Thirteen thousand years ago, a small group of people walked on a beach on one of the thousands of low islands off the coast of British Columbia. These walkers were some of the first humans to settle here.

A team of archaeologists led by Duncan McLaren of the Hakai Institute and the University of Victoria unearthed 29 footprints on the shore of Calvert Island, British Columbia, embedded in a layer of light-brown clay 60cm below today’s sandy beach. Radiocarbon dating of a small piece of wood embedded in the clay puts the footprints at 13,317 to 12,633 years old, making them some of the earliest clear evidence of human presence this far north on Canada’s Pacific Coast.

The footprints offer proof that people were on the west coast of Canada in the final stages of the last glacial period, when a huge expanse of ice called the Cordilleran Ice Sheet stretched to Canada’s Pacific Coast. The ice sheet seems to have receded from the shoreline in patches, creating small areas of thawed land called refugia, just large enough to support plants and large animals—including humans, if they could get there. It’s possible that the first North Americans made their way south along the edges of the Cordilleran Ice Sheet after crossing the Beringia Land Bridge.

If that’s how it happened, then those early North Americans were likely using watercraft of some type to navigate the coastline. There’s no sign of a watercraft at Calvert Island—the earliest boat archaeologists have found anywhere is a 10,200- to 9,600-year-old dugout canoe from the Netherlands. Although the sea level at Calvert Island was two or three meters lower during the late Pleistocene than it is today, the island was still cut off from the mainland.

The footprints are an important addition to the relatively small body of evidence for human movement along the Northern Pacific Coast during the last ice age. Few archaeological sites from the period have been found this far north, and most of those are slightly earlier, from 12,700 to 11,800 years ago. A few older sites have been studied farther south in British Columbia and in the US Pacific Northwest and much farther south in South America, including a 14,000-year-old set of footprints in Argentina and a single 14,600-year-old footprint in Chile.

Ice Age beachcombers

The footprints belong to at least three people, based on their measurements. At least one of those was a child, who would have worn a juniors’ size 8 (US) in modern shoes. An adult in the group would have worn either a women’s size 8-9 or a men’s size 7-8. The third person may have been either a large child or a small adult, wearing either a junior’s size 1 or a women’s size 3 today.

The people who walked the beach of Calvert Island 13,000 years ago were all barefoot. Some of the tracks have clear impressions of toes, and analysis shows the others were also made by bare feet. A few are even clear enough that you can see, millennia later, that their feet slipped and slid while walking across the wet, slippery clay of the beach.

“An elongation of the heel of the foot[print] was found, likely caused by the pedestrian slipping forward in the substrate as they walked across it,” wrote McLaren and his colleagues.

And they were walking in several different directions, not all together in a straight line like the famous early hominin trackway at Laetoli, Kenya. Archaeologists say the beach was clearly an area with plenty of activity, not a place people just passed through in a line on their way somewhere else. Most of the tracks point generally north or northwest up the beach, though, and McLaren and his colleagues say the footprints could have been left by a group of people disembarking from an early watercraft and moving inland.

One set of prints (numbered 8 and 9 on the diagram) are clearly a matched pair—a left and right foot, side by side, marking the place where someone paused for at least a moment to stand on the beach, feet spread slightly, facing inland with their back to the wind.

Douglas McLaren

Douglas McLaren

Douglas McLaren

Douglas McLaren

Douglas McLaren

Douglas McLaren

The footprints were an unexpected surprise for the team of archaeologists, who had come to Calvert Island in 2014 looking for archaeological evidence of human presence, such as shell middens or stone tools. McLaren and his team did find some stone tools nearby in the same sediment layer, but none of them is a fluted projectile point of the Clovis style usually associated with early North Americans. Clovis points have never been found this far north on the Canadian coast, and it’s possible that late Pleistocene people moving along the margins of the Cordilleran Ice Sheet may have used unfluted projectile points instead.

When McLaren and his team unearthed the first footprint in 2014, the find was enough to bring them back to look for more the next year, when they found 28 clear footprints along with several other impressions that might have been partial tracks, all within an eight-square-meter excavation area. Although there are almost certainly other tracks on the island, the archaeologists say they won’t be back for more. They want to leave the rest of Calvert Island’s tracks undisturbed so that future archaeologists can study them with more advanced techniques.

And the archaeologists say there could be more Pleistocene tracks waiting to be discovered beneath the sand of British Columbia’s beaches. Shorelines are generally good places for preserving footprints, thanks to a combination of soft sediment, high traffic, and wind and waves quickly covering the footprints with a protective layer of new sediment.

PLOS ONE, 2017. DOI: 10.1371/journal.pone.0193522 (About DOIs).