ON THE BEACH: When the going got tough in ice age Africa, early humans moved to caves on the coast such as this one, at South Africa's Pinnacle Point, where researchers have uncovered the oldest signs yet of seafood meals and symbolic thought. Image: COURTESY OF THE MOSSEL BAY ARCHAEOLOGY PROJECT
When the going got tough, early humans went to the beach for seafood and possibly a dose of symbolic thought, according to a new study. Researchers excavating a cave on the southern coast of South Africa discovered a bowl's worth of edible shellfish dating back to about 165,000 years ago, when Africa was colder and drier—pushing back the earliest known seafood meal by 40,000 years.
The team found small stone blades and reddish rocks tossed in with the shells; the rocks were marked in a way that suggests they were ground into powder used to make paint, possibly to adorn the face or body to symbolize status or membership in a group.
"What we're trying to do is identify the origins of symbolic thought," says paleoanthropologist Curtis Marean of Arizona State University, who led the team.
Researchers believe that anatomically modern humans emerged between 150,000 and 200,000 years ago in eastern Africa. They are less certain about when those humans first developed the potential for symbolic thought, including language. Up for debate: whether modern cognitive abilities occurred gradually or in one fell swoop, perhaps after a sudden structural alteration of the brain.
Looking for early human remains, Marean and his crew homed in on the caves at South Africa's Pinnacle Point. Much of Africa became inhospitable during an ice age that lasted from about 195,000 to 130,000 years ago, leading to cold, dry conditions on the continent that forced at least some humans to the coast. Many coastal caves were cleaned out when sea levels later rose, but Pinnacle Point stayed high and dry.
The researchers report in Nature that they uncovered two dozen shells of edible creatures from a layer of cave sediment that dated to 164,000 years ago, give or take 12,000 years. Brown mussels were the main component—and are still plentiful—Marean says. "I have to avoid walking on them when I'm working on the rocks out here," he notes. "At low tide, you can dip your hand under the water and oysters are right there."
The shells also included at least one barnacle that lived on whales, the team reports, suggesting that the inhabitants scavenged blubber from whales that washed ashore.
The next earliest known seafood dinner dates to 125,000 years ago on the coast of the Red Sea in Eritrea. And, about 110,000 years ago, Neandertals were cooking shellfish in caves in coastal Italy.
The researchers identified 57 pieces of iron-rich hematite rock with flattened sides bearing parallel grooves, indicating that the shellfish-eaters scraped the rocks to make powder, which when mixed with sap or another binder yields a reddish or pinkish paint.
"We've shown pretty strongly that people [were] working with pigments [164,000 years ago], which is a pretty good indicator of symbolic thought," Marean says. A population living on shellfish would have stayed in one place and grown in number, he says, increasing the need for negotiations between individuals or social groups, which might have led to a system of decorative markings.
"One could argue that we had cognitively modern humans around for a long time," he says. "Then you get this harsh environment that provides a context where all of a sudden their abilities to 'symbol' [or symbolize] are tapped. I think that's very likely."
Other sites have turned up shell beads dating to at least 100,000 years ago in Israel and evidence of pigment use 120,000 years ago in South Africa.
Pigment rocks were not necessarily used for symbolic purposes; they could also have netted a kind of glue for constructing tools, says Alison Brooks, a specialist in later human evolution and professor of anthropology at The George Washington University in Washington, D.C., who has argued for the gradual emergence of modern cognitive abilities.
She says the findings indicate that "whatever people were doing at 120,000 years, they seem to also have been doing at 160,000 years," suggesting that, as far as cognitive potential went, there was "no magic, instant revolution."