Climate change AND humans played crucial roles in the extinction of South America’s giant beasts

Human ancestors, sabre-toothed cats, giant sloths and other South America's beasts lived together for a long time, Australian study shows

By Ritwik Roy  

June 18 2016

 

A lynx looks from his cage at the Santillana del Mar's Zoo in northern Spain, March 12, 2005. With only around 100 lynxes left in southern Spain, the animal could soon be the first big cat species to become extinct since the sabre-toothed tiger disappeared 10,000 years ago, the WWF said. Reuters/Victor Fraile 

 

New study has revealed that climate change and human impact played a crucial role in the extinction of South America’s giant beasts such as sloths the size of elephants, one-tonne bears and sabre-toothed cats. Megafauna happily existed along with humans for nearly 3,000 years. However, as the climate rapidly warmed up, they became extinct within 300 years.

The study, published in the journal Science Advances, counter the earlier “Blitzkrieg” theory that says humans hunted into extinction the world’s biggest beasts. The new study also includes the effect of climate change for the demise of megafauna. The research was led by professor Alan Cooper from the University of Adelaide.

In order to trace the genetic history of the populations, Cooper and his teammates analysed ancient DNA from carbon-dated teeth and bones found in southern South American caves. They discovered that the megafauna disappeared around 12,300 years ago in a short span of 300 years. However, humans had been living in Monte Verde, Patagonia from about 14,600 years ago, the fossil record showed.

The team of scientists, including researchers from University of New South Wales, the US and Chile found that a rapid warming of South America’s climate led to the megafauna’s extinction. Geologist and palaeobiologist at Deakin University, Dr. Mark Warne, said that early human colonisation is almost always implicated with megafauna extinctions, Australian Geographic reports.

However, the new study suggests that human colonisation together with climate change were responsible for their extinction. It is kind of a revelation that at one point in time humans and megafauna lived together and no extinction happened. The moment warming happened, the megafauna was extinct in a few hundred years. The only large species to survive the extinction were the ancestors of today's llama and alpaca — the guanaco.

“The Americas are unique in that humans moved through two continents, from Alaska to Patagonia, in just 1500 years. As they did so, they passed through distinctly different climate states – warm in the north, and cold in the south.  As a result, we can contrast human impacts under the different climatic conditions,” professor Chris Turney, co-author of the paper and an expert in ancient climate change from the University of New South Wales, said in a statement.

The experts have also pointed out that Australia saw a prolonged overlap between megafauna and humans for nearly 11,000 years. Hence, Down Under, it was definitely not “Blitzkrieg.”

“What we see in Australia is a very prolonged period of overlap between humans and megafauna of about 11,000 years, so clearly it is not Blitzkreig,” Cooper told the ABC.

source