If men and women were psychologically distinct from one another, then their scores on psychological measures should form large clusters at either end of a spectrum with little overlap between the two groups.
This is the case for physical characteristics such as height, shoulder breadth, arm circumference, and waist-to-hip ratio. Men tend to be tall, have broad shoulders, large arm circumference, and a small waist-to-hip ratio, while the inverse is true for women. A man is extremely unlikely to be taller than a woman, yet have narrower shoulders, for instance.
Yet the same could not be said for the myriad of psychological characteristics examined by the two researchers, including fear of success, sexual attitudes, mate selection criteria, sexual behaviors, empathy, and personality. A man could be aggressive, but verbally skilled and poor at math, for example, combining stereotypical masculine and feminine traits.