A typical teenager’s stroll: Carrying a baby and dodging mammoths

What could make you walk miles across a landscape full of Ice Age predators, all alone except for the toddler you’re carrying? Archaeologists recently discovered a long trail of footprints left behind by someone brave enough—or desperate enough—to undertake the journey.

Sometime between 10,000 and 15,000 years ago, a rather small person, probably a young teen or a short adult woman, walked quickly across the Pleistocene landscape. Mammoths and a giant ground sloth crossed the tracks in the travelers’ wake, trampling some of the footprints. People at ancient White Sands usually moved in groups, which often included a mix of ages and genders, based on the other trackways at the site. But for some reason, this person set out alone—almost.

The person’s gait is uneven, as if they were carrying a load on their left hip. And three spots along the northbound trail reveal what that load must have been: a toddler, probably around three years old. The child’s small feet left their own tracks when their guardian set them down just long enough to rest or switch arms.

“It would have been an exhausting walk, and their feet slipped in the mud,” wrote Bournemouth University archaeologist Matthew Bennett and his colleagues in their recent paper. Cleary, this person was desperate and in a hurry, although we don't know why.

Making tracks

Bennett and his colleagues found 427 human footprints preserved in the silt and mud of the salt flats. Based on their size, the prints probably all belonged to the same person (except the few left by the toddler). They record a person walking straight north-northwest, and then back south-southeast, and stepping in a few of the fresh mammoth tracks on the return trip.

Bennett and his colleagues used known ratios between foot length and overall height to estimate how tall the ancient person might have been. Based on the results, the tracks probably belonged to a 12- to 14-year-old child, although it’s possible the track-maker was a very small adult woman. And they set out alone across a landscape on which, as far as we know, people usually stuck together.

This “implies that this journey was perhaps unusual, as does the haste in which it was conducted,” wrote Bennett and his colleagues. Based on stride length and height estimations, the person was walking at a brisk 1.7 meters per second—just this side of breaking into a run on the slick, muddy ground, while carrying a toddler.

But we only get to see the middle of the journey. The tracks found so far don’t include the starting or ending points, although the trail crosses into the adjacent White Sands Missile Range, beyond the reach of the archaeologists. In fact, Bennett and his colleagues had to exclude a few of the prints from the dozens chosen for detailed study because there were missile fragments embedded in them.

Heavy traffic

Despite the questions the tracks can’t answer, they can tell us fascinating things about life in an Ice Age ecosystem and how ancient people interacted with animals that don’t exist anymore. Mammoths and giant ground sloths haven’t walked the Earth for at least 10,000 years, and most of what we know about their behavior is based on their modern relatives. But footprints record snapshots of people and animals actually doing things.

At this particular site, the footprints reveal heavy traffic: massive footprints record at least a dozen mammoths moving from east to west at different times, probably headed toward one of the ponds that formed at low spots in the ancient landscape. The lone teenager carrying the toddler cut across that route at a right angle. At least three times, mammoths crossed the teenager’s trail, obscuring the small human footprints with their own massive feet. The teenager stepped in some of those fresh mammoth tracks on their way back south-southeast.

That’s useful to archaeologists because it tells us that the tracks were made sometime between when humans arrived in New Mexico, roughly 15,000 years ago, and when mammoths went extinct in North America roughly 10,000 years ago. It also tells us that the northbound trail and the southbound trail were made just a few hours or days apart.

The tracks also suggest that mammoths were completely unbothered by the presence of a human nearby. Of the three sets of mammoth tracks that cross the teenager’s trail, none of them suggest that the 6-ton creatures even paused to look around. Either they couldn’t smell the nearby human or they just didn’t care much. Since modern elephants have pretty impressive senses of smell, it’s more likely that the mammoths either didn’t think of people in general as dangerous, or they realized that one small person with a child wasn’t much of a threat.

Giant ground sloths, on the other hand, apparently had more reason to be wary. There’s already evidence that people hunted giant sloths at White Sands during the Pleistocene. When one giant sloth crossed the teenager’s trail, it raised up on its hind legs like a modern bear trying to scout for potential danger. It also did “a circular shuffling dance over the northbound trackway.”

A dangerous journey

As Bennett and his colleagues wrote, “the challenge with any ichnological [footprint] interpretation like this is to find the line between ‘paleo-poetry’ and evidenced fact.”

Mammoths and giant sloths are both herbivores. But just like modern elephants, moose, and bison, they could undoubtedly be deadly if they felt threatened. This would have been a dangerous trip for a person alone, and they were clearly in a hurry. It seems most likely that the person was trying to reach another family or group, and they clearly knew where to go, but we don’t know why. Perhaps the child needed medical care or food that weren’t available elsewhere, or perhaps the teenager’s own group had experienced a disaster of some kind.

There’s at least one more intriguing question. The tracks show us that the teenager was carrying the toddler on their way north; that’s written in the asymmetry of the steps and in the way the northbound tracks show where the person slowed for a few strides before putting the child down for a quick rest. But was the toddler along for the return trip?

The southbound tracks aren’t asymmetrical in the way the northbound tracks are, and there’s no sign of toddler toes or a rest stop along the way. Maybe the teenager reached their destination and dropped the child off somewhere safe, or maybe the child was riding piggyback on the way home. We can only speculate.

Quaternary Science Reviews, 2020 DOI: 10.1016/j.quascirev.2020.106610  (About DOIs).