Engraving of the hairy mammoth hunt
Prehistoric humans hunted the woolly mammoth. A growing body of research shows that this species—and at least 46 other megaherbivore species—was driven to extinction by humans. Credit: Engraving by Ernest Grise, photographed by William Henry Jackson. Courtesy of Getty’s Open Content program
Researchers of Aarhus University Researchers have concluded that hunting, rather than climate change, was the main driver of the extinction of large mammals over the past 50,000 years. This conclusion is based on an analysis of more than 300 scientific papers.
Over the past 50,000 years, many major speciesor megafauna, weighing at least 45 kilograms, have disappeared. Research from Aarhus University suggests that these extinctions were primarily caused by human hunting rather than climate change, despite significant climate fluctuations during this period. This conclusion is supported by extensive analyses integrating evidence of human hunting, archaeological data and studies from various scientific fields, demonstrating that human activity was a more decisive factor in these extinctions than previous dramatic climate changes.
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, called megafauna. At least 161 species of mammals became extinct during this period. This figure is based on remains found so far.
The largest of these have been the most affected: megaherbivores, terrestrial herbivores weighing more than a ton. Fifty thousand years ago, there were 57 species of megaherbivores. Today, there are only 11 left. These 11 remaining species have also experienced drastic population declines, but not to the point of disappearing completely.
A research group from the Centre for Ecological Dynamics in a New Biosphere (ECONOVO) of the Danish National Research Foundation at Aarhus University now concludes that many of these extinct species were hunted to extinction by humans.
Svenning and the Giant Sloth
Jens Christian Svenning in front of a fossilized skeleton of a giant ground sloth, Lestodon armatus, on display at the Museum of Natural History in New York. Credit: Else Magaard, Aarhus University
Many different research areas
They present this conclusion in an invited review article published in the scientific journal Cambridge Prisms: ExtinctionA review article synthesizes and analyzes existing research in a particular field.
In this case, researchers from Aarhus University integrated several research areas, including studies directly related to the extinction of large animals, such as:
The calendar of species extinctions
Animal Food Preferences
Climate and habitat requirements
Genetic estimates of past population sizes
Evidence of human hunting
In addition, they included a wide range of studies from other fields necessary for understanding the phenomenon, such as:
Climate history over the last 1 to 3 million years
History of vegetation over the last 1 to 3 million years
Evolution and dynamics of fauna over the last 66 million years
Archaeological data on human expansion and lifestyle, including dietary preferences
Climate change played a lesser role
The dramatic climate changes that occurred during the last interglacial and glacial periods (known as the Late Pleistocene, from 130,000 to 11,000 years ago) certainly affected the populations and distribution of animals and plants, large and small, around the world. However, significant extinctions were observed only among large animals, particularly the largest ones.
It is important to note that previous, equally dramatic glacial and interglacial periods over the past few million years did not result in selective loss of megafauna. Particularly at the beginning of the glacial periods, the new cold and dry conditions caused large-scale extinctions in some regions, such as trees in Europe. In contrast, there were no selective extinctions of large animals.
Charts on extinct mammals
This figure shows how the extinction of large mammals during the end of the Quaternary is related to their body size. At the top, you can see the global percentage of species that went extinct based on their body size. The bottom part breaks it down by continent. The black numbers represent the total number of species that lived during this period, including those that still exist and those that went extinct. The red numbers indicate species that went extinct. Credit: Aarhus University ECONOVO / Cambridge Prisms: Extinction
“The massive and highly selective extinction of megafauna over the past 50,000 years is unique in the past 66 million years. Previous periods of climate change have not led to massive and selective extinctions, which argues against a major role of climate in megafauna extinctions,” says Professor Jens-Christian Svenning, who leads ECONOVO and is the lead author of the paper. He adds: “Another significant pattern that argues against a role of climate is that recent megafauna extinctions have hit climatically stable areas as hard as unstable areas.”
Effective hunters and vulnerable giants
Archaeologists have discovered traps designed for very large animals, and isotopic analyses of ancient human bones and protein residue from spear points show that they hunted and ate larger mammals.
Jens-Christian Svenning adds: “Early modern humans were effective hunters, even against the largest animal species, and clearly had the ability to reduce 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 constant throughout the world.
The study also shows that species went extinct at very different times and rates in different parts of the world. In some regions, extinction happened quite quickly, while 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 advances.
…in all types of environments
Species have disappeared 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 of the extinct species could have thrived in different types of environments. Their extinction cannot therefore be explained by climate change that led to the disappearance of a specific type of ecosystem, such as the mammoth steppe, which also only supported a few species of megafauna,” says Jens-Christian Svenning. “Most species lived in temperate to tropical conditions and should have benefited from the warming at the end of the last ice age.”
Consequences and recommendations
The researchers point out that the disappearance 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 led to significant changes in ecosystem structures and functions.
“Our results highlight the need for active conservation and restoration efforts. By reintroducing large mammals, we can help restore ecological balances and support biodiversity, which has evolved in ecosystems rich in megafauna,” says Jens-Christian Svenning.
Reference: “Late Quaternary Megafaunal Extinctions: Patterns, Causes, Ecological Consequences, and Implications for Ecosystem Management in the Anthropocene Era” by Jens-Christian Svenning, Rhys T. Lemoine, Juraj Bergman, Robert Buitenwerf, Elizabeth Le Roux, Erick Lundgren, Ninad Mungi, and Rasmus Ø. Pedersen, March 22, 2024, Cambridge Prisms: Extinction.
DOI: 10.1017/ext.2024.4
The study was funded by Villum Fonden, the Danish National Research Foundation and the Independent Research Fund Denmark.
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