War, space, and the evolution of Old World complex societies. By Peter Turchin, Thomas E. Currie, Edward A. L. Turner, and Sergey Gavrilets. PNAS, published online before print, September 23, 2013. Also here.
human societies evolve from small groups, integrated by face-to-face
cooperation, to huge anonymous societies of today, typically organized as
states? Why is there so much variation in the ability of different human
populations to construct viable states? Existing theories are usually
formulated as verbal models and, as a result, do not yield sharply defined,
quantitative predictions that could be unambiguously tested with data. Here we
develop a cultural evolutionary model that predicts where and when the
largest-scale complex societies arose in human history. The central premise of
the model, which we test, is that costly institutions that enabled large human
groups to function without splitting up evolved as a result of intense
competition between societies—primarily warfare. Warfare intensity, in turn,
depended on the spread of historically attested military technologies (e.g.,
chariots and cavalry) and on geographic factors (e.g., rugged landscape). The
model was simulated within a realistic landscape of the Afroeurasian landmass
and its predictions were tested against a large dataset documenting the
spatiotemporal distribution of historical large-scale societies in Afroeurasia
between 1,500 BCE and 1,500 CE. The model-predicted pattern of spread of
large-scale societies was very similar to the observed one. Overall, the model
explained 65% of variance in the data. An alternative model, omitting the
effect of diffusing military technologies, explained only 16% of variance. Our
results support theories that emphasize the role of institutions in
state-building and suggest a possible explanation why a long history of
statehood is positively correlated with political stability, institutional
quality, and income per capita.
War Drove the Rise of Civilizations. By Akshat Rathi. Real Clear Science, September 25, 2013. Also at The Conversation.
Human cycles: History as science. By Laura Spinney. Nature, Vol. 488, Issue 7409, August 2, 2012. Also here.
Warfare the Key to Evolution of Complex Society? Popular Archaeology, September 23, 2013.
Horses a key part of rise in empires, research shows. Horsetalk, September 28, 2013.
War and space: Simulating the evolution of Old World complex societies. By Tom Currie. Video. NIMBioS, April 18, 2013. YouTube.