Generally, when a woman chooses a mate outside her own IQ or educational group, she tends to marry up. This tendency cuts across culture, ethnic group and race. Even in developing countries, such as Nigeria, romantic partners tend to have the same level of education, but when there is a difference in schooling, females usually marry up. This is the long-standing pattern in the United States, but it is an inescapable consequence of the fact that females were excluded from higher education. More recently, the number of females earning advanced degrees has climbed steadily, surpassing the number of males in 2003, while the trend line has been dropping for men. Now that the gender gap in education favors females, women in the modern world are more frequently marrying down when it comes to scholastic smarts and income.

At times and in places where choices are limited, women, with biological clocks ticking, will be satisfied with the Neandertal rather than remain unsatisfied—the CSN law of compromise under scarcity, “Love the One You Are With.” One can imagine that at times of male scarcity in the struggle for survival through ice ages, disease, and men killing each other in battle, the attractiveness of eligible males would rise, even if they were Neandertals.