The mammoths that once roamed North America were open to breeding with other species -- and may have done so extensively.
The woolly mammoth is the most famous species of the extinct genus Mammuthus that lived from the Pliocene epoch, which began about 5 million years ago, until they went extinct about 4,500 years ago.
But many species of mammoths -- rom the pony-sized pygmy mammoth to the huge, hairless Columbian mammoth -- once lived where Canada, Mexico and the United States exist today.
A study published this week in the journal Frontiers in Ecology and Evolution found that those species were open to diverse and exotic mates, reported CBC News.
The Columbian mammoth, a mostly hairless mammoth larger than an African elephant, lived in the temperate grasslands of the U.S. and Mexico, while the pony-sized pygmy mammoth lived on the islands off the coast of California.
The woolly mammoth lived in the same areas as the Columbian mammoth -- and new DNA evidence suggests those two species interbred to produce an entirely new animal.
Jefferson's mammoth, which roamed the woodlands of the Great Lakes region, is described as a cross between a woolly mammoth and Columbian mammoth, and researchers now believe that's exactly what the species was.
Woolly mammoths have been more extensively studied than other species, because their remains and DNA have been well preserved in the permafrost.
But a team of researchers led by Hendrik Poinar, a McMaster University geneticist, developed a technique that would allow DNA to be extracted and identified, even when little evidence exists.
They collected evidence from teeth and other specimens found in North America and Siberia, and discovered that DNA from various species of mammoths were surprisingly similar -- even when they looked dramatically different.
The researchers concluded the species, which had evolved over the roughly 1 million years after their arrival from Asia, could interbreed when they encountered one another.
Even though the mammoth species had evolved to look very different, the new evidence shows they were biologically the same but different ecological species.
Those differences allowed the woolly mammoth to survive climate change much longer than their hairless relatives, the Columbian mammoth.