@article{Kaplan2009,
author = {Kaplan, H.S. and Hooper, P.L. and Gurven, M. },
title= {The evolutionary and ecological roots of human social organization},
year = {2009},
doi = {10.1098/rstb.2009.0115},
journal = {Philosophical Transactions of the Royal Society B: Biological Sciences },
volume = {364},
number = {1533},
pages = {3289--3299},
}