Earth’s last wave of mammoths took their last stand on a remote Arctic island about 4,000 years ago, but the question of what sealed their fate remains a mystery. Now, genetic analysis suggests that a freak event, such as an extreme storm or plague, was to blame.
The findings contradict the previous theory that deleterious genetic mutations caused by inbreeding led to “genome collapse” in an isolated population. The latest analysis confirms that although the group had low genetic diversity, a stable population of several hundred mammoths inhabited the island for thousands of years before suddenly disappearing.
“We can now confidently reject the idea that the population was simply too small and that it was doomed to extinction for genetic reasons,” said Professor Love Dalén, an evolutionary geneticist at the Center for Paleogenetics, which is jointly run by the Swedish Museum of Natural History. History and Stockholm University. “That means it was probably just some random event that killed them, and if that random event hadn’t happened, we’d have mammoths today.”
Woolly mammoths once roamed the vast territories of Ice Age Europe, Asia, and the northern reaches of North America. After the global climate began to warm about 12,000 years ago, and as human hunters became an increasing threat, they retreated north and became extinct on land about 10,000 years ago. Rising sea levels cut off a pocket population on Wrangel Island that survived for another 6,000 years.
Dalén and colleagues analyzed the genomes of 13 mammoth specimens found on Wrangel and seven earlier specimens excavated on land, which together represent a span of 50,000 years.
The findings, published in Cell, reveal that the Wrangel population suffered a severe bottleneck, at one point down to just eight breeding individuals. But the group recovered to a population of 200-300 within 20 generations, which seems to have remained stable until the very end.
Compared to their ancestors on land, the genomes of Wrangel Island mammoths showed signs of inbreeding and low genetic diversity, including genes known to play critical roles in the vertebrate immune response. This suggests that the group would be more vulnerable to new pathogens such as plague or bird flu.
“Mammoths are an excellent system for understanding the ongoing biodiversity crisis and what happens genetically when a species passes a population bottleneck, as they mirror the fate of many current populations,” said Marianne Dehasque from Uppsala. University, first author of the article.
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Dr. Vincent Lynch, a biologist at the University of Buffalo who was not involved in the research, said the findings provided new insight into the last days of mammoths and raised the possibility that a genetically compromised group would have been unable to respond to the surrounding environment. a change such as a new pathogen.
“Extinction, at least when it’s not at the hands of humans, doesn’t usually result from just one cause,” he said. “It is the result of a combination of factors such as inbreeding, small population size, accumulation of deleterious mutations and sometimes bad luck.”