While some scientists explore the possibility of bringing back to life the now-extinct woolly mammoth species, others are trying to explain what caused its relatively sudden disappearance. A new study has found that the species acquired too many unnecessary DNA mutations which caused genetic disease and other problems.
Woolly mammoths were among the most common large herbivores roaming the plains of North America and Siberia. Scientists believe that they first developed more than 700,000 years ago, but their population started to decline quite suddenly, after the end of the last ice age which occurred around 10,000 years ago.
Scientists believe that the main cause of their quick disappearance was a combination of factors such as a warming climate and increased hunting by humans. Smaller population persisted on isolated islands in the north until they too vanished more than 3,700 years ago.
Now, a team of researchers from the University of California, Berkeley, managed to compare the genomes of two different woolly mammoth specimens. One specimen was 45,000-years old from Siberia while the other one lived around 4,300-years ago on the Wrangel Island, off the coast of Russia.
The younger specimen was among the last one of its species but provided the researchers with invaluable knowledge about the changes suffered by the species. They discovered that compared to the older mammoth, the younger specimen had suffered multiple mutations which proved harmful to the normal reproductive functions, which played a big role in the extinction of the species.
The scientists believe that while specimens living on isolated islands managed to avoid human hunters, the years of inbreeding led to the formation of harmful DNA mutations, which practically rendered natural selection completely ineffective.
Normally, in large populations groups, those types of mutations eventually disappear due to natural selection as they cannot compete with specimens which have other beneficial mutations. However, smaller groups have no available mechanism to address this issues and they eventually go extinct.
The researchers believe that the bad DNA mutations affected the olfactory receptors and urinary proteins, which, in turn, affected their social status and mate choice of the woolly mammoth. While the research was limited to only one specimen, the scientists believe that the same changes affected almost all the members of that population.
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