Science Magazine

"Early to bed and early to rise, makes a man healthy, wealthy, and wise," wrote Benjamin Franklin in his Poor Richard's Almanack.

Early members of our species, Homo sapiens, were nomads who made their living by hunting and gathering. Yet they often created temporary base camps where they cooked food and spent the night. One of the best studied of these camps is Sibudu Cave, a rock shelter in a cliff face above South Africa's Tongati River, about 40 kilometers north of Durban. Sibudu was first occupied by modern humans at least 77,000 years ago and continued to serve as a favored gathering place over the following 40,000 years. Since 1998, a team led by Lyn Wadley, an archaeologist at the University of the Witwatersrand, Johannesburg, has been excavating at Sibudu, uncovering evidence for complex behaviors, including the earliest known use of bows and arrows.

Over the past several years, the team has found that many of the archaeological layers featured large, 1-centimeter thick swaths of plant remains, including the remnants of both stems and leaves. Most of them cover at least three square meters. The team suspected that these swaths were the remains of bedding, but the earliest previous evidence for sleeping mats is only between 20,000 and 30,000 years old, at sites in Spain, South Africa, and Israel, where similar but more fragmentary arrangements of plant remains have been found.

So to be sure, the researchers put the remains under the microscope. Reporting online today in Science, Wadley and her colleagues describe the results of two sophisticated archaeological techniques: analysis of phytoliths, tiny fossil plant remains, which allows identification of plant species; and micromorphology, the high-resolution examination of archaeological remains.

The team found that the swaths, which dated from 77,000 to 58,000 years ago, were made from sedges, rushes, and grasses, plants that grow down by the Tongati River but are not found in the dry rock shelter. Thus the people at Sibudu must have gathered them deliberately and brought them to the cave. Under the microscope, blocks of the plant material showed signs of compression and repeated trampling. In the earliest layer, 77,000 years old, the team found the leaves of Cryptocarya woodii, also known as Cape laurel, or the "bastard camphor tree," an aromatic plant whose leaves are used in traditional medicines even today. The leaves contain several chemical compounds that can kill insects, and the team suggests that early humans chose them to protect against malaria-carrying mosquitoes and other pests.

Microscopic analysis also suggests that the bedding had been burned, perhaps to eliminate insect pests and get rid of accumulated garbage, so that new layers of bedding could be laid down.

To bolster its case that the plant remains represented bedding, the team members practiced a little experimental archaeology: They collected sedge plants, allowed them to dry, cut them into sections, then layered them in a hole dug in some sand. They compacted the plant mats with a tennis court roller, ignited them and let them burn, and then compacted them some more. The resulting compressed layers looked very similar to the ancient samples found at Sibudu, the team reports.

Despite this evidence that modern humans made themselves as comfortable as possible at Sibudu, Wadley doesn't think they stayed there long. "It is unlikely that the site was occupied for more than a few weeks at a single stretch," she says, citing analogies from modern hunter-gatherers. "The rock shelter would have been abandoned when food supplies became low, or when the site became unpleasant to live in because it smelled bad, had lots of decaying organic material, or was overrun with pests such as insects or rodents."

Dolores Piperno, a phytolith expert at the Smithsonian Institution in Washington, D.C., thinks that the team's claim is sound. "Their evidence is persuasive, and the work is well-done," Piperno says. And Wendy Matthews, an archaeologist and micromorphology expert at the University of Reading in the United Kingdom, praises the team's experiments but questions whether they used enough plant material to reliably recreate these first mattresses.

Among the plant remains, Wadley's team also found tiny fragments of chipped stone and crushed, burnt bone, which the researchers interpret as evidence that these were not only sleeping mats but also work surfaces where tools were fashioned and food was prepared. Thus while early modern humans were skilled at organizing their living spaces, some parts of the cave served double duty, Wadley says. "There were no rules for separate eating, working, or sleeping places," she says. "Breakfast in bed may have been an almost daily occurrence."

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