The size distribution of conspecific populations: the peoples of New Guinea

Abstract

The size distribution of the language populations in New Guinea, which represent over 15% of the world's languages, is analysed using models analogous to the resource division models of species abundance distribution in ecological communities. A model distribution of resource segments re£ecting population size is created by repeated selection of an existing resource segment and its division into two. We found that any dependency of the selection probability on the size of the segment generated negatively skewed abundance distributions after log transformation. Asymmetric segment division further exacerbated the negative skewness. Size-independent selection produced lognormal abundance distributions, irrespective of the segment division method. Size-dependent selection and asymmetric division were deemed reasonable assumptions since large language populations are more likely to generate isolates, which develop into new populations, than small ones, and these isolates are likely to be small relative to the progenitor population. A negatively skewed distribution of the log-transformed population sizes was therefore expected. However, the observed distributions were lognormal, scale invariant for areas containing between 100 and over 1000 language populations. The dynamics of language di¡erentiation, as re£ected by the models, may therefore be unimportant relative to the e¡ect of variable growth rates among populations. All lognormal distributions from resource division models had a higher variance than the observed one, where half of the 1053 populations had between 350 and 3000 individuals. The possible mechanisms maintaining such a low variance around a modal population size of 1000 are discussed.

Model of World: Her Cities, Languages and Countries

“…The time evolution of the cities (or the languages and their families) is considered in terms of two random processes, the multiplicative random noise [1] and the random fragmentation [2], which are coupled; here, the cities or the languages (and their families) are taken as a whole and the individuals are ignored. The cities grow in number by splitting (with constant ratio S = 1/2) where, the fragmentation rate is H; and, the languages, the city families and the language families follow them accordingly, with various fragmentation rates: If a new city forms a new language (h f ) then it means that, the language of the home city is fragmented; here, the splitting ratio (S) is the ratio of the population of this new city to the total population of the cities which speak the old language.…”

“…The area plot depicts fluctuation; yet, it roughly follows the population line. The inset (Figure 1) is for the population density in capita per km 2 , which shows that the population density is almost constant (about 18.5 capita per km 2 ) over the countries.…”

“…The whole life goes on over an area of some 510 million km 2 . Figure 1 is plotted utilizing the present empirical data [6] for the relative population of the countries (divided by the world population, thick line) in rank order; i.e., the most populous country (China) has the rank one, the next populous country (India) has the rank two, and the third populous country (USA) has the rank three, etc., where the corresponding relative area of the countries (divided by the area of the Earth) is designated by the plot in the thin line.…”

Demographic Growth and the Distribution of Language Sizes

“…This is in turn consistent with the hypothesis that, over sufficiently long time scales, the population speaking a given language evolves autonomously, driven just by demographic processes. 16 Let p…”

“…This can be readily assessed from empirical data on the number of speakers of individual languages and, in fact, has already been pointed out for a set of some 1,000 New Guinean languages. 16 Here, I analyze the size distribution of languages belonging to each one of the four largest families, according to Ethnologue's classification. 18 Population data for individual languages were obtained from Ethnologue's online databases.…”