I had expressed scepticism of that paper on different grounds; also somewhat related, I recently chanced upon a piece in Scientific American suggests that click sounds, for which languages of South Africa are famous are also found in English.
Getting back to the current article, quoting from a preprint I had obtained a while back:
Notwithstanding this criticism, we replicated Atkinson’s method using the UPSID data, but instead of a single origin in West Africa, we found two separate ‘origins’, one in East Africa and one in the Caucasus (Fig. S10). The BIC+4 range of possible origins covers a large area including also the Middle East and South Africa. Although this finding does not necessarily contradict an expansion form Africa, it does not provide clear support in its favor, either. Further, adding a quadratic distance factor to the model substantially improves the fit and suggests an alternative origin located in New Guinea with a small phoneme inventory (Fig. S10). Even more problematic, when we apply the original method to other inventory-like linguistic characteristics from WALS (Fig. 1) we find origins of global clines all over the world, not just in Africa, and not always corresponding to the highest structural ‘complexity’ (Fig. S11). Therefore, the observation of an Africa-based phoneme inventory cline does not generalize to other linguistic characteristics of a similar kind.
It would be great if linguistic methods could pinpoint the origin of language, but I am not so sure that it can be done. We don't even know which groups of hominins could speak. Interestingly a Kebaran Neandertal apparently had hyoid bones that suggested a modern-like capacity for speech. On the other hand, Kebara was apparently atypical of Neandertals in other aspects of morphology, deviating in a modern human direction, and postdating the major human expansion placed c. 70,000 years ago.
So, it may very well be that language was indeed unique to Homo sapiens, although, as the current paper aptly shows, tracing its origin in space may prove to be quite a challenge.
Science 10 February 2012: Vol. 335 no. 6069 p. 657 DOI: 10.1126/science.1208841
Comment on “Phonemic Diversity Supports a Serial Founder Effect Model of Language Expansion from Africa”
Michael Cysouw et al.
We show that Atkinson’s (Reports, 15 April 2011, p. 346) intriguing proposal—that global linguistic diversity supports a single language origin in Africa—is an artifact of using suboptimal data, biased methodology, and unjustified assumptions. We criticize his approach using more suitable data, and we additionally provide new results suggesting a more complex scenario for the emergence of global linguistic diversity.