Fairer sex drove evolution

Importance of females in primate evolution

source: Robert Adler
New Scientist no 2422, November 22 2003 p16

Three studies confirm the importance of females in primate evolution. Joan Silk and team, from California University, Los Angeles, have found that the survival of baboon offspring is linked to the strength of the social bonds of the mothers. Their work is based of 16 years' research in Kenya. Females remain with their groups, setting up relationships that last for life, and they set up coalitions. Males, in contrast, tend to move away from their natal groups. Almost 25% more of the very sociable females' offspring survived to be a year old, compared to offspring from mothers who were less sociable, and this was not affected by the status of the mother. Meanwhile, University of Pennsylvania, Philadelphia's Thore Bergman, has studied the impact of simulated role reversals, using tapes which trick baboons into thinking that higher ranking baboons have switched status with lower ranking baboons. He has found that females are more affected when the apparent role reversal involves more than one family, rather than a reversal within the family. This appears to show cognitive skills, since reversals involving more than one family affect the whole group. In a third study, University of Virginia, Charlottesville's Patrik Lindenfors, has studied primate evolution. He has found that increases in male size follow the development of species with large groups of females. Females appear to be important in the development of both large groups, and the intelligence needed to be part of those groups.