Origins of human language in Southern Africa?

[Östen Dahl]

Atkinson says:
"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"
and
"If phoneme distinctions are more likely to be lost in small founder populations, then a succession
of founder events during range expansion should progressively reduce phonemic diversity with increasing
distance from the point of origin, paralleling the serial founder effect observed in population genetics". 

-- It is possible that there is such a founder effect in phonology, but if it exists, it is not parallel to the genetic founder effect. In a genetic bottleneck, interindividual variation in the gene pool is reduced due to the small size of the population. But the number of phonemes has nothing to do with interindividual variation. Perhaps we would have a parallel if the average number of allophones per phoneme decreased in a founder event. If the number of phonemes is reduced, that would rather correspond to the loss of genes.

- östen

-----Ursprungligt meddelande-----
Från: funknet-bounces at mailman.rice.edu [mailto:funknet-bounces at mailman.rice.edu] För A. Katz
Skickat: den 16 april 2011 21:54
Till: Bill Croft
Kopia: Funknet
Ämne: Re: [FUNKNET] Origins of human language in Southern Africa?

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
>
>