Population dynamics of human language : a complex system

In the course of natural history, Evolution has come up with several great innovations, such as nucleic acids, proteins, cells, chromosomes, multi-cellular organisms, the nervous system.... The last “invention” which truly revolutionized the very rules of evolution is language. It gives us an unprecedented possibility to transmit information from generation to generation not by the “traditional” means of a genetic code, but by talking. This new mode of cross-generational information transfer has given rise to the so-called “cultural evolution”. It is responsible for a big part of being “human”. It is shaping the history and changing the rules of biology. Without exaggeration, it is one of the most fascinating traits of Homo Sapiens. The study of language and grammar dates back to classical India and Greece. In the 18th century, the “discovery” of Indo-European led to the surprising realization that very different languages can be related to each other, which initiated the field of historical linguistics. Formal language theory emerged only in the 20th century (Chomsky, 1956, 1957; Harrison, 1978): the main goals are to describe the rules that a speaker uses to generate linguistic forms (descriptive adequacy) and to explain how language competence emerges in the human brain (explanatory adequacy). These efforts were supported by advances in the mathematical and computational analysis of the process of language acquisition, a field that became known as learning theory. Currently there are increasing attempts to bring linguistic inquiry in contact with various disciplines of biology, including neurobiology (Deacon, 1997; Vargha-Khadem et al., 1998), animal behavior (Dunbar, 1996; Hauser, 1996; Fitch, 2000), evolution (Lieberman, 1984; Pinker and Bloom, 1990; Bickerton, 1990; Lieberman, 1991; Hawkins and Gell-Mann, 1992; Batali, 1994; Maynard Smith and Szathmary, 1995; Aitchinson, 1996; Hurford et al., 1998;