Proceedings of the National Academy of Sciences of the United States of America, vol 115, iss 2 Turchin, P, Currie, T E, Whitehouse, H, François, P, Feeney, K, Mullins, D, Hoyer, D, Collins, C, Grohmann, S, Savage, P, Mendel-Gleason, G, Turner, E, Dupeyron, A, Cioni, E, Reddish, J, Levine, J, Jordan, G, Brandl, E, Williams, A, Cesaretti, R, Krueger, M, Ceccarelli, A, Figliulo-Rosswurm, J, Tuan, P J, Peregrine, P, Marciniak, A, Preiser-Kapeller, J, Kradin, N, Korotayev, A, Palmisano, A, Baker, D, Bidmead, J, Bol, P, Christian, D, Cook, C, Covey, A, Feinman, G, Júlíusson, Á D, Kristinsson, A, Miksic, J, Mostern, R, Petrie, C, Rudiak-Gould, P, ter Haar, B, Wallace, V, Mair, V, Xie, L, Baines, J, Bridges, E, Manning, J, Lockhart, B, Bogaard, A & Spencer, C 2017, ' Quantitative historical analysis uncovers a single dimension of complexity that structures global variation in human social organization ', Proceedings of the National Academy of Sciences (PNAS), vol. 115, no. 2, pp. E144-E151 . https://doi.org/10.1073/pnas.1708800115 Proceedings of the National Academy of Sciences of the United States of America