One plausible sequence of events was that early humans, having developed sharp tools and the physical capacity to kill at a distance using projectile weapons, so lowered the cost of punishing lying , cheating, and other anti-social acts that it became possible to ensure that communication could be highly veritable. At this point, the value of a complex language would likely have increased by several orders of magnitude over the usual situation for social species, where there is virtually no means of punishing false and misleading messages. From this point, the coevolution of culture and genes led to the full development of the human linguistic capacity, allowing for a degree of human social organization permitting long-term spatial diversification and population growth.
Why We Talk: The Evolutionary Origins of Language
Jean-Louis Dessalles
Oxford University Press 2009 PDF 397 pages 3,73 mb
http://www.filesonic.com/file/25039915/0199563462.pdf
