Who Helps and Why? - Kasper, Claudia; Mulder, Monique Borgerhoff; Baird, Timothy D.; Caudell, Mark A.; Green, Maia; Hadley, Craig; Kaiser, Bonnie; Hames, Raymond; Jaeggi, Adrian V.; Gurven, Michael; Koster, Jeremy; Lesorogol, Carolyn; et al. (Current Anthropology, 2015)