Monogenesis and "simple Darwinian grounds"

[Scott DeLancey]

----------------------------Original message----------------------------
On Thu, 29 Jan 1998, Richard Janda wrote:
 
>   While agreeing with most of Scott DeLancey's last posting, I believe that
> it is a demonstrable fallacy to claim that, "on simple Darwinian grounds",
> "monogenesis has to be correct".
 
Well, I can't agree with some of your points.  In particular:
 
> terizing the ultimate ancestor of some language family.  That is, even as-
> suming that, due to selection, some mutation which provided the prerequisites
> for language came to characterize all living humans at some point, it does
> not follow that there was only one occasion on which sound/meaning associa-
> tions were arrived at and then passed on to succeeding generations.  Rather,
> a language-facilitating mutation could have been selected for but then not
> immediately acted on, as it were (and this does not strike me as unlikely).
 
This is not only unlikely, it's not even coherent.  How can something be
selected for without being "acted on"?  Selection isn't an abstract
intellectual exercise; it's a label for the fact that some individuals
reproduce more successfully than others, so that their genetic endowment
is disproportionately represented in succeeding generations.  Selection
in connection with a particular trait occurs because that trait leads
to differential reproductive success.  Thus a trait can only be selected
for (or against) if it is manifesting itself in the individuals carrying
it.
     But I had in mind a different Darwinian argument.  Richard says:
 
> It hardly strains credulity to imagine that two groups of early humans living
> widely separated from each other could independently have stumbled onto the
> use of sound/meaning associations for communication in specifically linguistic
> ways.
 
It may not strain credulity, but it's vanishingly unlikely.  Once one
population has developed an advantageous trait, it will then out-reproduce
competing populations which lack that trait, and eventually replace them.
Once one population has developed language, it's not likely that anyone
else will get the chance.  I'm no archeologist, but I understand that
the archeological record suggests an explosively fast expansion of
modern humans (at the expense of Neanderthals).  The obvious inference
is that a single population developed language, giving it a selectional
advantage which allowed it to overspread the world very quickly.
 
Scott DeLancey
Department of Linguistics
University of Oregon
Eugene, OR 97403, USA
 
delancey at darkwing.uoregon.edu
http://www.uoregon.edu/~delancey/prohp.html