In monkeys, a spatial-memory gender gap closes with age | Science Blog:
Given the heated debate about whether men and women have brain differences that affect cognition, psychologists are searching for definitive answers. However, research in humans is confounded by factors such as diet, medication, lifestyles, rearing and culture. As a result, psychologists are studying non-human primates in controlled setting to get a clearer, less distorted picture.
New cross-sectional studies of Rhesus monkeys spotlight a gender gap in their spatial memory, but only in young adulthood and only with untrained females.
So smoothly they slip to closely related species. Like they take our relationship with the primates for granted. Like it's more than "just a theory." It's a well documented theory that helps explain whether Larry Summers was right or wrong.