The demise of many sex differences with increasing gender equality is a prediction of social role theory

As women’s social, occupational, and political engagement expanded in Western nations, social scientists anticipated a great psychological and behavioural convergence of men and women.

But instead of convergence of the sexes, we have something closer to a great divergence, says Andrew Keen .

Keen: Many psychological, behavioural sex differences are larger in more gender-equal countries.

Keen says biological changes are likely driven by biological changes, not down to evolutionary selection.

Height provides a clearcut, incontrovertible example of how favourable environments affect sex differences in biology.

As living conditions improve, men gain twice as much in height and weight as women.

Men’s relative height is compromised the most if they experience nutritional and caloric deficits in the first few years of life or during the pubertal growth spurt.

Pretermgirls (born at 3233 weeks , extremely preterm girls exposed to stress or exposure to stress) suffer relative deficits to full-term girls, whereas boys exposed to the same stressors hardly suffer at all in many physical competencies.

It makes sense in terms of wealthy egalitarian societies offering more options in life and looser social mores that enable the fuller expression of underlying sex differences in personality, proclivities, and lifestyle preferences.

Post hoc explanations, such as stereotypes and the stubborn persistence of the patriarchy, will still be offered in an attempt to rescue the blank-slate theory.