This is the second of three postings on the evolution of symbolic thought.
Following Stringer and Gamble (In Search of the Neanderthals, Thames and
Hudson, 1993), symbolic thought is associated with the following:
1. long-range planning,
2. spacial organization of living spaces,
3. evidence for advanced language,
5. exchange, and
6. long-range migrations.
Archaic populations with no evidence for symbolic thought (Neanderthals,
H. sapiens prior to about 60,000 years ago) probably had the following:
1. planning horizons of days or weeks,
2. lack of spacially organized living spaces,
3. no art, exchange, or long-range migrations,
4. limited innovation,
5. less advanced language, and
6. little or no post-reproductive survival.
Archaic populations were characterized by the following:
1. Blade tools (both Pre-Upper Paleolithic and Chatel-Perronian),
2. Care for the aged and infirm,
3. Some innovation and adaption of culture to the landscape,
4. Burial practices, and
5. Complex social interactions.
The first evidence for symbolic thought is the sea-borne invasions of
Australia, Papua-New Guinea, and the Solomons Islands about 55,000 years
ago. This suggests that symbolic thought evolved in Southern Asia shortly
before. Jared Diamond (The Third Chimpanzee, HarperPerennial, 1992)
suggests that it was the result of sexual selection (male and female
choice). It appears to have evolved in a species that was fully modern
except for the lack of evidence for symbolic thought. This population
appears to have been tropical in origin (Cro Magnon man was probably black
or dark-skinned, while Neanderthal man was probably very light-skinned).
There is evidence that modern H. sapiens requires a population of at least
5000 to retain technology. Smaller populations gradually lose culture and
eventually become extinct. This seems to be associated with the
post-reproductive survival and possibly with the extended infancy/child-
hood/adolescence of modern H. sapiens individuals. The pattern of non-
symbolic thought seen in archaic populations over at least 170,000 years
implies that either:
1. symbolic thought evolved suddenly with no intermediate stages (highly
unlikely based on work done by the author), or
2. there was a change in the selective pressures on some population
that began to favor symbolic thought.
There are a number of ways a change could have occurred, including:
1. Sexual selection (Diamond),
2. An environmental change that reduced the selective barrier to
symbolic thought by allowing slower maturation and less pressure
on adult survival, (probably an element)
3. A local density fluctuation in the population established a
interbreeding community of archaic H. sapiens that was sufficiently
large that technology innovation could occur faster than technology
was lost. This would then favor innovative individuals. (dubious)
In any case, the selective advantage of symbolic thought is dependent on
the existance of a community that can transmit and share symbolic
paradigms. (Remember, symbolic thought had reduced fitness in archaic
Internet: erwin at trwacs.fp.trw.com
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