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Why the woolly mammoth, giant sloth, and other large plant-eating animals went extinct about 50,000 years ago has long puzzled scientists.
Some paleontologists, biologists and others have argued that dramatic climate change events during the past two ice ages were responsible for the extinction of these massive creatures, but a new study focuses on a different culprit: humans.
A comprehensive review combining paleoclimate data, preserved DNA samples, archaeological evidence, and more has concluded that “human predation” by early hunter-gatherers is the most supported explanation by all the available evidence.
"There is strong, cumulative support for direct and indirect stressors from behaviorally modern humans," the team concluded in their new study.
Scientists said humans were the "main driver" behind the extinction of these species.
Scientists refer to large animals, defined as anything weighing more than 45 kg, as “megafauna.” Their higher-than-average extinction rates in modern times have caused both concern and fascination.
Svenning, who leads the Danish National Research Foundation's Centre for Ecological Dynamics in the New Biosphere (ECONOVO) at Aarhus University, led a team of seven other researchers who helped compile the new study.
An interesting array of artefacts and physical evidence from the archaeological record helped bolster their conclusions, which were published in the journal Cambridge Prisms: Extinction.
Ancient traps, designed by prehistoric humans to hunt very large animals, as well as analyses of human bones and protein residues on spears, indicate that our ancestors hunted and ate some of the largest mammals around.
"Another important pattern that argues against a role for climate is that recent megafaunal extinctions hit just as hard in climatically stable regions as in unstable ones," Svenning revealed.
But while the region's exposure to climate change played no role in these extinctions, Svenning's team found that the influx of human hunters did.
The fossil record shows that these large species went extinct at very different times and at widely varying rates, with some declining very quickly and others gradually, in some cases over 10,000 years or more.
Few of these extinctions match well with climate records from this time period, known as the Late Quaternary, which includes the end of the Pleistocene, the past two ice ages, and the dawn of the Holocene 11,700 years ago.
But many of these extinctions were associated with the emergence of modern humans.
"Early modern humans were effective hunters of even the largest animals, and clearly had the ability to reduce the numbers of large animals," Svenning noted.
“These large animals were particularly vulnerable to overexploitation because they have long gestation periods, produce very few offspring at a time, and take many years to reach sexual maturity,” he added.
English (US)