Stockholm, Sweden – The last woolly mammoths faced a mysterious demise on a remote Arctic island about 4,000 years ago. A recent genetic analysis has refuted the theory of a ‘genomic meltdown,’ suggesting instead that a sudden catastrophic event, such as an extreme storm or a plague, may have been responsible for their extinction.
The study, conducted by Prof Love Dalén, an evolutionary geneticist at the Centre for Palaeogenetics, revealed that despite having low genetic diversity, a stable population of a few hundred mammoths had thrived on the island for thousands of years before disappearing abruptly. This challenges the belief that inbreeding and harmful genetic mutations led to the downfall of the isolated mammoth population.
Woolly mammoths, once widespread across ice age Europe, Asia, and North America, retreated to the Arctic as the climate warmed and human hunters posed a threat. The population on Wrangel Island, isolated by rising sea levels, managed to survive for an additional 6,000 years after their mainland counterparts had gone extinct.
Analyzing the genomes of 13 mammoth specimens from Wrangel Island and seven from the mainland, researchers found that the island population experienced a severe bottleneck, falling to just eight breeding individuals at one point. However, the group managed to rebound to a population of 200-300 within 20 generations, maintaining stability until their disappearance.
Compared to their mainland ancestors, the Wrangel Island mammoths exhibited signs of inbreeding and low genetic diversity, making them more susceptible to new pathogens. This vulnerability suggests that a plague or other disease could have played a role in their extinction.
Researchers emphasize that mammoths provide valuable insights into biodiversity crises and the impact of population bottlenecks on genetic health. Dr. Vincent Lynch, a biologist at the University at Buffalo, notes that extinction is often caused by a combination of factors, including inbreeding, genetic mutations, and environmental changes.
The findings shed light on the final days of the woolly mammoths and underscore the importance of genetic diversity in ensuring the survival of species facing environmental challenges. The study offers a cautionary tale about the risks of population bottlenecks and highlights the role of chance events in shaping the fate of entire species.