Environmental factors drive language density more in food-producing than in hunter–gatherer populations

Abstract

Linguistic diversity is a key aspect of human population diversity and shapes much of our social and cognitive lives. To a considerable extent, the distribution of this diversity is driven by environmental factors such as climate or coast access. An unresolved question is whether the relevant factors have remained constant over time. Here, we address this question at a global scale. We approximate the difference between pre- versus post-Neolithic populations by the difference between modern hunter-gatherer versus food-producing populations. Using a novel geostatistical approach of estimating language and language family densities, we show that environmental-chiefly climate factors-have driven the language density of food-producing populations considerably more strongly than the language density of hunter-gatherer populations. Current evidence suggests that the population dynamics of modern hunter-gatherers is very similar to that of what can be reconstructed from the Palaeolithic record. Based on this, we cautiously infer that the impact of environmental factors on language densities underwent a substantial change with the transition to agriculture. After this transition, the environmental impact on language diversity in food-producing populations has remained relatively stable since it can also be detected-albeit in slightly weaker form-in models that capture the reduced linguistic diversity during large-scale language spreads in the Mid-Holocene.

The ecological drivers of variation in global language diversity

“…However, we find that seasonality in temperature and precipitation have additional associations with language diversity that is not attributable to mean growing season. This is consistent with a recent study that supports associations between language diversity and average amount of precipitation in the wettest quarter and temperature in the warmest quarter 36 . Although growing season is defined by the number of days above a specific minimum temperature and moisture availability, seasonality will reflect both minimum and maximum of temperatures and moisture.…”

The ecological drivers of variation in global language diversity

“…However, we find that seasonality in temperature and precipitation have additional association with language diversity that is not due to mean growing season. This is consistent with a recent study that supports associations between language diversity and precipitation in the wettest quarter and temperature in the warmest quarter 34 . While growing season is defined by the number of days above a defined minimum temperature and moisture availability, seasonality will reflect both minimum and maximum of temperatures and moisture.…”

Diversity begets diversity in mammal species and human cultures

“…For example, while more productive environments house more species, tropical ecosystems house more diversity at all scales than would be expected by environmental production alone 15,26 . Similarly, studies of human cultures show that while diversity tends to be higher in more productive environments 1,3,4,6,23,24,40 there are many other environmental, climatic, geological, and cultural processes that impact diversity at various scales [40][41][42][43][44][45] . For example, while global variation in hunter-gatherer population density, space use, and mobility is well-predicted by environmental productivity 44,46,47 , the spatial distribution of ethnolinguistic groups in general across the socioeconomic spectrum is better predicted by their level of sociopolitical complexity 45,48 .…”