Rapid, global demographic expansions after the origins of agriculture
- May 23, 2013
- 2 min read
The invention of agriculture is widely assumed to have driven recent human population growth. However, direct genetic evidence for population growth after independent agricultural origins has been elusive. We estimated population sizes through time from a set of globally distributed whole mitochondrial genomes, after separating lineages associated with agricultural populations from those associated with hunter-gatherers. The coalescent-based analysis revealed strong evidence for distinct demographic expansions in Europe, southeastern Asia, and sub-Saharan Africa within the past 10,000 y. Estimates of the timing of population growth based on genetic data correspond neatly to dates for the initial origins of agriculture derived from archaeological evidence. Comparisons of rates of population growth through time reveal that the invention of agriculture facilitated a fivefold increase in population growth relative to more ancient expansions of hunter-gatherers.
The authors make a good argument that if hunter-gatherers had adopted agriculture early on, then there would be a signal of population growth in hunter-gatherer derived haplogroups at the same time as the onset of the farming economy.
Map showing the rate of agricultural population growth for Europe interpolated via Kriging from archaeological data on the Neolithic incursion.
(A) The dates of the initial Neolithic (agricultural) remains based on 665 calibrated radiocarbon archaeological sites from Pinhasi et al. (23). Units are in years.
(B) The timing of each archaeological site was then paired with the appropriate population growth rate during the same time interval calculated from our European Neolithic Skyline analysis seen in Fig. 1 assuming a wavefront expansion. Darker colors indicate more rapid population growth; lighter colors indicate slower population growth.
Comments