The versatility that helped humans take over the world emerged very early in our evolutionary history, according to sediments and stone tools from Olduvai Gorge in Tanzania.

Olduvai has provided some of the oldest known tools and fossils from our genus, Homo . A recent study lines that evidence up with environmental clues buried in the sediment. The results suggest that our early relatives were equipped to adapt to new environments by around 2 million years ago.

That seems to have been a key ability that allowed our relatives to go global. By 1.7 million years ago, an early human relative called Homo erectus had spread beyond Africa and throughout most of Asia, as far as Indonesia. They had reached western Europe by 1.2 million years ago. Along their travels, the hominins encountered environments very different from the ones their ancestors had evolved in, like the tropical forests of Indonesia and the arid steppes of central Asia.

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Fragments of glassy petrified grass and microscopic traces of plant material, dating to around 200,000 years ago, are all that’s left of a Paleolithic hunter-gatherer’s bed in the back of Border Cave. In the same part of the rock shelter, archaeologists found layers of ash with more recent (as in only around 43,000 years old) and better-preserved leaves of dried grass laid on top, as if people had burned their old, dirty bedding and then laid fresh, clean sheaves of grass over the ashes—the rock shelter version of changing the sheets.

The finds shed light on an aspect of early human life that we rarely get to consider. Most of the artifacts that survive from more than a few thousand years ago are made of stone and bone; even wooden tools are rare. That means we tend to think of the Paleolithic in terms of hard, sharp stone tools and the bones of butchered animals. Through that lens, life looks very harsh—perhaps even harsher than it really was. Most of the human experience is missing from the archaeological record, including creature comforts like soft, clean beds.

Beds were burning

Until now, the oldest bedding archaeologists had ever found came from another South African site called Sibudu, where people 77,000 years ago had piled up layers of grasslike wetland plants called sedge, mixed with assorted medicinal plants, and occasionally burned the old layers. Some modern people in parts of Africa also use plants as bedding in similar ways. The Border Cave find shows that people have been making comfy sleeping pallets out of grass for at least 200,000 years—nearly as long as there have been Homo sapiens in the world.