This relates to an article in Science by Quentin D. Atkinson, an evolutionary psychologist/anthropologist from the universities of Auckland and Oxford. His claim can be summed up as: The more phonemes a language has, the closer it is to the putative origin of human language, in Africa. The fewer phonemes it has, the further away from Africa along the track of presumed human settlement: Africa – Eurasia – America and Oceania.
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.
Before we go any further, let me refer you to the excellent discussion of this topic that Mark Liberman has just contributed to Language Log, a discussion which I would urge you to read. He queries the bizarre metric used by Atkinson, which means inter alia that ‘losing a single tone would generally reduce "Total Phoneme Diversity" by as much as losing about 10 consonants would’. Atkinson also ignores syllable structure differences and what they imply.
Nevertheless, Atkinson’s claim is interesting and thought-provoking.
Atkinson’s claim relates to large-scale families of languages rather than to individual languages or dialects. While it may or may not be justified as a generalization on this macro scale, it clearly does not work in specific cases on a micro scale, as can be seen from the considerable scatter around the trend line on his diagram.
Russian has more phonemes than Polish. Portuguese and Catalan have more than Spanish. Marathi has more than Hindi. In none of these cases does it correlate with being closer to Africa.
But yes, Ju|’hoan in Namibia, with four tones, 30+ vowels and 89 consonants (including 48 clicks) easily beats Hawaiian with its parsimonious eight consonants and five vowels.