Implications of Land Development on Nomadic Pastoralism: Ecological Relaxation and Biosocial Diversity in Human Populations

Nomadic pastoralism is an ancient subsistence strategy, historically balanced and in continuity with sedentary societies. Sedentarization of nomads occurs normally because of ecological disasters, economic opportunities, urbanization, and government policy. In this paper, I examine the effect of changing land use patterns on nomadic pastoral populations in Asia, Africa, and the Middle East, using biogeographic methodology to further explore the contemporary relationship between humans and their environments. Nomadic population information gleaned from diverse ethnographic studies, and GIS data on anthropogenic biome distributions, were used to calculate changes in nomadic population, area of developed land, and nomadic/sedentary population density over the last century in seven countries. There was a significant decrease in the proportion of national populations practicing nomadic pastoralism (paired t-test, p=0.0038, n=7), but no significant overall change in total nomadic populations (paired t-test, p=0.41, n=7); nomadic population decreased in all countries but Sudan and Somalia. There was also no significant change in undeveloped land available for nomadic pastoralism (mean change -12.5%, S.D. ±15.8, paired t-test p=0.07, n=7), though the area of land available for nomadic pastoralism decreased in most countries. There was a negative linear correlation between land development and nomadic population when Somalia and Sudan were omitted (r2=0.84). Nomadic population density decreased in most countries, but increased in Somalia and Sudan. Some nomadic populations may be experiencing an extinction debt effect, where habitat loss combines with increased population density (Somalia, Sudan), but in most others where the population seemed to decrease more rapidly than would be expected due to habitat loss (Saudi Arabia, Mauritania, Iraq, and Afghanistan). The variable relationship between density and habitat loss implies that social factors often overshadow the ecological: though there is a correlation between habitat loss and nomadic population decline, causation is unclear. Despite the limitations of this study, nomadic populations do seem to have a natural balance with their cultural and biological environments that is disrupted by changes in social dynamics with sedentary populations and their subsequent environmental impacts. The loss of cultural diversity inherent in this disruption may decrease the flexibility and adaptability of the overall biosocial human ecosystem