Our ancestors had a bash eating wild nuts. (Almond Joy, Stone Age Style).

Around 780,000 years ago, human ancestors living along a lakeshore in what is now northern Israel ate a varied diet. It included fat- and protein-rich almonds, pistachios, and other hard-shelled nuts, according to a new report.

As both chimpanzees and many hunter-gatherer groups of people do today, inhabitants of the ancient site used pieces of stone to crack open these nutty treats, say archaeologist Naama Goren-Inbar of Hebrew University of Jerusalem and her colleagues.

Their new findings appear in the Feb. 19 Proceedings of the National Academy of Sciences.

Evidence gathered from this location, called Gesher Benot Ya'aqov, indicates that it served as a base camp from which members of a still-undetermined Homo species launched foraging and hunting expeditions, Goren-Inbar argues. "An extensive array of activities involving both men and women occurred there," she says.

The theory that ancient humans typically operated out of base camps as early as 2 million years ago, first proposed in 1977, has drawn criticism from researchers who say that life at that time was fundamentally nomadic. The new evidence from Gesher Benot Ya'aqov indicates that home bases existed nearly 800,000 years ago.

The site's waterlogged sediment has preserved artifacts much better than has dry soil at most other sites of comparable age. As a result, Goren-Inbar's group was able to find seeds and other remains from seven species of edible nuts. Four of the nut species--acorns, almonds, pistachios, and the water chestnut--have hard outer shells that must be cracked open before eating.

The researchers also unearthed 54 stone implements bearing surface depressions produced by some type of repetitive pounding. The size, shape, and texture of these marks closely resemble pitting on nut-cracking stones used by chimps and modern hunter-gatherers, the researchers assert. Small nut-cracking stones at the site served as hammers, whereas larger ones were used as anvils, according to the scientists.

Stone artifacts previously identified at a few other sites, such as 1-million-year-old finds from Tanzania's Olduvai Gorge, display small pits on their surfaces. However, these marks have usually been attributed to the stones' having been used to make or modify other stone implements.

Goren-Inbar's group considers tool production an unlikely explanation for its new discoveries. The Israeli site's stones bear deeper, rounder, and smoother pits than those on similar implements the scientists fashioned in stone-toolmaking experiments.

Goren-Inbar proposes that females at the camp probably took charge of gathering nuts and preparing them for eating, as females in chimp and hunter-gatherer groups are known to do. Males, on the other hand, probably assumed greater responsibility for hunting and butchery, activities for which much fossil evidence exists at the Israeli site, she adds.

Because Olduvai Gorge sites lack preserved plant and seed remains, it is difficult to know how pitting occurred on implements found there, Goren-Inbar says. Still, nuts' dietary prominence among African groups today suggests that "if nuts were available in ancient Olduvai, [human ancestors] probably gathered and consumed them," she theorizes.

The range of activities now indicated at Gesher Benot Ya'aqov indicates that it was a residential hub with access to nearby water and food resources, in Goren-Inbar's view.

"The preservation of artifacts at [the site] is much better than at any other site of that time," comments archaeologist Ofer Bar-Yosef of Harvard University. "It makes sense that this site was used as a home base at that point in the Stone Age."