A two-ton, brown-haired rhino once roamed northeastern Siberia before mysteriously disappearing about 14,000 years ago. Was its collapse caused by man, or the warming climate of that time?
A new study by a team of Swedish and Russian scientists examined DNA fragments from the remains of these 14 prehistoric mammals to allow our species to escape the field of sight.
They say that the animal population – also known by its scientific name Old Coelodonta – remained stable for millennia when they lived with humans, before plummeting towards the end of the last ice age.
“That makes it more likely that the climate changes that happened around 14,000 years ago were the main cause of the extinction, not humans,”; said Love Dalen, geneticist at the Center for Paleontology. Sweden, told AFP.
Dalen leads the research published in the journal Current biology on Thursday.
How did they reach that conclusion from strands of DNA taken from animal remains frozen in the soil for thousands of years?
According to Dalen, the size of a species’ population is directly proportional to the degree of genetic diversity and the degree of inbreeding.
The team was able to analyze the complete genome of a rhino dating back 18,500 years ago.
By comparing chromosomes inherited from mother and father, they determined that inbreeding was low and diversity was high.
“An individual’s genome is a composite of all of its ancestors,” Dalen explains.
“18,000 years ago, that rhino belonged to a large population, and its ancestors must also belong to a large population” tens of thousands of years ago.
From other animals, they were able to collect the mitochondrial genome – passed down from the mother – and thus be able to estimate the size of the female population over time.
Humans came to this part of Siberia 30,000 years ago. Even though they hunt for rhinos, the animal’s population remains stable for another 12,000 years until a period of sudden warming known as Bolling-Allerod.
Previously, the team published the genome of another herbivore, the wool mammoth – and believed that the species is also extinct due to climate change, not hunting.
Their conclusions are still being debated in the scientific community.
One key difference is that the mammoths went extinct twice: those on mainland Siberia disappeared at the same time as the rhino, but several hundred have survived on Wrangel Island longer than six millennia.
Today, the closest relative of the wool rhino is the Sumatran rhino. Often poached and faced with the destruction of their habitat, fewer than 80 remain.
Here, no one can argue that humans have nothing to blame.
© Agence France-Presse