Scientists say freak occasion killed woolly mammoths

Scientists behind a new genomic study now claim the last woolly mammoths on Earth were wiped out in an extreme storm or a plague – which means if an extinction event hadn’t occurred, they might still be around to this day.

These giant Ice Age beasts traversed the then-tundras of North America, Europe and Asia as far back as 300,000 years ago. They later went extinct roughly 4,000 years ago on an isolated island off the coast of Siberia in the Arctic Ocean.

The latest analysis shows that a few hundred woolly mammoths were cooped up on small Wrangel Island for about 6,000 years, but scientists say they didn’t die due to inbreeding, The Guardian reported.

The long held theory was that woolly mammoths eventually racked up enough harmful genetic mutations to cause a ‘genomic meltdown.’

‘We can now confidently reject the idea that the population was simply too small and that they were doomed to go extinct for genetic reasons,’ said evolutionary geneticist Love Dalén at the Centre for Palaeogenetics, a collaboration between Stockholm University and the Swedish Museum of Natural History.

Woolly mammoths traversed the Ice Age tundras of North America, Europe and Asia as far back as 300,000 years ago. They later went extinct roughly 4,000 years ago on an isolated island off the coast of Siberia in the Arctic Ocean

Scientists now believe mammoths were killed off from a random event – such as a bird flu or a storm – and not from inbreeding as was previously thought 

‘This means it was probably just some random event that killed them off, and if that random event hadn’t happened then we would still have mammoths today,’ he continued. 

Dalén and his colleagues analyzed the genomes of 21 mammoth specimens found on Wrangel Island and the Siberian mainland, accounting for 50,000 years of existence.

Pictured: Professor Love Dalén

They found that the prehistoric creatures went through a ‘severe bottleneck’ once they were trapped on Wrangel Island due to rising sea levels as the earth was warming. 

At one point during the Holocene period (11,500 years ago to the present day), the total population was eight or fewer.

‘These findings suggest that Wrangel Island may have been founded by a single herd of woolly mammoths,’ according to the study. 

The authors of the study said you’d normally expect a species to undergo ‘an accelerated genomic decline,’ but that’s not what happened.

‘The population recovered quickly after the bottleneck and subsequently remained stable. More precisely, we even find evidence that the recovered population was large enough, or possibly changed its behavior, to avoid inbreeding with close relatives…throughout 6,000 years of island isolation,’ the study reads.

So if they were able to eventually avoid inbreeding, what killed them all?

Rising sea levels cut off Wrangel Island from the mainland, this kept a population of woolly mammoths alive for 6000 years after the mainland population had gone extinct

Wrangel Island, where woolly mammoths made their last stand as a species, is seen just above the northeastern tip of Russia

The tusk of an extinct woolly mammoth. It is about 4000 years old and was found on Wrangel Island

It’s not clear, and it will likely never truly be known with exact specificity, but Dalén believes something like a bird flu could have doomed the species.

Other theories the researchers pose include a severe weather event or a sudden accumulation of volcanic ashes, which would lead to a lack of food on the island. 

‘Perhaps the mammoths would have been vulnerable to that given the reduced diversity we identified in the immune system genes,’ Dalén said. 

‘Alternatively, something like a tundra fire, a volcanic ash layer or a really bad weather season could have caused a really bad growth year for the plants on Wrangel.’

‘Given how small the population was, it would have been vulnerable to such random events.

The stable population on Wrangel Island suggests that the remaining mammoths were killed by something like a plague rather than genomic collapse

‘It seems to me that maybe the mammoths just got unlucky.’

And while this might seem like a rather bleak story of sudden extinction, lead author Marianne Dehasque of Uppsala University says she prefers to see this as a positive.

She told MailOnline: In a way this is a hopeful message, because it shows that small populations are not necessarily doomed to extinction.’

That could spell good news for current species such as Siberian Tigers or Snow Leopards which have been reduced to extremely low population sizes. 

This new tale of how mammoths died off also holds a lesson for the world today as biodiversity wanes more and more each year. 

The World Wildlife Fund’s Living Planet Report of 2022 found that wildlife populations have declined by an average of 69 percent in the past 50 years. 

‘Mammoths are an excellent system for understanding the ongoing biodiversity crisis and what happens from a genetic point of view when a species goes through a population bottleneck because they mirror the fate of a lot of present-day populations,’ Dehasque said.