In 2024, researchers challenged a decades-old theory about the extinction of woolly mammoths that they didn't die out the way we thought

For years, scientists believed the last woolly mammoths disappeared because their isolated population became too inbred to survive. But a new 2024 study is changing that long-held view. By examining ancient DNA from Wrangel Island mammoths, researchers now believe a sudden event, rather than genetics alone, may have brought the species to an end.

New research published in the journal Cell suggests the story may be far more complex, as per a report by USA Today.

The study indicates that the final population of woolly mammoths living on Wrangel Island in the Arctic may have survived genetically for thousands of years before a sudden event ultimately wiped them out.


Researchers now believe that "some other form of sudden event, such as a disease outbreak or dramatic change in environment" may have caused their extinction instead of genetic decline alone.

How did the mammoths become isolated?

The study focused on Wrangel Island, located off the northeastern coast of Siberia, where a small group of woolly mammoths survived long after the species had disappeared elsewhere.

According to Love Dalén, senior author of the study and professor in evolutionary genomics at the Centre for Palaeogenetics in Stockholm, the mammoths became stranded as the Ice Age came to an end more than 12,000 years ago.

As massive ice sheets melted, rising sea levels submerged the land bridge that once connected Wrangel Island to the Siberian mainland.

"It's likely that mammoths happened to pass through Wrangel Island "right at the time when the sea level actually cut Wrangel off from the mainland, so they became stranded there," he added."

The researchers estimate that when the mammoths first became isolated, "Our analysis suggests that they were down to about eight reproducing individuals," Dalén said, as per a report by USA Today.

Despite such a small beginning, the population recovered surprisingly quickly.

"The population actually grew very rapidly, almost exponentially, up to 300 individuals within something like 20 generations."

Scientists are still uncertain why the island was able to support mammoths for more than 6,000 years, although Dalén noted that abundant plant life and the absence of large predators and humans may have played important roles.

What did the DNA analysis reveal?

To better understand the mammoths' final years, researchers examined the genomes of 21 Siberian woolly mammoths.

The study included DNA from 14 mammoths that lived on Wrangel Island between 9,200 and 4,300 years ago, along with seven mainland ancestors for comparison.

The genomes were reconstructed from nearly 400 DNA samples collected from mammoth bones, tusks and teeth, including specimens gathered during a 2017 expedition to Wrangel Island.

Researchers extracted powdered material from inside mammoth teeth using a dentist drill before purifying it to obtain DNA for analysis.

The genetic evidence showed that while the mammoths started with an extremely small breeding population, they remained genetically stable for thousands of years. This finding challenges the long-standing belief that inbreeding alone drove them to extinction.

What may have caused their extinction?

Although the mammoths survived on Wrangel Island for millennia, the study suggests their final disappearance likely happened quite suddenly.

Dalén said researchers concentrated on the last 200 years before the species vanished. "Our youngest genome is 4,300 years old, and all the data we have suggested mammoths go extinct at 4,100," he said. Scientists believe a small population of around 200 mammoths would have been especially vulnerable to unexpected events.

"A small population like 200 individual mammoths would probably be very sensitive to just a small change in environment," Dalén said.

Researchers have proposed several possibilities, including a brief climatic crisis or a brush fire that damaged the island's vegetation.

Another theory is that a pathogen, such as influenza carried by migratory birds, may have reached the island and spread through the isolated population.

"I don't know if we'll ever figure it out, but at least we have some ideas," Dalén said.

While the exact cause remains uncertain, the new findings suggest the final chapter of the woolly mammoth was likely shaped by an unexpected event rather than by inbreeding alone, challenging one of the most widely accepted explanations for the species' extinction.

FAQs

Where did the last woolly mammoths live?
They survived on Wrangel Island in the Arctic, off northeastern Siberia.

What does the new study suggest?
It suggests a sudden event, not just inbreeding, may have caused their extinction.