Dear Marcello (and dear All),
I have a few comments/questions to your text (though I have little or nothing to contribute with concerning a general discussion about biolinguistics). First, though, I would like to ask where it will be published (as I would like to quote it in one of my articles-in-process).
Now, to questions and comments:
1) You write that "Sebeok’s conclusion that semiosis is based on interpretation is undoubtedly valid in animals, but ... not applicable, for example, to the cell, where the genetic code has been virtually the same for billions of years, which clearly shows that it does not depend on interpretation." It is not clear to me how the fact that the genetic code has been virtually the same practically forever shows that it does not depend on interpretation, since in order to function the genetic code must not only have been encoded but must further repeatedly be decoded - at a cellular level (and herein lies interpretation).
2) You claim that "animals do not interpret the world but only representations of the world. Any interpretation, in short, is always exercised on internal models of the environment, never on the environment itself". Sure, perception of "external reality" is always mediated. Nevertheless, "the environment" (in an objective sense) necessarily represents the final/ultimate object of any perception. The percepts are never identical to their final objects - but why stress that they are (fundamentally) different from them? That is trivially true. But related they are. Not even man can take in "reality" unmediated.
3) I find your explanations of how natural selection favors icons and indexes rewarding and interesting - but when you ask: "Why were animals unable to go beyond icons and indexes? Why didn’t they learn to use symbols?" I think you neglect some empirical evidence to the contrary.
4) I also found interesting your observation that in "all other mammals the wiring of the brain takes place almost completely in the dark and protected environment of the uterus, whereas in our species it takes place predominantly outside the uterus, where the body is exposed to the lights, the sounds and the smells of a constantly changing environment." This is clearly a key point.
I have followed this discussion throughout, and realized how frustrating it must have been for you to see how few actually addressed the (new) substance of your article. That was a shame. Hopefully the ideas concerning the origin of language herein will be analysed in much more detail (from both sides of the fence) after your article has been published.