Old Wolf writes "A New Zealand evolutionary psychologist, Quentin Atkinson, has created a scientific sensation by claiming to have discovered the mother of all mother tongues. 'Dr Atkinson took 504 languages and plotted the number of phonemes in each (corrected for recent population growth, when significant) against the distance between the place where the language is spoken and 2,500 putative points of origin, scattered across the world (abstract). The relationship that emerges suggests the actual point of origin is in central or southern Africa, and that all modern languages do, indeed, have a common root."
Reader NotSanguine points out another study
which challenges the idea that the brain is more important to the structure of language
than cultural evolution.