Animals of Madagascar killed off by human expansion

By Mark Waghorn via SWNS

Madagascar's massive beasts were killed off by human expansion, according to new research.

Towering 10-foot-tall elephant birds, gorilla-sized lemurs and a puma-like predator called the giant fossa once roamed the island.

Then, after millions of years of evolution, they disappeared - in just a couple of centuries. The mystery has baffled scientists for decades.

Now a study has charted it to the arrival of a small group of Bantu-speaking African people 1,000 years ago.

It ended the isolation of a few hundred individuals descended from Malagasy ancestral Asians.

As the population grew rapidly and spread, the landscape changed - ending the reign of all large-bodied vertebrates that once lived there.

They also included grand tortoises and pygmy hippos. It was previously believed they were wiped out by indigenous hunters.

But the genetic study in Current Biology shows the extinction was more nuanced - linking it to the first major expansion.

Lead author Dr. Denis Pierron, of the French National Centre for Scientific Research, Toulouse, said: "This human demographic expansion was simultaneous with a cultural and ecological transition on the island.

"Around the same period, cities appeared in Madagascar and all the vertebrates of more than 10 kilograms (22lbs) disappeared."

Over the past 40,000 years, most megafauna - animals larger than a human - have gone. Woolly mammoths, saber tooth tigers and countless more no longer roam.

What’s remarkable about the crash in Madagascar is it occurred relatively recently. It has implications for today.

Many remaining giants, such as elephants and rhinos, are threatened or endangered.

Dr. Pierron said: "Our study supports the theory it was not directly the arrival of humans on the island that caused the disappearance of the megafauna, but rather a change in lifestyle that caused both a human population expansion and a reduction in biodiversity in Madagascar."

The haven in the Indian Ocean is one of the last land masses colonized by humans. More than 90 percent of its reptiles, plant life and mammals exist nowhere else.

It is home to 25 million people who speak an Asian language despite the island's proximity to East Africa. Their origins have long been an enigma.

They trace their roots back to Bantu and Austronesian speakers from Africa and Asia.

Beyond that, the history remained murky. Other groups who speak similar languages live more than 4,000 miles away.

An international team's MAGE (Madagascar Genetic and Ethnolinguistic) project visited more than 250 villages across the country over ten years.

Computer simulations of cultural and genetic human diversity showed rapid expansion over a few generations coincided with big creatures vanishing.

The technique could be applied to untangling the demographic history of ancient populations - even after two or more groups have mixed.

It also sheds fresh light on how past changes in human populations altered whole ecosystems.

While the efforts have led to a much better understanding of Madagascar's past, many intriguing questions remain.

Dr. Pierron added: "If the ancestral Asian population was isolated for more than a millennium before mixing with the African population, where was this population?

"Already in Madagascar or in Asia? Why did the Asian population isolate itself over 2,000 years ago?

"Around 1,000 years ago, what triggered the observed cultural and demographic transition?"