JOHANNESBURG — About 77,000 years ago, in a cave overlooking the Indian Ocean, a group of early people were using bone tools for leatherwork, grinding red ocher into powder, probably for use as body decoration, and even carving geometric designs. At their site, about 150 miles from present-day Cape Town, they used fire contained in small hearths, and hunted a variety of animals and fish.
This small band of early Africans were, a group of scientists excavating the Blombos Cave site believes, thoroughly modern people, capable of abstract thought and probably language. Evidence from their settlement could have important implications for theories about the emergence of modern people.
"The Blombos Cave, along with evidence from other sites elsewhere, is showing us that modern human behavior existed long before we originally thought," says Chris Hensilwood, a researcher at the Iziko Museum of Cape Town and the lead archaeologist at Blombos. "It brings into question the theory that modern human behavior develops late and might really have flourished in Europe only around 35,000 years ago."
For years, many archaeologists believed that abstract thought and sophisticated communication first developed in Europe in a "creative explosion" between 40,000 and 50,000 years ago, sometime after anatomically modern homo sapiens migrated from Africa to Europe and replaced existing Neanderthal populations.
The finds at the Blombos Caves on South Africa's southern coast, however, show that modern human behavior may have first appeared in Africa far earlier.
Among the important finds at Blombos is a large cache of 28 bone tools, which are not usually found in African sites more than 40,000 years old. The site has also yielded 8,000 pieces of ocher, with marks that indicate they might have been ground to make a powder, and evidence of a fishing culture that required sophisticated tools and cooperation. Archaeologists believe the ocher powder was used as a body decoration, a sign of religious or ceremonial beliefs.
Most compelling, however, is the discovery of two small pieces of red ocher, smoothed flat and carved with cross-hatch designs, that may be the earliest pieces of human art ever found.
The creation of art requires abstract thought and is believed to be one of the most important signs of modern behavior. "We don't know what they mean," says Mr. Hensilwood. "But they're very complex designs that are clearly meant to mean something. You see similar designs engraved and painted elsewhere at much later dates."
The search for the origins of modern behavior is one of archaeology's most perplexing puzzles. The key question for scientists is whether modern behavior first began more than 120,000 years ago when humans became anatomically modern, or whether it followed tens of thousands of years later as the result of genetic, environmental, or cultural changes.
The conclusion has important ramifications for understanding human evolution and for theories about the spread of humans from Africa. .
Thirty years ago, scientists drew up criteria for modern behavior. If ancient people could make bone tools, use those tools to fish, and create art, scientists believed they must have had the capacity to reason, organize, and communicate.
While archaeologists generally agree that art indicates the ability for modern thought, there is less consensus on what actually constitutes art. There is a rich collection of European art beginning about 50,000 years ago, which includes elaborate cave paintings, the use of ornaments for personal decoration, and the burial of dead with ceremonial objects.
Among the most spectacular of these finds are the cave paintings in the Grotte Chauvet caves in France, which at 32,000 years old are claimed by the French to be the oldest human art ever found. The paintings are clearly meant to represent living things: lions, rhinos, cave bears, and pregnant women.
While there have been other artistic finds that predate the European art of this period, most have been controversial. In 1980, for example, researchers found a piece of hardened volcanic lava, more than 250,000 years old, that appeared to be engraved with a female figure. While scientists now generally accept that the engravings were intentional, dispute remains about whether they are intentionally representational.
While there has been little debate about the age of the Blombos Cave pieces, some scientists, such as Stanford archaeologist Richard Klein, say they are mere doodles with little or no meaning.
Dr. Klein has long maintained that modern behavior developed between 40,000 and 50,000 years ago as the result of biological or genetic mutation. Although Klein admits there is no fossil evidence indicating a change of this nature, he believes that no other explanation adequately explains the explosion of symbolism in Western Europe after that date. He also says that occasional pieces like the Blombos ocher engravings and similar pieces found elsewhere may simply be aberrations.
Hensilwood, however, believes that even the ability to doodle requires a certain abstract ability. He also argues that because the pieces were found with other artifacts, such as the bone tools, they indicate the existence of a modern society at Blombos.
Hilary Deacon, a professor at the University of Stellenbosch in South Africa, has long argued that early Africans behaved like modern people at least 120,000 years ago. He says the Blombos carvings provide the most incontrovertible evidence yet.
He has long believed that ocher powder was used ornamentally. "If it only has a practical purpose, there's no need to import it in such large quantities," he says.
Archaeologists acknowledge that the African fossil record is thin and more sites need excavation. The debate over Blombos and origins of modern behavior "isn't going to be over any time soon," Hensilwood says.