IUBio Biosequences .. Software .. Molbio soft .. Network News .. FTP

Symbolic Thought (2)

Harry Erwin erwin at trwacs.fp.trw.com
Sun Jul 4 15:11:58 EST 1993

This is the first of three postings that deal with the evolution of
symbolic thought. This one addresses some issues brought up by Jared
Diamond in the Third Chimpanzee (HarperPerennial, 1992).

Symbolic thought appeared about 60000 years ago in Homo sapiens, and is
considered the defining characteristic of modern H. sapiens in the strict
sense (See Stringer and Gamble, In Search of the Neanderthals, Thames and
Hudson, 1993). Diamond speculates that symbolic thought was initially the
result of sexual selection, possibly associated with the "shopping for
genes" strategy, rather than the "shopping for a husband" strategy. It is
well-known that the sexual dimorphism characteristic of modern man
(1.2:1.0 in weight) indicates that we employ a stable polymorphism of
mating strategies. (See Trivers, Social Evolution, for example). Diamond
discusses some evidence that between 10 and 40% of the children born to
married couples were conceived adulterously. These percentages are
consistent with the ratio seen, and with the ratios seen in other primate
species. For example, the pair-bonding marmosets show little or no
dimorphism (as do most pair-bonding birds, see K. Ralls, "Sexual
Dimorphism in Mammals: Avian Models and Unanswered Questions," American
Naturalist, 111:917-938, 1977.), while gorillas have a 2:1 weight ratio
with successful males keeping a harem of 3-6 females.

The questions here are:
1. Is there any evidence that the appearance of symbolic thought is
associated with a change in the degree of sexual dimorphism?

2. Are there estimates available for the degree of sexual dimorphism in
hominid species, including archaic H. sapiens?

For height, data points that I have include:

Modern man--1.08:1
Neanderthal man (Stringer and Gamble, p. 91)--1.05:1

3. When is there evidence for the evolution of the adolescent growth

My take on the evidence so far is that pair-bonding predates symbolic
thought, although, if Diamond is right, symbolic thought evolved through
sexual selection.

Please direct replies to sci.archeology
Harry Erwin
Internet: erwin at trwacs.fp.trw.com
Working on Freeman nets....

More information about the Neur-sci mailing list

Send comments to us at biosci-help [At] net.bio.net