I'm missing Stephen Jay Gould, who would have repudiated, but with his characteristic good humor, Summers for his remarks. Gould, you'll recall, was a critic of "sociobiology," a field pioneered by his Harvard colleague E.O. Wilson. Gould and others, according to Wikipedia, "feared that [sociobiology] would be used, as similar ideas had been in the past, to justify the status quo, entrench ruling elites, and legitimize authoritarian political programmes."
Here is Summers' account (from the Harvard Crimson) of the three possible explanations for the lack of women in the sciences:
In his remarks last month, Summers suggested three “broad hypotheses” to account for the dearth of women who study and take jobs in science and engineering.
“One is what I would call the...high-powered job hypothesis,” Summers said, explaining that familial obligations often prevent women from taking jobs that require too large a time commitment—as much as 80 hours a week in the case of scientists, Summers said.
A Crimson reporter yesterday verified the transcript provided by Summers’ office against an audiotape of the remarks. Only inconsequential false starts and repeated words were omitted.
The president’s second—and ultimately most controversial—hypothesis focused on what he referred to as “different availability of aptitude at the high end.”
Elaborating on that explanation, Summers said, “It does appear that on many, many different human attributes—height, weight, propensity for criminality, overall IQ, mathematical ability, scientific ability—there is relatively clear evidence that whatever the difference in means, which can be debated, there is a difference in the standard deviation, and variability of a male and a female population.”
He did not use the phrase “innate differences,” which emerged as key buzzwords in the ensuing controversy over his remarks. Summers used that phrase in later media interviews describing the speech.
Summers third hypothesis focused on “different socialization and patterns of discrimination in a search,” a theory to which he bestowed relatively little importance.