…are science deniers:

Ms. Benenson explains that there’s an “inherent conflict in unrelated females’ relations with one another.” They very much want one another’s support—as coalition partners and for help with childcare—but “they must invest first and foremost in their families.” In fact, because we are driven to pass on our own genes or at least those of people closely related to us, it really doesn’t make evolutionary sense for a woman to invest in an unrelated woman, except as a form of self-protection.

How this plays out among women leads to some “very confusing” (and often ugly) relationships, with women as covert competitors, using tools including gossip and social exclusion to push down other women, especially any who dare to stand out.

Men, on the other hand, are direct and domineering with one another from boyhood on in a way that women are not. Men come together in groups, while women form dyads—groups of two. Men love competition and contests to see who’s best, whereas women get insulted if one woman seems to be asserting herself as better than the others.

In fact, research finds that women bond through sharing their failures and vulnerabilities—an essential bit of information that helps explain what Sandberg merely laments: women’s not proclaiming their greatness in the workplace and not finding it natural to just march right up and “sit at the table.”

Although Ms. Sandberg, like other business advice writers, repeats the stereotype of women as “communal,” it is actually men who evolved to be cooperators in a way that women, ever-vigilant that another woman might get one over on them, did not. When men aren’t fighting each another, they are quick to band together against a common enemy. Or, after kicking each other’s asses, they’ll go and have a beer.

Sure, it’s 2015, and we’re marching through the workplace with iPhones instead of pawing in the underbrush for berries, but this evolved psychology is still driving us, and it’s to the detriment of the women who read Ms. Sandberg’s book that it is ignored instead of taken into account.

People should be treated as individuals, not members of groups, but it’s foolish to deny the intrinsic differences between men and women. In a sense, they’re almost different symbiotic species.