Several people have emailed/tweeted at me about the new paper in Science, Phonemic Diversity Supports a Serial Founder Effect Model of Language Expansion from Africa:
Human genetic and phenotypic diversity declines with distance from Africa, as predicted by a serial founder effect in which successive population bottlenecks during range expansion progressively reduce diversity, underpinning support for an African origin of modern humans. Recent work suggests that a similar founder effect may operate on human culture and language. Here I show that the number of phonemes used in a global sample of 504 languages is also clinal and fits a serial founder–effect model of expansion from an inferred origin in Africa. This result, which is not explained by more recent demographic history, local language diversity, or statistical non-independence within language families, points to parallel mechanisms shaping genetic and linguistic diversity and supports an African origin of modern human languages.
Though there are major differences between biological evolution, constrained by relatively regular forms of inheritance, and cultural evolution, which is much more potentially protean, I think that there is great potential for unity of model and process. That is why I read A Replicated Typo (and presumably why several of the contributors to that weblog read the content here). But I generally have zero ability to evaluate the linguistic plausibility of these sorts of hypotheses about the origin and development of languages.