Our world was once home to many giants. Well, it wasn’t that long ago. After the dinosaurs died out, our planet became home to a whole host of giant animals, from sloths towering over humans to woolly mammoths, giant wombats, kangaroos and magnificent giant geese.
Somewhere between 50,000 and 10,000 years ago, about 200 of the world’s largest animal species vanished forever, leaving behind nothing but their massive bones. It’s unclear what ultimately took over these magnificent creatures.
During the time the megafauna disappeared, the world warmed and the ice ages ended, suggesting a potential mechanism: climate change. Meanwhile, our own species expanded into new lands in search of the resource wealth that came with the retreating ice. And so the debate over the role of these two potential contributing factors has intensified.
Now, a new study of the decline of giant herbivorous mammals (megaherbivores) points the finger at humanity. Fossils show that at least 57 species of megaherbivores existed 50,000 years ago. Today, these include the well-known hippos and giraffes, as well as various species of rhino and elephant, most of which are still in decline. The researchers say such a sharp decline is inconsistent with climate change being the sole cause.
“The massive and highly selective loss of megafauna over the past 50,000 years is unparalleled in the last 66 million years,” says Jens-Kristian Svenning, a macroecologist at Aarhus University in Denmark, who suggests that climate played a major role in the extinction of megafauna, as previous episodes of climate change did not lead to major selective extinctions.
“Another important model arguing against the role of climate is that recent megafauna extinctions affected climatically stable areas as hard as unstable areas.”
The new study is a comprehensive review of the available evidence since the dinosaurs went extinct 66 million years ago, including extinction locations and times, habitat and food preferences, estimated population sizes, evidence of human hunting, human population movements, and millions of years of climate and vegetation data.
We know that humans coexisted with megafauna, and we have evidence that some species were hunted to extinction. We know that our ancestors knew how to hunt large animals effectively.
“Early modern humans were effective hunters of even the largest animal species and clearly had the ability to reduce large animal populations,” Svenning says.
“These large animals were, and continue to be, 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.”
A new study shows that these human hunters were so efficient that they contributed significantly to many extinctions. The team found that megaherbivores went extinct in a variety of climate scenarios where they were able to thrive effectively even during the change. The researchers found that most were well adapted to warming.
And they died out at different times and at different rates, but all of those times were after humans arrived or developed the tools to hunt them. In fact, the exploitation of mammoths, mastodons, and giant sloths has been pretty consistent wherever humans have been. Perhaps the reason mammoths stayed on Wrangel Island after the mainland populations disappeared was because there were no humans there.
That’s a sobering thought, especially considering that the megafauna that survive today are being wiped out by human exploitation, according to a 2019 study . An estimated 98 percent of endangered megafauna species are at risk of extinction because humans won’t stop eating them.
“Our results highlight the need for proactive conservation and restoration efforts,” says Svenning. “By reintroducing large mammals, we can help restore ecological balance and support emerging biodiversity in megafauna-rich ecosystems.”
No wonder the rest of the animal world is afraid of us. The study was published on: Cambridge Prisms: Extinction.
Source: Port Altele
