![\"Last](\"https:\/\/images.newscientist.com\/wp-content\/uploads\/2024\/06\/26162454\/SEI_210496828.jpg\")
<\/div>An artist\u2019s impression of the last woolly mammoth<\/p>\n
Beth Zaiken<\/p>\n<\/div>\n<\/figcaption><\/figure>\n<\/p>\n
Around 10,000 years ago, a handful of woolly mammoths found themselves stranded on an island in the Russian Arctic, off the Siberian coastline. In the following millennia, this tiny herd, perhaps as few as eight individuals, grew to a stable population of between 200 and 300 mammoths before becoming extinct around 4000 years ago. They were the last known population of woolly mammals on Earth \u2013 and if it weren\u2019t for bad luck, it is possible they could have survived into the modern era.<\/p>\n
We know the story of these mammoths thanks to a genetic study conducted by Love Dal\u00e9n<\/a> at Stockholm University in Sweden and his colleagues. The team examined the DNA of 14 mammoths from Wrangel Island, plus seven from the mainland population prior to the small group being isolated by rising sea levels due to melting ice sheets \u2013 altogether covering 50,000 years of genetic history.<\/p>\n The researchers\u2019 analysis shows that, despite the small number of individuals, inbreeding wasn\u2019t the reason for the mammoths\u2019 demise. Dal\u00e9n says the population was successfully purging major harmful genetic mutations, even though minor ones were accumulating.<\/p>\n \u201cWe can show that, in all likelihood, inbreeding and genetic diseases did not cause the population to gradually decline towards extinction,\u201d he says. \u201cThe population was doing OK despite the inbreeding.\u201d<\/p>\n <\/p>\n A mammoth tusk found on Wrangel island<\/p>\n Love Dal\u00e9n<\/p>\n<\/div>\n<\/figcaption><\/figure>\n<\/p>\n However, the team found that individual mammoths were affected by genetic diseases, and this negative impact at the individual level kept going for thousands of years. \u201cThis means that endangered species today, who in most cases were bottlenecked very recently, are likely to continue suffering from genetic diseases for hundreds of generations into the future,\u201d says Dal\u00e9n.<\/p>\n He points to the Tasmanian devil as another example of a species that has become isolated on a large island after the mainland population went extinct and that is now suffering from low genetic diversity. This, in turn, affects the immune system, says Dal\u00e9n. When this is reduced, a population is more susceptible to decline when facing a new pathogen, such as the facial tumor disease that affects the devils<\/a>.<\/p>\n \u201cIt seems that natural selection was effective in removing potentially lethal mutations, but other, less severe ones gradually mounted,\u201d says Adrian Lister<\/a> at the Natural History Museum in London.<\/p>\n \u201cWhether this contributed to eventual extinction is uncertain, but it could have done, perhaps in combination with environmental change,\u201d says Lister.\u00a0 \u201cThere are lessons here for monitoring the genetic health of endangered species today.\u201d<\/p>\n Exactly what drove the mammoths to extinction is unclear, but intriguingly, the availability of freshwater lakes and rivers on Wrangel suggests they potentially could have survived for longer than they did, unlike a similarly isolated group that went extinct 5600 years ago due to drought<\/a>.<\/p>\n \u201cAll these things like diseases, short-term climate events, tundra fires, are things we consider random events,\u201d says Dal\u00e9n. \u201cAnd since they are random, there was nothing inevitable about them happening and therefore had they not happened, maybe mammoths would have survived on Wrangel until today, assuming humans didn\u2019t kill them off when they finally arrived.\u201d<\/p>\n Topics:<\/p>\n<\/section><\/div>\n![\"Wrangel](\"https:\/\/images.newscientist.com\/wp-content\/uploads\/2024\/06\/26163143\/SEI_210497169.jpg\")
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