Early Modern Humans Were Responsible for Megafaunal Extinction; Hunting Practices May Have Reduced the Population of Large Mammals

There has been one question that haunts researchers for over 200 years: was megafauna driven to extinction on Earth by human activity or climatic change? A new study seems to finally have the answer.

Megafaunal Extinction

Megafauna are huge mammals walking the face of the earth from much of the Pleistocene period, between 2.5 million and 11,700 years ago. They mean any animal with a mass of at least 99 pounds-elephant, mammoth, rhinoceros, and diprotodon.

At least 161 species of mammals were driven to extinction during the late Quaternary period. This number is based on the remains found so far.

The hardest-hit were the largest of these animals - weighing a ton or more and known as megaherbivores or land-dwelling herbivores. There were 57 species of such megaherbivores on Earth 50,000 years ago, but today, out of those, only 11 survive.

These 11 species that survive, however, have suffered such enormous population declines as to almost reach extinction.

Across the past 50,000 years, terrestrial vertebrate faunas have lost a high percentage of their big species; the bulk of the extinctions actually occurred at the Late Pleistocene and Early to Middle Holocene time periods.

The intensity and timing of extinction differed from one continent to another; still, it affected all biomes from the Arctic to the tropics very badly. Climate and the origin of humans were the only viable hypotheses so far available for the extinction.

Humans vs Climate Change

A team of experts from the Danish National Research Foundation's Centre for Ecological Dynamics in a Novel Biosphere, ECONOVO, at Aarhus University demonstrates that many of these vanished species were actually hunted to extinction by humans. The finding has been published in a paper entitled "The late-Quaternary megafauna extinctions: Patterns, causes, ecological consequences and implications for ecosystem management in the Anthropocene."

In this study, these researchers covered several fields of research that were directly related to large animal extinction. These include timing species extinction, dietary preferences of the animals involved, climate and habitat requirements, genetic estimates of past population sizes, and evidence of human hunting.

Dramatic climatic changes at the end of the Pleistocene must certainly have had an impact on populations and distributions of large and small animals and plants worldwide. Still, among the large animals, especially the biggest among them, significant extinctions have been noticed.

Most of these extinct species were adaptable and could occupy a wide range of environments, and thus their extinction cannot be blamed on the loss of some specific type of ecosystem due to climatic changes. Moreover, most of these species were temperate to tropical animals, and hence had to gain from the warming at the end of the last ice age.

Meanwhile, archaeologists have discovered traps designed for very large animals. Isotope analyses of ancient human bones and protein residues from spear point reveal they hunted and consumed the largest mammals.

As the lead author Jens-Christian Svenning points out, early modern humans were efficient hunters of even the largest animal species and obviously had the capacity to reduce megafauna population sizes. Large animals especially would have been vulnerable to overexploitation since most of them have a long gestation period, produce very few at a time, and take many years to achieve sexual maturity.