Small oval depressions—376 in all—are scattered across a patch of dry ground nestled between the dunes of northern Saudi Arabia. At a glance, these pockmarks don't seem particularly impressive, so much so that a team of scientists surveying the region almost passed them by in 2017. But upon further examination, the team realized that the depressions were left by an array of ancient animals, and among them were traces of our own species, Homo sapiens.

The discovery of human footprints, if confirmed, would mark the oldest trace of our species yet found in the Arabian Peninsula, which sits at the gateway to early humans’ spread around the world. As described in a new study published in Science Advances, the frozen