Inbreeding killed off mammoths 4,000 years ago
Woolly mammoths used to roam the northern hemisphere. They lived in North America, Europe, Asia and Beringia. When the last Ice Age ended, approximately 11,650 years ago, woolly mammoths went into decline.
Extinction came in stages. By 10,500 years ago woolly mammoths were extinct on the continental mainlands. Small populations survived on two islands, St Paul in the Bering Sea and Wrangel in the Arctic Sea.
The St Paul mammoths lived until 5,600 years ago. On Wrangel Island they survived longer, finally dying out 4,000 years ago.
Studies of the Wrangel Island mammoths suggest they died out because the population was not genetically viable. It’s thought that there were only 300 to 500 individuals so genetic mutations spread between them.
For inbreeding to be avoided, the mammoths would have needed a population of at least 1,000 individuals. That was never possible, as the island only had capacity for up to 800 mammoths.
In 2019 scientists compared Wrangel Island mammoth DNA with the DNA of mainland mammoths and the DNA of modern elephants. They found mutations in the Wrangel DNA that were not present in the comparison samples.
The scientists carried out further research to predict the harmfulness of the mutations. This process included looking at diseases in other species.
Finally, they concluded that the mutations related to balance and coordination, male fertility, diabetes and the ability to smell flowers. Not being able to detect floral fragrances would have been devastating for mammoths. It would have affected their ability to find food.
Scientists don’t know how widespread these mutations were, but the small population size suggests that bad DNA would have been a significant problem.