Responding to increasing pressure from Harvard faculty that has begun to threaten his career, Harvard President Lawrence Summers authorized on Thursday the release of the transcript of controversial statements regarding female scientists that he made at a closed-door academic conference Jan. 14.

The transcript, which Summers had previously refused to release, details the embattled president’s argument that there exist intrinsic differences between the sexes, combined with aspects of family structure and the job market, that could explain why fewer women than men have high-ranking jobs in the sciences. In his nearly 7,000-word speech, Summers said he was speaking unofficially and not on the “many things we’re doing at Harvard to promote the crucial objective of diversity.”

Speaking at the National Bureau of Economic Research conference in Cambridge, Mass., Summers said males and females may have different levels of aptitude in the sciences and engineering.

“In the special case of science and engineering, there are issues of intrinsic aptitude, and particularly of the variability of aptitude, and that those considerations are reinforced by what are in fact lesser factors involving socialization and continuing discrimination,” Summers said.

In an attempt to calm the storm, Summers sent a letter to the faculty in tandem with the release of the transcript Thursday in which he apologized for his comments at the conference.

“If I could turn back the clock, I would have spoken differently on matters so complex,” Summers wrote in the letter. “Though my NBER remarks were explicitly speculative, and noted that ‘I may be all wrong,’ I should have left such speculation to those more expert in the relevant fields. I especially regret the backlash directed against individuals who have taken issue with aspects of what I said.”

An economist, Summers served as the deputy treasury secretary in the Clinton administration prior to assuming the presidency of Harvard in 2001. In his address, Summers recounted a story about his daughters which he believed could explain his position on women in the sciences.

“So, I think, while I would prefer to believe otherwise, I guess my experience with my two-and-a-half year old twin daughters who were not given dolls and who were given trucks, and found themselves saying to each other, ‘Look, daddy truck is carrying the baby truck,’ tells me something,” Summers said. “And I think it’s just something that you probably have to recognize.”

In the speech, Summers made several generalized statements about the racial and gender composition of various fields. He noted the underrepresentation of Catholics in investment banking, white men in the National Basketball Association and Jews in agriculture and farming. He also suggested that there is a difference between men and women in regard to many standard measures.

“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,” Summers said.

Summers ended his speech with a disclaimer: his remarks were only his “best guesses.” But today, Summers is paying for those guesses as he is facing increasing criticism of his tenure from several Harvard professors. The faculty will gather in an emergency meeting on Tuesday, which may include a vote of confidence in Summers.