@article{Hawkes1998,
author = {Hawkes, K. and O’Connell, J.F. and Blurton Jones, N.G.  and Alvarez, H. and Charnov, E.L.},
title= {Grandmothering, menopause, and the evolution of human life histories},
year = {1998},
doi = {10.1073/pnas.95.3.1336},
journal = {Proceedings of the National Academy of Sciences},
volume = {95},
number = {3},
pages = {1336--1339},
}