A brown-haired rhino that weighed two tons once roamed northeastern Siberia before mysteriously disappearing about 14,000 years ago. Was it caused by its destruction by humans, or the warming climate of the time?
A new study by a Swedish and Russian scientific team that examined DNA fragments from the remains of 14 of these prehistoric mammals allows our species to be removed.
They say that the animal population – also known by its scientific name Old Coelodonta – remained stable for millennia as they lived alongside humans, before falling sharply towards the end of the last ice age.
“This makes it more predisposed that climate change that occurred about 14,000 years ago is the main driver of extinction, rather than humans,” said Love Dalen, a geneticist at the Swedish Center for Paleeogenetics in Sweden.
Dalen led the study that was published in the journal Current biology on Thursday.
How did they come to that conclusion from the strands of DNA taken from the remains of frozen animals on earth for thousands of years?
The size of a population of a species is proportional to the level of its genetic diversity and the degree of inbreeding, Dalen said.
The team was able to analyze the complete genome of a rhino dating from 18,500 years ago.
Comparing chromosomes inherited from mother and father, they determined that inbreeding was low and diversity was high.
“An individual’s genome 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 have belonged to a large population” going back tens of thousands of years.
From other animals they were able to harvest mitochondrial genomes – which were passed down from mother – and from this they could estimate the size of the female population over time.
Humans arrived in this part of Siberia 30,000 years ago. Although they hunted rhinos, the animal population remained stable for another 12,000 years until a sudden warming period known as the Bolling-Allerod.
The same team previously published the genome of another megaherbivore, the wool mammoth – and believe me, this species also became extinct due to climate change, not human hunting.
Their conclusions are still being debated among the scientific community.
A major difference is that the Mammoths became extinct twice: those in Siberian territory became extinct at the same time as rhinos, but several hundred survived on Wrangel Island six millennia longer.
Today, the nearest rhino-wool living family is the Sumatran rhino. Often poisoned and facing the destruction of their habitat, there are fewer than 80 left in existence.
Here, no one can argue that people are innocent.
© Agence France-Presse