50,000 years ago, 57 giant species of animals roamed the Earth! Whose fault is it that there are only 11 today?
Human activity, not just climate change, has led to the extinction of Earth’s giant animals, underscoring the urgent need for conservation efforts to restore ecological balance.
Long after the dinosaurs disappeared, the Earth was teeming with colossal creatures. Giant sloths, woolly mammoths, giant wombats and kangaroos roamed the planet, along with the beautiful gigagoos. Between 50,000 and 10,000 years ago, nearly 200 of these large species disappeared, leaving only their massive bones and burrows as evidence. The reason for their disappearance has been a subject of debate until now.
During the period of that extinction, the Earth warmed and the Ice Age ended, pointing to climate change as a potential factor. At the same time, humans expanded into new territories and exploited the resources revealed by the retreating ice. This overlap has led to debates about the roles of climate change and human activity in these extinctions.
A recent study, published in the journal Cambridge Prisms: Extinction, which examines the decline of megaherbivores, suggests that human activity played a significant role in their extinction. The fossil record shows that at least 57 species of megaherbivores existed 50,000 years ago; today only 11 remain, including hippos, giraffes, rhinos and elephants, many of which are endangered.
Such a drastic reduction is probably not only due to climate change. The large and highly selective loss of megafauna in the last 50,000 years is unique in the past 66 million years. Previous periods of climate change did not lead to large, selective extinctions, which speaks against a major role of climate in the extinction of megafauna, explains Jens-Christian Svenning from the University of Aarhus in Denmark.
Another significant pattern that speaks against the role of climate is that recent megafauna extinctions hit climate-stable and unstable areas equally hard, Svenning adds.
A consistent pattern
The study looks at evidence from the dinosaur extinction, including locations and times of extinction, habitats and food preferences, population size, evidence of human hunting, human migrations and climate data. Evidence shows that humans coexisted with and hunted megafauna.
Early modern humans were efficient hunters of even the largest animal species and apparently had the ability to deplete large animal populations. 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, Svenning says.
Human hunting has contributed significantly to these extinctions. Megaherbivores thrived in different climate scenarios and adapted well to warmer environments. However, they disappeared after humans arrived and began hunting them. This pattern was consistent throughout the world.
The last mammoths on Wrangel Island outlived the mainland population probably due to the absence of humans. Today’s megafauna are also declining due to human exploitation, with 98 percent of these endangered species at risk.
Our results highlight the need for active conservation and restoration efforts. By reintroducing large mammals, we can help restore ecological balance and support the biodiversity that developed in megafauna-rich ecosystems, Svenning concludes.
