My friend and colleague Alice Schaerr Rossi, a co-founder of the National Organization for Women and one of the leading sociologists of her generation, died on November 3 at age 87.

For a few years in the ‘70s and ‘80s, I worked with her and Jane Lancaster, a distinguished anthropologist now at the University of New Mexico and editor of the journal Human Nature, on a committee of the Social Science Research Council, and both of them affected my thinking about gender.

But Alice was much more senior, and because she was a founder of NOW, she had impeccable feminist credentials. She was brilliant, tough-minded, compassionate, competitive, and maternal all at once, and I learned a lot from her.

I already considered myself a feminist, but being oriented to the biological bases of behavior, I could not accept the kind of feminism that insisted essentially on sameness—on the claim that there are no fundamental psychological differences between men and women, and that all purported differences were invented by a male chauvinist culture.

Neither, it turned out, could Alice. She belonged to a long tradition of what are now called difference feminists, who believe that women must have equal rights and power not just in spite of but in part because of the fundamental differences. Others in this camp include Carol Gilligan, the famous psychologist who argued that women carry out moral reasoning with a greater emphasis on care, and make different judgments as a result.

My encounters with Alice made me realize that I was a difference feminist too. I had gone to demonstrations in the ‘60s and ‘70s to support women’s rights, but I had also written that sex differences in physical aggression are a cross-cultural universal for biological reasons. Therefore, I argued, the world will be safer when women have as much or more power than men.

I don’t say that Alice would support this line of reasoning, but she did tell her fellow feminists and the professional world of sociology that men and women are fundamentally different. Her courage in doing that drew considerable fire at the time, and the message I took from her counsel was that difference is perfectly compatible with equality.

The charge of our committee was to consider the implications of biology for parenting and offspring development, and we had a series of meetings with experts who tried to shed light on this newly born, or perhaps newly reborn subject. Alice and Jane helped edit a series of books on various aspects of the committee’s work and I was proud to contribute to a couple of them.

But Alice’s presence and leadership was key. On the one hand, conservatives resented her because she championed the rights of women, and some men in academia who considered themselves liberals couldn’t abide how outspoken she was about the domination of universities by men. On the other hand, she never thought that men and women are the same.

Although she may not have said it in so many words, I learned from her something I think is still true: that the most underrepresented minority in the academic world is mothers. Alice in her writings and speeches emphasized that women’s lives have a different time course than men’s, and that it is essential for not only colleges and universities but all institutions in our society to recognize that.

In part because of her arguments, Hillary Clinton, Sandra Day O’Connor, Ruth Ginsberg, and many others were able to be mothers and also to lead at the highest levels, because it wasn’t expected that their resumés would look just like men’s.

Alice and her husband, Peter Rossi, conducted one of the only studies of behavior and the menstrual cycle that included men as control subjects. I recall two findings: first, weekends made a heck of a bigger impact on women’s behavior than the menstrual cycle did. Second, men had the same average number of days per month of moodiness and discomfort–they just came randomly, while the women’s bad days were tied to menses.

I still quote this study to my students. I have to tell them that once upon a time menstruation was used as an excuse to keep women out of certain professions, since their behavior became supposedly erratic a few days a month. The reason my students don’t know this is that Alice Rossi and a handful of other women erased that stupid idea from our culture’s consciousness before most of them were born.

So I explain, and then I ask them: Would you rather have your airplane or your country piloted by someone who has a few days a month of moodiness and discomfort that arrive without warning, or someone with the same number of bad days that come around like clockwork? Even with freshmen, I don’t have to wait for an answer.

But in the same wise and effective lifetime, Alice managed to argue and teach that men and women can be both different and equal, and that in discussing gender, biology does not have to be banned from our vocabulary. She was much admired, is fondly remembered, and will be missed.