Saturday, March 20, 2010

Self Domestication Of Humans And Symbolic Language

There are topics I like to read about and I think I am understanding the subject matter as I read along. But if asked to explain that to someone else.. I would probably draw a blank.

The evolution of language is a fascinating topic and on NPR's Cosmos and Culture blog language experts Terrence Deacon and Ursula Goodenough write a post on the evolution of symbolic language in humans:

The world of symbols is an artificial niche, its ecology radically different from the biological niche we also occupy. In the same way that beaver dam-building has created an aquatic niche to which beaver bodies and behavior have adapted over their evolutionary history, our cognitive capacities have adapted to our self-constructed symbolic niche.

..and this very interesting take on how domestication or rather establishment of a particular social and cultural niche in early human societies may have prodded the evolution of complex language:

Recent investigations of birdsong offer some clues in thinking about language evolution.

As expanded in an earlier blog, a comparative study of a recently domesticated bird and its feral cousin revealed that the domesticated lineage is a far more facile song-learner, with a much more complex and flexible song, despite the fact that the domesticated bird was bred for plumage coloration, not singing.

That this behavioral and neural complexity arose spontaneously was surprising given the common assumption that song complexity evolves under the influence of intense sexual selection, which was not operant under the breeding regime. One intriguing interpretation is that the relaxation of natural and sexual selection on singing was in fact responsible for its complexification. With song becoming irrelevant to species identification, territorial defense, mate attraction, predator avoidance, and so on, degrading mutations and existing deleterious alleles affecting the specification of the stereotypic song would not have been weeded out, the result being a reduction in the innate biases controlling song production. With specification of song structure no longer strictly controlled by the primary forebrain motor center, auditory experience, social context, learning biases, and attentional factors could all begin to influence singing, the result being that the domestic song became more variable, more complicated, and more influenced by social experience.

Relaxation of selection may have led to phenotypic plasticity - in this case an increased repertoire of behavioral /audio responses - being tolerated and eventually the genetic basis for this increased range was positively selected for over evolutionary time and became an adaptive feature.  I think this is called genetic assimilation or the Waddington effect.

I may be wrong about this being an example of genetic assimilation... any case the article is worth reading.

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