This is scientific American 60 second science.

I'm Christopher Intagiyata.

During the last ice age, the northern half of North America was blanketed by ice.

But along the Pacific coast of Canada, some land remained

bare. It was a place where animals and plants could thrive, and humans too.

Archaeologists have found stone tools and cave sites 12 to 13,000 years old in the coastal Pacific

Northwest. One find was a mastodon rib with a bony weapon in it, and now scientists at the

Hakai Institute and the University of

Victoria have made a spectacular discovery, clay soil trampled by human feet, the

oldest footprints uncovered in North America. Researchers were digging several feet below a modern day beach on British Columbia's

Calvert Island, about 250 miles northwest of Vancouver, when they discovered the tracks.

They found 29 in all.

Some had toes, arches, and heel prints,

indicating the people who left them were probably barefoot.

And using a shoe-sized measurement chart,

similar to the kind you find in a shoe store, they determine

that the footprints likely belong to a child and two adults, who lived and walked the area

some 13,000 years ago.

The results are in the journal Plus One. The tracks are not in a

line like the famous Latoli footprints in Tanzania. Instead they're facing

different directions, suggestive of people gathering.

Or perhaps the author's right, they could be the footprints of people getting out of a boat,

...