First of all, language (or the invention of language) does not enter into any discussion of biological evolution, because biologically modern humans (i.e., humans whose biological development had ceased) preceded by some more or less long period the 'invention' of language.
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CB: I don't think this is true. Ability to symbol/language defines the species human.
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(I keep coming across quite different estimates of how far back _homo sapiens_ goes. But 100,000 years is one estimate one often finds. One very prominent anthropologist suggests that language did not appear until about 40,000 BP. (See Ian Tattersall, _The Monkey in the Mirror: Essays on the Science of What Makes Us Human_ [2002] and _Becoming Human: Evolution and Human Uniqueness_ [1998]).
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CB: I think Sahlins, Geertz, Kottak, Harris, et al. disagree with this. When I was an undergrad anthro major, homo sapiens was estimated to arise 40,000 years ago. Since then they have been moving it back. But part of the basis for designating early finds as human is inference that language/symbolling is associated with the fossils.
Again, language/symbolling is a definitional trait of homo sapiens.
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He speculates that _children_ invented languages, and speculates further that they did so several times before adults 'caught on.' He has some interesting material on amonkey 'tribe' in which the young monkeys began to wash the beach sand off their food, the practice then being adopted by older females, but _never_ adopted by the older males.
^^^^^^ CB: Interesting.
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>From what I've gathered from various writings I've come across, a good deal
of what we think of as distinctively human lies in traits which are
spandrels -- i.e. traits which had no practical use when they first evolved
(and hence were not subject to adaptation) but which simply were 'by-blows'
of other traits which did have adaptive worth.
^^^^ CB: What traits ? Upright posture ? Opposable thumb ? Big skulls ? Teeth ?
This spandrel logic is not clear. Language, whether somehow first arising as a byproduct of something else, _is selected for at once when arises_ because it gives adaptive advantage. How is it adaptive ? It enormously enhances sociality. We might say enhanced sociality, including intergenerational communication, is a "spandrel" of language, but that's a fuzzy argument. Easier to just say enhanced sociality is selected for , once it arises, regardless of the fact that it is a byproduct of language/symbolling.
As soon as language/symbolling arises it is immediately an adaptive advantage. No time to be a spandrel.
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ALSO. See Oliver Sacks in a recent NLRB. It has been pretty well established by recent studies of brain-damaged patients that complex thought is possible (and occurs) in those who cannot understand, create, or think in words. Further, mathematical ability is sharply separated from language. It would, that is, have been quite possible for humans to flourish for 10s of thousands of years without language.
^^^^ CB: They wouldn't be humans. Of course, species can flourish for tens of thousands of years , millions, without language. All the prehuman species flourished for eons without language.
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Language ability is almost certainly a spandrel. Also, we simply don't know how far back 'symbolling' goes; there is no evidence for it before about 40,000 BP, but there is no evidence against it either.
Carrol
^^^^^ CB:
Language would be immediately and inherently an adaptive advantage. It enhances sociality enormously. The great human adaptive advantage is greater sociality.