On the Evolving Biology of Language.

Abstract

Some language scientists defend an anti-Darwin account and believe in the saltational evolution of modern language. They emphasize that the language faculty emerged by a sudden mutation in the last 50–100 ky (e.g., Klein, 2000; Chomsky, 2012, 2015; Berwick et al., 2013). In contrast, others claim that modern language is the product of a gradual co-evolution of neurobiological and cultural-linguistic conditions, which took place since genus Pan was separated for good from the hominin lineage about 4–6 mya (e.g., Pinker and Bloom, 1990; Pinker, 1994; Deacon, 1997; Dor and Jablonka, 2001; Falk, 2004; Enfield and Levinson, 2006; Levinson and Jaisson, 2006; Christiansen and Chater, 2008; Atkinson, 2011; Dunn et al., 2011; Dediu and Levinson, 2014). New genetic evidence and their interpretation in context of fossil and artifact discoveries shed however light on this controversy. The data indicate that pre-modern language might have been already spoken by Homo erectus. Moreover, we conclude that the sister species of modern humans, Neanderthals and Denisovans, may have used language much like modern humans do (e.g., Dediu and Levinson, 2013). To begin with, it is important to distinguish between the biology of modern language, that is, the language-ready brain and the availability of a linguistic code. For instance, a particular Homo species might have had a (pre-)modern language-ready brain but the language that was used at that time may have been different from modern language. Basic design features including combinatory, compositional as well as complex hierarchical structures are cultural products, which may have co-evolved along with genetic changes over a long period of time. Modern language as we experience it today may require not only cortical wiring for language-specific operations but also a certain cortical mass to express thoughts and complex concepts. It would go beyond the present scope to discuss details but we assume here that the complex properties of modern language at all linguistic levels are from an evolutionary viewpoint mutually related to the principles of complex concept formations. An increase of the cranial capacity resulted in forming multi-modal memory systems. It seems thus plausible to assume that spoken language processing skills evolved alongside in order to communicate these sensory and episodic experiences. The dramatic brain growth started with Homo habilis, which is sometimes considered to have an anagenetic relationship to the species H. erectus (Spoor et al., 2007). Again, sometimes Homo heidelbergensis has been classified as part of the H. erectus group by taking account of a broad range of individual differences (Lordkipanidze et al., 2013). The species H. habilis was around for 1 my, H. erectus for 1.6 my and H. heidelbergensis for 400 ky. As we will see below, the H. erectus epoch might have provided the opportunity for gradual biological adaptions resulting in refined language use. Recent genetic studies revealed factors, which may have significantly contributed to brain growth in human ancestors. Interestingly, these genetic factors seem to correspond to discrete cognitive stages in the human lineage.