate in a major way. Scientists estimate that it spewed up about 150 cubic kilometers of magma, and belched about 200 million tons of sulfur dioxide into the stratosphere.
Black's team simulated the global effect of this massive explosion using 3D climate models developed for aerosols. The researchers found that climate disruptions would have been far worse in Eastern Europe and Asia than in Western Europe, where Neanderthals and their human neighbors were uneasily coexisting. The winter following the eruption would have been pretty rough for the two hominid species, but the long-term aftershocks were not powerful enough to entirely snuff out the Neanderthals.
Paleontological problems like these are often solved by process of elimination, rather than by the discovery of some kind of smoking gun specimen, and that may be the case here. If this devastating volcanic eruption can be ruled out as a cause, then what remains? Human encroachment is a longstanding frontrunner, as is the notion of a virulent Neanderthal-specific pandemic, or a particularly brutal famine.
Clearly, there is still a lot of uncertainty surrounding the events that led to the Neanderthal extinction. But as this new research demonstrates, scientists are slowly but surely winnowing down the details of the last days of evolutionary doppelgangers.