A woolly brown rhinoceros that waited two tons once roamed northeastern Siberia before mysteriously disappearing about 14,000 years ago. Was his death caused by humans, or by the warming climate of the time?
A new study by a Swedish and Russian team of scientists examining DNA fragments of the remains of 14 of these prehistoric mammals is getting us kind of hooked.
They say the population of the animal – also known by its scientific name Coelodonta antiquitatis – remained stable for millennia when living next to humans, before falling sharply towards the end of the last ice age.
“That makes it more likely that climatic changes that occurred about 14,000 years ago became the primary driver of extinction, rather than humans,” Love Dalen, a geneticist at Sweden’s Center for Palaeogenetics, told AFP.
Dalen led the study, which was published in the journal Current biology on Thursday.
How did they reach that conclusion from DNA strands taken from the remains of animals that had been frozen in the soil for thousands of years?
The size of a population of a species is proportional to its level of genetic diversity and the degree of breeding, Dalen said.
The team was able to analyze the entire genome of one rhinoceros dating from 18,500 years ago.
By comparing the chromosomes inherited from the mother and from the father, they determined that incubation was low and diversity high.
“The genome of one individual is a mosaic of all his ancestors,” Dalen explained.
“18,000 years ago that rhino belonged to a large population, and its ancestors must also belong to a large population” that went back tens of thousands of years.
From other animals, they were able to harvest mitochondrial genomes – which are passed on from the mother – and thus estimate the size of the female populations over time.
People arrived in this part of Siberia 30,000 years ago. Although they hunt on the rhino, the animal’s population remained stable for 12,000 years until an abrupt period of warming, known as the Bolling-Allerod.
The same team previously published the genome of another mega-herbivore, the woolly mammoth – and believe that this species is also extinct due to climate change, not human hunting.
Their conclusions are still being discussed among the scientific community.
An important difference is that the mammoths became extinct twice: those on mainland Siberia disappeared about the same time as the rhinos, but a few hundred survived on Wrangel Island six millennia longer.
Today, the closest living relative of the woolly rhino is the Sumatran rhino. Often strikes and stand for the destruction of their habitat, there are less than 80 left.
Here no one can claim that people are free from guilt.
© Agence France-Presse
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