Researchers believe that the last population of woolly mammoths may have been wiped out by a "random event," despite signs of inbreeding and low genetic diversity.
The last population of the species was isolated on Wrangel Island, off the coast of Siberia, some 10,000 years ago due to rising global sea levels at the start of the Holocene period.
Their numbers dropped to as few as less than 10 individuals before the population recovered to between 200 and 300 within 20 generations, according to a study published on Thursday in the journal Cell. Some 6,000 years later the mammoth species became extinct.
"Despite recovering from a near-extinction event to approximately 300 reproducing individuals, our findings reveal persistent inbreeding depression," said Stockholm University's Love Dalén.
"These findings suggest that the mammoths were suffering from genetic diseases for hundreds of generations after the recovery."
What eventually wiped out the population on the island however remains a mystery for the researchers, who sequenced genomes from 21 woolly mammoths for the study, saying that there appeared to have been a very rapid decline in population size.
"We can now confidently reject the idea that the population was simply too small and that they were doomed to go extinct for genetic reasons," Dalén said. "This means it was probably just some random event that killed them off, and if that random event hadn't happened, then we would still have mammoths today."
"The quest to find out what happened to the very last mammoths continues" said Dalén.
"Mammoths are an excellent system for understanding the ongoing biodiversity crisis and what happens from a genetic point of view when a species goes through a population bottleneck because they mirror the fate of a lot of present-day populations," said Marianne Dehasque from the Centre for Palaeogenetics, a joint venture between Stockholm University and the Swedish Museum of Natural History.