Lucas proposes that we wait for consensus about what questions to ask, but I suggest that it is better to ask too many questions than too few. If there are other prerequisites for language than those I propose, let us ask about them as well. Prudkov develops his own theory and makes only passing reference to my target article.
2. The only alternative prerequisite that Lucas suggests is mimesis. She cites Donald (1991) who, she says, "suggests that mimesis, not imitation, was the essential precursor to naming". As Donald describes mimesis, it was a means by which behavior was coordinated, and it required imitation. I do not see mimesis and imitation as mutually exclusive alternatives, as Lucas apparently does, but as different names for the same or, at least, overlapping concepts. For Donald, "mimesis" covers more than just imitation, and if the other aspects of mimesis were necessary for launching language then by all means let us ask what selective pressures encouraged them. That would hardly make it wrong to ask about imitation as well, however (see also Byrne & Russon 1998).
3. Lucas calls on the authority of Chomsky (1972, 1988) to question my assumption that language is adaptive. Had anyone else but Chomsky made his off-hand remarks about language evolution they would long ago have been quietly forgotten. Pinker and Bloom are not the only ones to make sober, detailed, arguments that refute Chomsky's strange view. (See, for example, Newmeyer 1998). (In truth, Chomsky's views on evolution always give me considerable comfort. It is good to know that even geniuses can say far-fetched things.) Of course I do not know for dead certain that language was an adaptation, but we know of no other biological phenomenon that is as complex as language that we can explain in any other way except as an adaptation. Taking adaptation as a premise is often a productive strategy in studying evolution, and I think it far more likely to lead us to interesting questions and interesting answers, than saying, in effect, "it just happened", which is, basically, the Gould-Chomsky position (Gould 1977).
4. It was not my intention to imply that ontogeny recapitulates phylogeny, but I do not find it wrong to look for hints about how our ancestors might have learned words by looking at the way our own children do so. Lucas fears that I may use the example of children to conclude, incorrectly, that the earliest word users used both the speaker's gestural and intonational cues and the nonverbal context within which the words are used as a support for understanding. Not only children, but human adults and other primates always interpret signals within a context. I plead guilty to believing that early human speakers did so as well. Indeed, I find it impossible to imagine what a totally decontextualized word, if used by any ancient or modern human being, would be like.
5. The impression that I draw from Lucas's commentary is that she disapproves of speculation about the evolution of language because the evidence is too thin to be convincing. She is conceivably right. Perhaps we will never know more than we do now. But we will not know unless we try.
6. Prudkov (1999), by contrast, has no fear of speculation. Most of his commentary is an exposition of his own theory, and I will limit my response to the few places where he directly addresses my target article. First, he suggests that chimpanzee nursing pokes could not be shared by an entire group because they are used for too short a time. There are more fundamental reasons than lack of time why they could not be used by an entire group. Chimpanzees do not learn to make communicative signals by observing the signals of others. Even if they did, a nursing poke would be useless for any other chimpanzee than the single mother-baby pair that conventionalizes it.
7. Prudkov suggests that the four cognitive prerequisites that I mention in my article (a rich understanding of the external world, inference of referential intentions, icons and indices, and imitation) could have developed simultaneously with language rather than ahead of it. Most of these prerequisites are found, at least incipiently, among the apes. These cognitive abilities certainly may have been strengthened as language developed, but if they are foreshadowed in apes I see no reason to doubt that they were also foreshadowed in our prelinguistic ancestors (see Wilkins & Wakefield 1995).
8. One continues to hope that future commentaries will propose answers to the questions that I raised in my target article.
Byrne, R.W. & Russon, A.E. (1998). Learning by imitation: A hierarchical approach. Behavioral and Brain Sciences, 21(5) 667-690. ftp://ftp.princeton.edu/pub/harnad/BBS/.WWW/bbs.byrne.html
Burling, R. (1999). The cognitive prerequisites for language: Target article on language prerequisites. PSYCOLOQUY 10(032). ftp://ftp.princeton.edu/pub/harnad/Psycoloquy/1999.volume.10/ psyc.99.10.032.language-prerequisites.1.burling http://www.cogsci.soton.ac.uk/psyc-bin/newspy?10.032
Chomsky, N. (1972). Language and Mind (extended edition). New York: Harcourt, Brace, & Jovanovich.
Chomsky, N. (1988). Language and Problems of Knowledge: The Managua Lectures. Cambridge, MA: MIT Press.
Donald, M. (1991). Origins of the Modern Mind: Three Stages in the Evolution of Culture and Cognition. Cambridge, MA: Harvard University Press. ftp://ftp.princeton.edu/pub/harnad/BBS/.WWW/bbs.donald.html
Gould, S.J. (1977). Ontogeny and Phylogeny. Cambridge, MA: Harvard University Press.
Lucas, Margery. (1999). Selection pressures for language prerequisites: Constraints and limitations. PSYCOLOQUY 10(050). ftp://ftp.princeton.edu/pub/harnad/Psycoloquy/1999.volume.10/ psyc.99.10.050.language-prerequisites.2.lucas http://www.cogsci.soton.ac.uk/psyc-bin/newspy?10.050
Newmeyer, Frederick J. (1998), On the supposed 'counterfunctionality' of Universal Grammar: some evolutionary implications. In J. Hurford, M. J. Studdert-Kennedy, and C. Knight, editors, Approaches to the Evolution of Language. 305-319.
Pinker, S. & Bloom, P. (1990) Natural language and natural selection. Behavioral & Brain Sciences, 13:707-784. ftp://ftp.princeton.edu/pub/harnad/BBS/.WWW/bbs.pinker.html
Prudkov, Pavel N. (1999). The role of motivation in origin of language. PSYCOLOQUY 10(069). ftp://ftp.princeton.edu/pub/harnad/Psycoloquy/1999.volume.10/ psyc.99.10.069.language-prerequisites.3.prudkov http://www.cogsci.soton.ac.uk/psyc-bin/newspy?10.069
Wilkins, W.K. & Wakefield, J. (1995). Brain evolution and neurolinguistic preconditions. Behavioral and Brain Sciences 18 (1): 161-226. ftp://ftp.princeton.edu/pub/harnad/BBS/.WWW/bbs.wilkins.html