STUDY: Humans, not climate change, responsible for extinction of large mammals over last 50,000 years
Although dramatic climate changes during the last interglacial and glacial periods affected populations of animals worldwide, significant extinctions has been observed only among large animals. Early modern humans were effective hunters of even the largest animal species. Archaeologists have found traps designed for very large animals, and analyses of ancient human bones and spear points show that they hunted and ate the largest mammals. These large animals were and are particularly vulnerable to overexploitation because they have long gestation periods.
SCIENCE DAILY: The debate has raged for decades: Was it humans or climate change that led to the extinction of many species of large mammals, birds, and reptiles that have disappeared from Earth over the past 50,000 years?
By “large,” we mean animals that weighed at least 45 kilograms — known as megafauna. At least 161 species of mammals were driven to extinction during this period. This number is based on the remains found so far.
The largest of them were hit the hardest — land-dwelling herbivores weighing over a ton, the megaherbivores. Fifty thousand years ago, there were 57 species of megaherbivores. Today, only 11 remain. These remaining 11 species have also seen drastic declines in their populations, but not to the point of complete extinction.
A research group from the Danish National Research Foundation’s Center for Ecological Dynamics in a Novel Biosphere (ECONOVO) at Aarhus University now concludes that many of these vanished species were hunted to extinction by humans. They present this conclusion in a review article invited by and published in the scientific journal Cambridge Prisms: Extinction…
The dramatic climate changes during the last interglacial and glacial periods (known as the late Pleistocene, from 130,000 to 11,000 years ago) certainly affected populations and distributions of both large and small animals and plants worldwide. However, significant extinctions were observed only among the large animals, particularly the largest ones…
“The large and very selective loss of megafauna over the last 50,000 years is unique over the past 66 million years. Previous periods of climate change did not lead to large, selective extinctions, which argues against a major role for climate in the megafauna extinctions,” says Professor Jens-Christian Svenning…
Archaeologists have found traps designed for very large animals, and isotope analyses of ancient human bones and protein residues from spear points show that they hunted and ate the largest mammals.
Jens-Christian Svenning adds, “Early modern humans were effective hunters of even the largest animal species and clearly had the ability to reduce the populations of large animals. These large animals were and are 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.”
The analysis shows that human hunting of large animals such as mammoths, mastodons, and giant sloths was widespread and consistent across the world.
It also shows that the species went extinct at very different times and at different rates around the world. In some local areas, it happened quite quickly, while in other places it took over 10,000 years. But everywhere, it occurred after modern humans arrived, or in Africa’s case, after cultural advancements among humans…
The researchers point out that the loss of megafauna has had profound ecological consequences. Large animals play a central role in ecosystems by influencing vegetation structure (e.g., the balance between dense forests and open areas), seed dispersal, and nutrient cycling. Their disappearance has resulted in significant changes in ecosystem structures and functions. SOURCE…
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