The terrifying event probably killed the last woolly mammoths, scientists say

The last woolly mammoths on Earth took their final stand on a remote Arctic island about 4,000 years ago, but the question of what sealed their fate has remained a mystery. Now a genetic analysis suggests that a freak event like an extreme storm or a plague was to blame.

The findings contradict an earlier theory that deleterious genetic mutations caused by bloodshed led to a “genomic meltdown” in the isolated population. The latest analysis confirms that although the group had low genetic diversity, a stable population of several hundred mammoths had occupied 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 they were doomed to extinction for genetic reasons,” said Prof Love Dalén, an evolutionary geneticist at the Center for Paleogenetics, run jointly by the Swedish Museum of Nature. History and Stockholm University. “That means it was probably just a random event that killed them off, and if that random event hadn’t happened, then we’d still have mammoths today.”

Woolly mammoths once roamed the vast expanses of the Ice Age in 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 posed an increasing threat, they retreated northward and died out on the continent about 10,000 years ago. Rising sea levels cut off a pocket population on Wrangel Island, which survived for another 6,000 years.

Dalén and colleagues analyzed the genomes of 13 mammoth specimens found at Wrangel and seven earlier specimens excavated on the continent, together representing a span of 50,000 years.

The findings, published in Cell, reveal that the Wrangel population went through a severe bottleneck, reduced to just eight breeding individuals at a time. But the group recovered to a population of 200-300 within 20 generations, which appears to have remained stable until the end.

Compared to their mainland ancestors, the Wrangel Island mammoth genomes showed signs of inbreeding and low genetic diversity, including in genes known to play a critical role in the vertebrate immune response. This suggests that the group would have been 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 goes through a population bottleneck, because they mirror the fate of many populations today,” said Marianne Dehasque, from Uppsala. University, first author of the paper.

Dr Vincent Lynch, a biologist at the University at Buffalo who was not involved in the research, said the findings provided new insights into the last days of mammoths and raised the possibility that a genetically compromised group was unable to answered an environment. change as a new pathogen.

“Extinction, at least when it’s not at the hands of humans, usually doesn’t come from just one cause,” he said. “It’s the result of a combination of factors like inbreeding, a small population size, an accumulation of deleterious mutations and, sometimes, bad luck.”