- The ornamental shells and rabbit-hunting of prehistoric
peoples are shedding new light on the great debate over the origin of modern
humans.
Recent discoveries of similarly-aged adornments and changes in hunting
practices at widely dispersed sites across Europe and Asia suggests that
these modern human behaviours arose simultaneously in many places.
This provides evidence for the "continuity" theory of modern
human development, i.e. that development occurred in parallel in different
populations across the world. The alternative "out of Africa"
theory suggests that an exodus from that continent about 50,000 years ago
swept across the world, driving indigenous populations to extinction.
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- Ornament shells from Turkey Photo: H. Stiner
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- Mary Stiner, from the University of Arizona, told the
American Association for the Advancement of Science's annual conference
that the earliest examples of adornment occur close in time in at least
four different places. Stiner's own work has uncovered shells in Turkey
that were punctured in a deliberate way between 40,000 and 45,000 years
ago.
These holes, for stringing the beads, could not have been made by accident
or by predatory molluscs, she says. Contemporaneous finds of ostrich eggshell
beads have also been made in Kenya, and other adornments have been unearthed
in Lebanon and Bulgaria.
- Tortoises and hares
- Further work by Stiner and colleague Steven Kuhn in several
Upper Paleolithic sites around the Mediterranean has revealed a change
in the prey hunted by early humans in the east about 40,000 to 50,000 years
ago. Stiner says there are also early indications of similar changes in
Africa.
Their analysis showed a significant shift from slow-reproducing and easy-to-catch
animals like shellfish and tortoises, to quickly-reproducing and more agile
animals like partridges, hares, and rabbits. The reason for the shift is
likely to be an increased pressure on resources, Stiner says: "If
you have over-used your preferred resource, you can respond by turning
to lower-ranked, harder-to-catch resources."
An increasing population may also explain the use of adornments, due to
the increased need to communicate with each other. "Ornamentation
is universal among all modern human foragers," says Stiner, noting
that these groups use the ornaments to convey information about kinship
and status to outsiders.
- Fossils and genes
- The timing of these two behavioral changes, long after
the first appearance of anatomically modern humans in the fossil record,
"makes it clear that modern human behavior doesn't appear at the same
time that skeletally modern humans do," Stiner concludes.
She believes archaeology has some key advantages over other approaches
in studying the rise of early humans: "The nice thing about archaeology,
something that's missing from fossil and genetic data, is that we have
a fairly refined level of detail on the age and geographic location of
our evidence."
Archaeologist Lawrence Straus, from the University of New Mexico, agrees
the evidence supports the continuity theory: "The ongoing process
of human adaptation was a long, drawn out process, mosaic in nature. The
idea of a total and abrupt replacement of an inferior species 40,000 years
ago has in my opinion been fabricated."
- Damian Carrington, Boston
http://www.newscientist.com/news/news.jsp?id=ns99991938
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