Languages Change in Punctuational Bursts

This nice little paper from Science (Vol 319, 2008 ) presents evidence that languages undergo an initial period of strong seperation, where the rate of change is high, and then slow down into a steadier pace of change. They hypothesise that this is due to a cultural need to establish a seperate identity, or as a product of the way we use language to enhance group cohesion in times of cultural upheaval. A nice hypothesis that, if true, would demonstrate the power of cutltural transmission upon language structure. It fits roughly into the same line of argument as Kirby, Hurford, Smith (K) et al.