Ancient bone tools and spear points found in cliff-side caves
along South Africa's coast appear to be turning back the clock on
the emergence of modern human behavior.
In research released here this week, an international team of
archaeologists and anthropologists exploring a site called the
Blombos Cave described finding tools and large amounts of ochre
encased in sandy deposits at least 70,000 years old. Ochre is a
mineral widely used as a pigment to adorn bodies and clothing.
An ability to craft and in some cases polish "formal" tools, and
the use of symbols, implied by the presence of ochre, are among the
behaviors that separate humans from their primate relatives, notes
Curtis Marean, an Arizona State University anthropologist and a
member of the team that made the discovery.
If the artifacts themselves match the age of the deposits that
harbored them, as expected, it could begin to shift the center of
gravity for studying the evolution of human behavior from Europe to
Until now, sites on the European continent dating back some
40,000 years have set the benchmark for tracking the evolution of
"behavioral modernity" in humans, who are thought to have expanded
out of Africa some 50,000 years ago.
"We are at the frontier of discovery," Dr. Marean said at a
series of briefings at the Council for the Advancement of Science
Writing in Phoenix. As more evidence emerges from the Blombos site
and a growing number of other locations in the region, "I think we
are going to find that the pattern is conclusive."
If such a pattern emerges, it could begin to quell a longstanding
debate over whether modern human behavior evolved as humans did
physically, or whether it began to take shape long afterward.
Although physically, modern humans appeared some 100,000 to 150,000
years ago, many have held that modern human behavior only emerged
within the past 40,000 years.
The debate has been fueled by the fossil record from this period.
That record is rich in Europe, which boasts some 200 to 250 well-
excavated sites, Marean says. Until now, the African record has been
at best ambiguous. Thus, the timetable for the evolution of human
behavior has been based largely on European evidence, he notes.
Europe has a wealth of limestone formations that have caves early
people used for shelter. Those caves also helped protect and even
fossilize the remains of early inhabitants. …