Living in a cave may not be luxurious, but the ancient inhabitants of southern Africa did their best to make their homes as snug as possible by creating soft beds out of ash and grass. According to a new study in the journal Science, this mixture allowed for a good night’s sleep as it provided soft bedding while also helping to repel insects, and was already in use some 200,000 years ago.

Previously, the oldest known use of plant bedding was from a 77,000-year-old site called Sibudu in South Africa, where researchers discovered layers of sedge interspersed with ash and medicinal plants that they believe were used as rudimentary mattresses. Yet this latest finding pushes back the date of the earliest use of bedding by over 100,000 years.

The discovery was made in Border Cave, which is also located in South Africa and is known to have been occupied intermittently from about 227,000 years ago. Using a range of microscopic and spectroscopic techniques, the study authors were able to identify grass in a layer of white ash that has been dated back to the cave’s early years of human occupation.

In their write-up, the researchers claim that the material was discovered in a part of the cave that would most likely have been used for sleeping, and that the ash would have repelled insects as it prevents them from crawling, blocks their biting apparatus, and dehydrates them.

This theory is supported by the fact that the researchers were able to identify the remains of camphor leaves among the bedding. Given that this aromatic plant is still used as an insect repellent in East African bedding to this day, the study authors are fairly confident that Border Cave’s earliest tenants were indeed using plants to create comfortable, bug-free sleeping spaces.

While the act of collecting soft leaves to sleep on may not seem all that impressive, the kind of cognitive complexity that is required for this sort of innovation is generally thought to have developed in humans about 100,000 years ago. That this discovery significantly predates that threshold suggests that the potential for a sophisticated material culture was very much present at the dawn of man.