ALCANENA, Portugal — Deep inside a limestone hill in central Portugal, in a chamber no larger than a living room, a group of children once ran across a floor of wet clay. Their footprints — 38 of them, the smallest barely 14 centimeters long — survived because a trickle of mineral-rich water later sealed them under a thin, glassy crust.
On Friday, a team of Portuguese and German researchers reported that the prints were made by Neanderthals roughly 112,000 years ago, and that most of them belonged to children between the ages of about 3 and 7. The study, published in the journal Nature Ecology & Evolution, describes what the authors call “the clearest record yet of Neanderthal children at play.”
“You can see them running, you can see one child slide and land on both feet,” said Mariana Castelo Branco, an archaeologist at the University of Coimbra who led the excavation at the Gruta da Lapa Fria. “There is no tool, no fire, no animal bone in that chamber. It is a space where small people moved around for fun.”
The cave was found in 2021 by quarry workers and sealed off while the team mapped it. The prints were dated with uranium-thorium analysis of the calcite crust, which gave an age of between 108,000 and 116,000 years — a period when Neanderthals were the only humans in Western Europe. Three larger prints, about 26 centimeters long, suggest at least one adult stood near the chamber entrance.
Henrik Vollmer, a paleoanthropologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig and a co-author, said the find adds to a growing body of evidence that Neanderthal childhood looked much like that of early modern humans. “We have long known they cared for the injured and buried the dead,” he said. “What this adds is ordinary life. Children being children.”
The team used photogrammetry to build a millimeter-scale model of the floor, then compared stride length and foot proportions with data from modern children. Two tracks cross each other at a run, and one short sequence shows a child stepping up onto a ledge and dropping back down, at least twice.
Not everyone is persuaded by the playful reading. Agnieszka Dobrowolska, a paleoanthropologist at the University of Warsaw who was not involved in the work, called the prints “superb” but cautioned against inferring motive. “Children also run when they are frightened,” she said. “The honest version is that we have children moving quickly in a dark place. Why is a story we tell.”
Dr. Castelo Branco said the chamber will remain closed and climate-controlled; visitors to the regional museum in Alcanena will see a full-size 3D print instead. “The children have kept their floor for 112,000 years,” she said. “We are not going to be the ones who ruin it.”
A version of this article appears in print on Oct. 11, 2026, Section A, Page 12 of the European edition with the headline: In a Portuguese Cave, Footprints Suggest Neanderthal Children Played in the Mud.
