Cultural evolution and gender roles: A re-affirmation of J.K. Brown's note

In 1970, Brown offered "A note on the division of labor." Her observation w as that - across cultures - if a task interfered with child-rearing, then t hat task would be given to men. If a task did not interfere with child-rear ing, then that task could be included in the set of chores assigned to wome n. A reasonable extension of her note would be that if a group's women, as a class, were performing tasks incompatible with child-rearing, then the fe rtility rates of that group's women would be decreased. A cross-cultural su rvey of current demographic indices re-affirms Brown's note. Data are prese nted which indicate that, as more of a group's women perform tasks which ar e incompatible with child-rearing, the lower the fertility rate of that gro up's women. As a corollary, there are systematic cultural evolutionary pres sures for groups with higher fertility rates to replace or displace groups with lower fertility rates.