Head to edge.org  to watch this  video of Thomas W Malone speaking about Collective Intelligence.  Among his many interesting findings, he discloses a significant gem about gender and intelligence of groups.  Malone teaches at MIT Sloan School of Management.

at 9:05:

“we found that the collective intelligence of the group was significantly correlated with the percentage of women in the group… it looks like it’s a more or less linear trend where more women are better all the way up to all women.  Now, Also important to realize that the gender effect is largely statistically mediated by the social perceptiveness effect.”