Humans definitively responsible for extinction of large animals, study finds

Over the past 50,000 years, terrestrial vertebrate faunas have experienced severe declines in large species (megafauna), with most extinctions occurring during the Late Pleistocene and early to mid-Holocene. Importantly, this extinction event is unique in its strong size bias compared to other Cenozoic extinctions (past 66 million years). For example, of 57 species of large herbivores (weighing over 1,000 kg), only 11 have survived to the present day. Debate regarding the causes has continued for over two centuries.

“The massive and selective disappearance of large animals over the past 50,000 years is unprecedented in the past 66 million years,” said Professor Jens Christian Svenning from Aarhus University.

“Past climate changes have not led to large-scale selective extinctions, arguing that climate played a major role in the extinction of large animals.”

“Another important pattern supporting the lack of a role for climate is that recent megafauna extinctions have hit climatically stable regions as hard as climatically unstable regions.”

Archaeologists have found traps designed to hunt very large animals, and isotope analysis of protein residues on ancient human bones and spear points reveals that they hunted and ate the largest mammals.

“Early modern humans were able to effectively hunt even the largest animal species and clearly had the capacity to reduce large animal populations,” Prof Svenning said.

“These large animals were and remain especially vulnerable to over-exploitation because they have long gestation periods, give birth to very small litters and take many years to reach sexual maturity.”

The analysis found that human hunting of large animals, such as mammoths, mastodons and giant sloths, was widespread and consistent around the world.

It also shows that the species went extinct at very different times and at different rates around the world.

In some areas it happened quickly, but in others it took more than 10,000 years.

But everywhere, it happened after the arrival of modern humans or, in the case of Africa, after human cultural advancement.

Species became extinct on every continent except Antarctica, and in every type of ecosystem, from tropical forests and savannas to Mediterranean and temperate forests and steppes, to Arctic ecosystems.

“Many extinct species could have thrived in a variety of environments,” Prof Svenning said.

“Therefore, their extinction cannot be explained by climate change that caused the disappearance of certain ecosystem types such as the Mammoth Steppe, which also contained only a few large animal species.”

“Most species live in temperate to tropical climates and would have actually benefited from the warming at the end of the last ice age.”

The researchers say the decline of large animals has serious ecological implications.

Macrofauna play a central role in ecosystems by influencing vegetation structure (e.g. the balance between dense forest and open areas), seed dispersal and nutrient cycling.

Their disappearance has led to major changes in ecosystem structure and function.

“Our findings highlight the need for active conservation and restoration efforts,” Professor Svenning said.

“Reintroducing large mammals can help restore ecological balance and maintain the biodiversity that evolved in ecosystems rich in large animals.”

of study Published in the journal Cambridge Prism: Extinction.

_____

Jens Christian Svenning others2024. Late Quaternary megafauna extinctions: patterns, causes, ecological impacts and implications for ecosystem management in the Anthropocene. Aarhus University. Cambridge Prism: Extinction 2: e5; doi: 10.1017/ext.2024.4

This article has been edited based on the original release from Aarhus University.