A Google engineer has been fired after writing a memo asserting that biological differences between men and women are responsible for the tech industry's gender gap.

"We need to stop assuming that gender gaps imply sexism," James Damore wrote in the manifesto, which was first reported by Vice's Motherboard and later released in full by Gizmodo.

The 10-page document criticises Google initiatives aimed at increasing gender and racial diversity, and argues that Google should focus more on "ideological diversity" to make conservatives more comfortable in the company's work environment.

In response, Google CEO Sundar Pichai cut his vacation short and wrote a memo criticising Damore's manifesto for advancing harmful gender stereotypes. "To suggest a group of our colleagues have traits that make them less biologically suited to that work is offensive and not OK," Pichai wrote.

Experts have been quick to cite numerous scientific meta-analyses of differences between the sexes, most of which suggest that men and women are alike in terms of personality and cognitive ability.

Here are the specific claims Damore made in his manifesto, and the real science behind them.

Biological gender differences

Although some differences between men and women have been observed by scientists, they are mostly physical ones. Current research generally does not find evidence that variations in preferences, psychology, or personality stem from genetic or biological factors. Rather, they're primarily attributed to culture and socialisation.

In his manifesto, however, Damore suggested the gender differences he lists do have biological components. One justification he gives for this belief is that the differences he mentions are "what we would predict from an evolutionary psychology perspective" and are "universal across human cultures."

Damore didn't cite any sources to back up his reasoning. However, a 2001 analysis of responses to a prominent personality inventory test found that "contrary to predictions from evolutionary theory, the magnitude of gender differences varied across cultures" - a direct contradiction to his argument.

A strong 'interest in people rather than things'

One of the main biological differences between men and women, according to Damore, is that women are more open to feelings and "have a stronger interest in people rather than things."

He went on to suggest: "These two differences in part explain why women relatively prefer jobs in social or artistic areas. More men may like coding because it requires systemising."

Throughout his memo, Damore linked to many Wikipedia pages as justification for his claims - but neither news media organisations nor scientists accept Wikipedia as a credible source of information, especially when used in policy recommendations.

To back up the "people over things" hypothesis, Damore cited a study published in the journal Social and Personality Psychology Compass in 2010; however, that work never suggests that the gender differences it lists have a proven biological basis.

In fact, the study says the opposite: "Although most biologic scientists accept that sexual selection has led to sex differences in physical traits such as height, musculature, and fat distributions, many social scientists are sceptical about the role of sexual selection in generating psychological gender differences."

A 2000 review of 10 studies related to gender differences in empathy also suggests men and women don't have innate differences in this area. The researchers found that such distinctions were only present in situations where the subjects were "aware that they are being evaluated on an empathy-relevant dimension" or in which "empathy-relevant gender-role expectations or obligations are made salient."

In other words, differences had to do with how people responded to expectations of them, not any inherent abilities.

Adam Grant, a professor at University of Pennsylvania's Wharton School, has also highlighted the fact that differences between men and women's professional preferences are not genetically determined.

"The data on occupational interests do reveal strong male preferences for working with things and strong female preferences for working with people," Grant wrote in a LinkedIn essay responding to Damore's claims.

"But they also reveal that men and women are equally interested in working with data."

A tendency towards 'gregariousness rather than assertiveness'

In the memo, Damore suggested that women are biologically prone to express their extraversion as gregariousness instead of assertiveness, and to be more agreeable than men.

That difference, he claims, "leads to women generally having a harder time negotiating salary, asking for raises, speaking up, and leading."

Again, Damore didn't cite any evidence for this part of his argument. A 2005 analysis of 46 meta-analyses of gender differences suggests it's false.

According to the American Psychological Association, one experiment in that analysis involved participants who were told that they would not be identified as male or female.

Under those conditions, "none conformed to stereotypes about their sex when given the chance to be aggressive." The researchers found the opposite to be true, in fact: "women were more aggressive and men were more passive," they wrote.

And a meta-analysis of leadership effectiveness published in 2014 suggests that when it comes to others' evaluations of leaders (as opposed to the leader's own perception), "women are rated as significantly more effective than men."

When looking at self-ratings, however, "men rate themselves as significantly more effective than women rate themselves."

That suggests that context and learned expectations are responsible for some observed gender disparities.

Neuroticism and anxiety

Damore also suggested that women are biologically prone to feel higher levels of stress and anxiety, and posited that difference might contribute "to the lower number of women in high stress jobs."

The only source he gave for this information is Wikipedia. However, the misconception might have stemmed from analyses of the Revised NEO Personality inventory (the prominent personality test mentioned above).

On the test, according to a 2001 secondary analysis, women reported themselves to be higher in neuroticism.

But those responses are based purely on self-perception (which is heavily influenced by social and cultural factors) so it'd be problematic to consider that a biological difference.

A search for work-life balance instead of status

"Women on average look for more work-life balance while men have a higher drive for status on average," Damore wrote.

As evidence for this, he cited a 2006 paper published in the British Journal of Guidance and Counseling.

That article highlights the fact that more women value a balance between their professional and home lives than men. It also suggests that men are more likely to make their careers their first priority.

However, nowhere does that paper suggest that these preferences come from biological or evolutionary differences between the sexes.

In fact, it makes this caveat: "They are differences of degree, with large overlaps between men and women.

They are not fundamental qualitative differences, as often argued in the past in order to entirely exclude women from 'male' occupations such as management, the military and the professions."

Gender expectations of men

Damore does make a couple of valid points about the gender expectations of men, and the way these might contribute to the tech industry's gender gap.

He suggested that because men are often judged based on their status in the professional world, that pushes "many men into these higher paying, less satisfying jobs for the status that they entail."

Furthermore, Damore noted that "men are still very much tied to the male gender role," and wrote that allowing men to express traits or pursue goals that are traditionally thought of as "feminine" would help alleviate some of the gender-gap problems.

Although he doesn't cite any sources for these claims either, it seems logical that gender expectations and stereotypes are partially responsible for the types of roles men seek out in the workplace.

Pichai also acknowledged the validity of Damore's complaints about perceived intolerance of conservative viewpoints among Google's employees.

"There are co-workers who are questioning whether they can safely express their views in the workplace (especially those with a minority viewpoint)," the CEO wrote in his statement. "They too feel under threat, and that is also not OK."

Damore's views, however, were not the reason he was fired - rather, it was because portions of his manifesto violated Google's code of conduct.

According to Reuters, Damore is now pursuing legal action against Google, though labour law experts suggest his case could be an uphill battle.

This article was originally published by Business Insider.

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