Are there features of language that arose like birds' feathers?
On some modern theories of language genesis, certain fundamental features of language arose, like birds' feathers, through exaptation. The article offers a critical appraisal of three of these theories, namely those of Lieberman, Wilkins and Wakefield, and Calvin and Bickerton. It argues that these theories fail to assign to the features of language in question the status of 'exaptation' in a non-ad hoc and non-arbitrary way: these theories are not embedded in a sufficiently restrictive general theory of exaptation. It is moreover shown that, in the absence of such a theory, it is unclear what kinds of evidence are properly relevant to the appraisal of the exaptationist claims expressed by the three theories of language genesis. © 2002 Elsevier Science Ltd. All rights reserved.