Thus paternal grandmothers were most beneficial to the survival of their granddaughters and least beneficial to the survival of their grandsons, while maternal grandmothers showed an intermediate effectiveness.
Experts are thrilled by the findings. "Wow, very interesting," says Hawkes. "The consistent results across seven populations ... seem to clarify previously inconsistent results." Lorena Madrigal, an anthropologist at the University of South Florida in Tampa, calls the study "an important contribution to a topic of great interest to evolutionary biologists."
