Going Coastal: Sea cave yields ancient signs of modern behavior

October 17, 2007 at 11:04 am

At Pinnacle Point on South Africa’s southern coast, a cave perched above the sea has provided scientists with evidence of a set of surprisingly complex behaviors practiced by Stone Age people about 164,000 years ago, near the evolutionary dawn of Homo sapiens. Our species emerged an estimated 200,000 years ago.

ANCIENT VIEW The ocean recedes beneath the mouth of a South African cave where researchers found the earliest known evidence of modern-human behavior, including a chunk of pigment (inset). Mossel Bay Archaeology Project

A team led by anthropologist Curtis W. Marean of Arizona State University in Tempe found three critical clues in the cave that point to modern-human behavior: the remains of mussels and other shellfish, 57 pieces of reddish pigment probably used for body coloring or other symbolic acts, and more than 1,800 stone implements, including small, expertly crafted blades.

Ancient Africans took up coastal living between 195,000 and 130,000 years ago, when a relatively cold, dry climate inland reduced the number of edible plants and animals, Marean and his coworkers propose in the Oct. 18 Nature. Shellfish harvested from exposed, rocky shores and from tidal pools offered a stable food source that allowed populations to grow and become less nomadic, in Marean’s view.

Symbolic behavior as a form of social expression could then have flourished, he suggests.

Using modern hunter-gatherer societies as a guide, Marean suspects that coastal living involved a shift from male-dominated big game hunting to female-led foraging for plants and shellfish. “If shellfish were important, it means that women were a key component of that new economy and may have held substantial economic power,” he says.

The earliest previous evidence for shellfish eating and seaside living by modern humans came from a 125,000-year-old East African site.

Pinnacle Point artifacts lay in soil dated by a technique that indicates when sediment was last exposed to light.

Many shellfish remains came from brown mussels, giant periwinkles, and limpets.

Double-edged stone blades appeared in a variety of sizes, including some no more than 10 millimeters wide. Miniature blades could be attached to the end of a stick to form a spear or be lined up like barbs. Comparably small stone blades characterize much younger African sites, beginning about 70,000 years ago.

Pigment chunks included about a dozen that had been ground or scraped. Some also display intentional incisions.

The new discoveries bolster the proposition that modern-human behavior developed gradually, starting perhaps 285,000 years ago, remark anthropologists Sally McBrearty of the University of Connecticut in Storrs and Chris Stringer of the Natural History Museum in London in an accompanying editorial. The earliest evidence of red-pigment use comes from that time, prior to the evolution of anatomically modern humans.

An opposing view holds that a transition to modern-human behavior occurred rapidly around 45,000 years ago.

Complex, symbolic behavior developed differently from one geographic region to another, comments anthropologist Christopher Henshilwood of the University of the Witwatersrand in Johannesburg. Henshilwood has uncovered 70,000-year-old shell beads and pigment pieces in South Africa’s Blombos Cave.

Marean’s finds at Pinnacle Point suggest that an ancient reliance on seafood “may have been one critical factor in the expansion of Homo sapiens out of Africa and along coastal routes to the east,” Henshilwood says.