Climate change may have been the reason while wholly rhino is now extinct rather than human hunting, a recent study reveals.
The demise of woolly rhinoceros species: the enormous, hairy and colossal rump animals that roamed Eurasia until 14,000 years ago has been much debated. Some scientists think that the animal was hunted to extinction as remains were found near prehistoric human sites.
The study was published in Current Biology on August 13.
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DNA Analysis Point Climate Change
Researchers report that based on genome study on the ancient DNA from woolly rhino found in north-east Siberia, climate change is the culprit for its extinction.
The research team studied the DNA from tissue, bone, and hair samples from 14 individuals to explore the study of the stability of its population in Siberia and found that reveal it remained stable and diverse until only a few thousand years before it became extinct.
They also studied the genetic diversity and thus were able to estimate population sizes and incidences of inbreeding. They also noted that there was an increase in population at the start of a cold period which was 29,000 years ago.
Human presence was first recorded in northeastern Siberia fourteen or fifteen thousand years ago. It was also the same time that the woolly rhinoceros became extinct, thus the claim that humans hunted the animal to extinction.
However, according to Love Dalén, the senior author of the study and a professor of evolutionary genetics at the Centre for Palaeogenetics, recent discoveries reveal of human settlements at 30,000 years old which meant the decline towards the extinction of the woolly rhinoceros does not coincide with the settlement of humans in the region. Dalén cited that there might even be an increase during the period.
The study also indicated that the population was stable even after humans settled in Siberia, which contradicts the decline, expected if the woolly rhinos were hunted to extinction. Researchers noted that they did not see a reduction in population size after 29,000 years ago, and the inbreeding was low. They only had data from 18,500 years ago which was 4,500 years before the extinction.
The research team thinks that the decline must have been within the said period. For future studies, the team hopes to study the DNA of woolly rhinoceroses that lived in the crucial 18,500, the last genome that they sequenced towards their extinction years.
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Adaptation Mechanism to Cold Weather
The DNA analysis also revealed that woolly rhinoceros had a genetic mutation that helped them adapt to colder weather. One variation, the study showed was that they developed a particular receptor in the skin that sensed warm and cold temperatures. The said adaptation meant that the woolly rhinoceros was suited well to the cold northeast Siberian climate.
The population may have declined due to the high temperatures during a brief warming period known as Bølling-Allerød interstadial. The woolly rhinoceros also got extinct during the said period.
"Although we can't rule out human involvement, we suggest that the woolly rhinoceros' extinction was more likely related to climate, " Edana Lord, one of the authors, said.
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