It may look like a bagel, but this is actually a bead made from an ostrich shell overlaid on images of where it came from and where it was found. Brian A. Stewart, Yuchao Zhao, and the University of Michigan Museum of Anthropological Archaeology/John Klausmeyer

Stone age communities were bound together by gifts that traveled far beyond the orbit of the maker, reaching locations the giver might never see. The networks these gifts trace provided a support system that helped our ancestors survive times of hardship, letting them know they were not alone and could call on others in their hour of need.

Hunter-gatherers around the world have systems, known as delayed reciprocity, to support those suffering temporary deprivation. The most studied is that of the Ju/’hoãn people of the Kalahari Desert, who use gifts to cement these bonds, passing on symbolic objects to those they may rely on in the future. This is a place where humanity has lived for hundreds of thousands of years, leading anthropologists to wonder if these practices are of similar age. We don't yet have an answer to that, but Dr Brian Stewart of the University of Michigan has found evidence people nearby were doing similar things 33,000 years ago.

Stewart's claim is based on analysis of numerous beads, once part of necklaces, found in Lesotho, a mountainous nation surrounded by South Africa. The beads, like millions of similar ornaments in Africa's long human habitation, are made from ostrich shells. When Stewart studied the shell's composition, he found more than 80 percent contained strontium isotopic ratios, indicating the bird that laid them fed far away, probably in the Karoo desert on the other side of southern Africa.

Map of Southern African rock types, showing where the beads were found and the distances that must have been traveled to from where they could have come. PNAS/Stewart et al.

In Proceedings of the National Academy of Sciences, Stewart and co-authors argue the beads are evidence, not of trading but of a chain of gift-giving that stretched for hundreds of kilometers.

"Humans are just outlandishly social animals, and that goes back to these deep forces that selected for maximizing information, information that would have been useful for living in a hunter-gatherer society 30,000 years ago and earlier," Stewart said in a statement. "Ostrich eggshell beads and the jewelry made from them basically acted like Stone Age versions of Facebook or Twitter 'likes,' simultaneously affirming connections to exchange partners while alerting others to the status of those relationships."

Lesotho's high altitude made it a difficult place for people to live, particularly through an ice age winter. However, its abundant rainfall meant food could still be found there when drought gripped the lowlands. The paper credits the transfer of gifts like ostrich shell necklaces with humanity's “release from proximity”, allowing humans to build support and information networks that helped make us who we are. Today, Ju/’hoãn communities will exchange gifts with others more than 50 kilometers (30 miles) away, establishing a connection that will provide sanctuary in the face of a local disaster.