This is Scientific American 60 Second Science. I'm Emily Schwing. Got a minute?

It's long been thought, mammoths and mastodons rambled over North America's Arctic and sub-artic realms between 75 And

Rambled over North America's Arctic and sub-artic realms between 75 and 10,000 years ago

and were made extinct by hungry new arrivals on the scene,

human beings. But new evidence indicates Mastodons probably roamed the region as far

back as 120,000 years ago and they were gone before the first people showed up.

For at least the story with the Mastodon we now know that in what we call

Beringia, Alaska, parts of Yukon and over into northeastern Asia, they were wiped out in those

areas for things that had nothing to do with humans because they all died out before there were humans there.

Pat Drucken Miller is the curator of Earth Science at the University of Alaska Museum of the North.

Humans could not have been part of the story and that's pretty interesting.

The research is in the proceedings of the National Academy of Sciences.

Druckenmiller and co-authors were led to these conclusions after colleagues at the

Yukon Paleontology program in Canada decided to redate nearly 40,000 specimens

because American mastodons are often mistaken for their much hairier woolly mammoth cousins who hung around the area later.

A mammoth and a mastodon can be immediately distinguished on the basis of their teeth, their big cheek teeth.

The surface of a mammoth tooth looks like a washboard, perfect for grinding grasses that

grew during the last ice age.

But Mastodon teeth have much lumpier, bumpier cusps, ideal for chewing twigs and leaves.

People in the past when they found these teeth and bones, they put glue and other kind of strange things

on them. That glue actually can mess up the dates.

Gives you a wrong date. In fact, it gives you a date that's too young.

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