Origins of human language in Southern Africa?

[A. Katz]

Much of what you explain here makes a great deal of sense, but is the 
assumption really that the original phonetic inventory was small, and that 
it increased over time. I would think it would be the other way around.

Wouldn't a larger number of interlocutors level phonetic distinctions due 
to noise in the signal?



    --Aya



On Sat, 16 Apr 2011, Bill Croft wrote:

> I have just read Atkinson's article, including the supplementary materials - 
> the supplementary materials for a Science or Nature article are essential 
> reading, because the actual article is too short to be more than just a long 
> abstract for the real paper.
>
> A number of linguists, here on Funknet just now but also in the comments 
> section of the NY Times article by Nicholas Wade, have pointed out languages 
> that are at a substantial distance from Africa but have large phoneme 
> inventories as evidence against the hypothesis. It is worth putting this in 
> context of what the paper actually says:
>
> "We expect the number of phonemes present in a language today to reflect past
> phoneme inventory size, combined with complex group dynamic processes driving
> relative rates of merging, splitting and borrowing of phonemes. Many
> factors are likely to influence the rates at which these processes occur, and
> their relative rates will determine the trajectory of phonemic diversity in a 
> language
> through time." (supplementary materials, p. 8)
>
> "It is worth noting that fitting a serial founder effect model to phoneme 
> inventory data
> describes an inherently stochastic (probabilistic) process and does not 
> entail that
> phonemic diversity is entirely determined by population size via a serial 
> founder
> effect. Distance from the best-fit origin in Africa and population size are 
> shown to be
> significant predictors of phonemic diversity, explaining approximately 30% of 
> global
> variation, but other sociolinguistic processes and more recent population
> movements clearly also play a role. Neither of these factors are expected to
> systematically bias results to produce the observed global cline in phonemic 
> diversity."
> (supplementary materials, p. 11)
>
> "In a general linear model,
> language family as a factor explains 50% of the variance in phonemic 
> diversity
> (adjusted r-squared=0.502, df=49, p<0.001) and 48% of the variance in 
> phonemic
> diversity across the largest 10 families (adjusted r-squared=0.476, df=9, 
> p<0.001).
> This level of conservation within major language families indicates that 
> robust
> statistical patterns in global phonemic diversity can persist for many 
> millennia and
> could plausibly reflect a time scale on the order of the African exodus." 
> (supplementary materials, p. 7)
>
> In other words, Atkinson argues that distance from Africa is only one of many 
> factors accounting for phoneme inventory size, and explains only part of the 
> variance in phoneme inventory size. The conclusion of the main article states 
> that distance from Africa explains 19% of the variation in phonemic diversity 
> (p. 348). Population size (also documented by Hay & Bauer, Language 2007) 
> explains another part, and language family explains yet another, quite large, 
> part of variation in phoneme inventory size. These statistical models are 
> examples of the competing motivation models that many functionalists argue 
> for. The point of the article is that there is still a signal of an African 
> phylogenetic origin of modern human language in the geographical distribution 
> of this typological trait.
>
> Atkinson offers an explanation based on the small size of founder populations 
> leading to the reduction of phoneme inventories, in turned based on the 
> correlation between population size and phoneme inventory. So the explanation 
> is in turn based on whatever explanation is offered for the latter 
> correlation. That is the most interesting and most problematic part of the 
> whole story, in my opinion. Atkinson presents an implausible explanation on 
> p. 3 of the supplementary materials, but the more extended discussion on pp. 
> 8-10 is better. Hay and Bauer do not endorse any specific explanation, but 
> suggest that in small social networks context allows more ambiguity to exist 
> (hence fewer phonemes are necessary), and exposure to a larger number of 
> interlocutors may enhance the creation and maintenance of a larger number of 
> phonemic distinctions, citing respectively social network theories and 
> frequency- and exemplar-based theories of phonology.
>
> Atkinson's conclusion seems reasonable to me. The statistical signal seems 
> robust, even if we have difficulty in explaining it. I encourage you to read 
> the article and supplementary materials and judge for yourself.
>
> Bill
>
>