You might think a distinguished and senior professor at one of America’s most renowned universities had seen it all by now. After a few decades of teaching and writing, a top academic such as Nancy Hopkins, professor of biology at Massachusetts Institute of Technology, one might assume, would have developed a sturdy carapace of scholastic experience that would shield her from nasty side-effects of shocking solecisms by peers or students.

But this month at an academic conference in Cambridge, Massachusetts, Professor Hopkins observed something so unspeakable that, as she subsequently told reporters, it almost caused her to faint. “I just couldn't breathe,” she said. If she had stayed in the room, she went on, she would have either “blacked out or thrown up”.

What could have caused Professor Hopkins’s oesophagic crisis? Some grisly slide-show depicting the results of a hideous crime, perhaps? An outburst of obscenities from the podium? Something noxious dropped stealthily into her coffee during the mid-morning break? (You know how bitter these intra-academic rivalries can be.)

No. The answer was the spectacle of a fellow academic, a rather grand one, indulging in one of the most heinous transgressions known to humankind — daring to challenge that precious hegemonic orthodoxy of American academia, the impossibility of gender inequality.

The assailant was not some right-wing fruitcake but Larry Summers, President of Harvard University, Treasury Secretary in the Clinton Administration, the youngest and most brilliant tenured economics professor in Harvard’s history, a firm advocate of aggressive affirmative action programmes to help minorities, and a fully paid-up and credentialled member of the vast left-wing consensus that dominates US campuses.

What Summers said hardly amounted to a challenge to orthodoxy. It barely rose above the level of a tentative question. He was giving the luncheon talk to a conference organised by the National Bureau of Economic Research on the under-representation of women in science and engineering faculties at American universities.Acknowledging the basic and obvious premise of the conference that in maths and science few US faculty members are women, and even fewer at the most senior levels, he suggested three possibilities for this deficit. The first two were harmless and politically correct enough: discrimination, of which he noted many universities are certainly guilty; and the fact that success in these academic fields often requires long, antisocial hours that might discourage women with family commitments.

But a third possibility, he said, cautiously, might be that there are innate differences between the way the female and male brains work — perhaps there was something about women’s genetic makeup that made them less well equipped to excel at the highest levels of abstract mathematical reasoning.

So it was that Professor Hopkins, a long-time advocate of women’s rights, swooned. And not just Professor Hopkins. Across the country, in campuses ancient and modern, quadrangles clattered with the sound of female academics collapsing from shock at this assault on their academic freedom.

As the news spread through newspapers and the internet, wealthy alumnae cancelled their standing orders to Harvard’s bursting coffers. The student body’s female representatives rose up as one and condemned their leader. One (female) dean of a big public university, displaying an exquisite sense of proportion, taste and timing, said that Summers’s remarks had produced an “intellectual tsunami” across America.

Within days Summers had been forced into a series of ever-more grovelling apologies. Last week, in the latest version of his recantation, he sent a letter to every member of the Harvard community, begging forgiveness, promising better understanding of women’s issues, and agreeing to establish an inquiry into gender discrimination at Harvard. By this weekend he was starting to look like one of those desperate figures from China’s Cultural Revolution, surrounded by his tormentors, standing in a dunce’s hat with a sign around his neck that says: “Woman Hater”.

The Summers affair might be just another of those funny wacko stories about silly “Bah Bah Green Sheep” political correctness if it didn’t point to a corrosive weakness in American universities. Indeed, it says more about the state of the American academy than any satirist could dream up. After years in which the absurd excesses of political correctness had fallen from the front pages, it is a useful reminder that American higher education remains a largely totalitarian field, where the penalties for straying from the liberal orthodoxies of feminism, multiculturalism and relativism are severe.

It is important to remember what Summers was saying. He was most certainly not averring that women are simply genetically less capable than men of pursuing abstract scientific postulations or mathematical equations. He was merely suggesting that gender differences should not be ruled out as a possible explanation of a multi-faceted question.

There is plenty of scientific evidence at least to back up his claim that there might be some biological differences. Statistical studies of academic test scores in maths and sciences have shown consistently that males tend to be over-represented in both tails of the bell curve. Research at the (politically incorrect, presumably) University of Missouri has found that, among adolescents scoring at the top levels on standardised maths tests, males outnumber females by 13 to 1.