Whatever killed the wooly mammoths, inbreeding wasn't it.
A new study published in the Molecular Ecology journal on Friday has found that human activity or environmental factors were the likely cause of death for the ancient creatures, BBC News reported.
Swedish and British scientists used crime scene techniques to analyze DNA samples of wooly mammoths taken from Wrangel Island in the Arctic Ocean, according to the BBC. They then compared the bones, teeth, and tusks from the island to samples found in Chukotka in north-east Siberia.
Because Wrangel Island is so small, it was initially thought that a close-knit population of mammoths inbred and caused a lack of genetic diversity that would have led to their demise, the report's co-author Dr Love Dalen, from the department of molecular systematics at the Swedish Museum of Natural History, told the BBC.
More from GlobalPost: Wooly mammoths to be cloned by Russian and Japanese scientists
When the total wooly mammoth population in Eurasia dipped from tens of thousands to very few during the Ice Age, there was a 30 percent decrease in genetic diversity. However, that is a normal drop, according to the scientists.
"When we examined the samples from the island, there reached a point when this reached a plateau and there was no more loss [of diversity]. This stage continued until the creatures became extinct," Dr Dalen said. "This therefore rejects the inbreeding theory. The mammoths on the island were isolated for nearly 6,000 years but yet managed to maintain a stable population."
Evolutionary geneticist and University College London Professor Mark Thomas said the team had "produced a significant moment in mammoth research," BBC reported.
"They examined the DNA of multiple samples and they showed that by having a constant size population, the Wrangel Island mammoths were not just doomed to die," Thomas said. "Something happened to kill all of them - but what that is we do not know yet. That is the next step."
Dr Dalen said further investigation was needed to determine their cause of extinction, but speculated that environmental change killed off the creatures.
"If humans hunted them to extinction, I would expect us to find evidence of that," he said.
More from GlobalPost: Wooly mammoth tusks among items seized by Russia customs