July 7, 1998 CHAMPAIGN, Ill. -- Excavations from the Enkapune Ya Muto (EYM) rock shelter in the central Rift Valley of Kenya offer the best evidence yet that modern human behavior originated in Africa more than 40,000 years ago. They also suggest that by that time our earlier selves sealed social alliances and prevailed over others by giving token gifts, in this case, beads. So says archaeologist Stanley Ambrose, a professor at the University of Illinois.
Ambrose, an expert on stone tools, paleoecology and stable isotope biogeochemistry, has found that his EYM site "contains perhaps the earliest example of what we think of as an Upper Paleolithic stone-tool technology, and then later in time, ostrich eggshell-bead technology -- the earliest evidence for ornamentation, which may imply a new kind of adaptive social system."
In one of the oldest layers, Ambrose found the stone tools -- "possibly the oldest example of Later Stone Age or European equivalent Upper Paleolithic stone-tool technology. The blade-based tools are at least 46,000 years old, but may be as much as 50,000 years old -- older than the oldest previously known industry of its kind, from Israel."
Above the earliest Later Stone Age stone tools, he found the beads. Dated by radiocarbon to about 40,000 years ago, the beads "are the oldest directly dated ornaments in the world," Ambrose said. Ornaments are widely considered an important class of evidence for modern human behavior. Moreover, among modern hunter-gatherers, the beads are not only used as ornaments, but are the most common kind of gift in a formal system of delayed reciprocity, which has further implications for the evolution of a social safety-net system."
It has been argued, Ambrose said, that human adaptability to risky environments involves "being able to have relationships with people that you can rely on when resources in your area fail."
"The ancient beads may thus symbolize a mechanism for increased social solidarity and adaptations to risky environments. They may be a symbolic currency for exchange and obligations that can be saved for times of need -- like money in the bank. People who have this social security system would compete better with others -- the Neanderthals, for example -- who didn't. So, this improved system of regional networks of social solidarity may have allowed modern humans, when they left Africa, to outcompete and replace the Neanderthals."
The evidence of exchange networks is the long-distance movement of materials over distances greater than a band of hunter-gatherers might move over the course of a year, Ambrose said, "So, you find shells in Upper Paleolithic Europe moving as much as 600 kilometers."
"This site seems to provide dating evidence that the transition to modern human behavior and technology occurred earliest in East or Equatorial Africa and spread from there."
Ambrose's findings appeared in the April issue of the Journal of Archaeological Science.
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