We usually think of science as propelling us forward. Where would we be, after all, without the insights of Newton and Copernicus? Yet for all the progress that science has made in helping us better understand the universe, for much of history it has also held back half of humankind.

Prominent scientists have long claimed that male and female brains are fundamentally different, with women less intelligent than men. Similar attitudes persist in the public sphere as well.

The recent controversy ignited by a staff memo from James Damore, then a Google software engineer, demonstrated this. Damore argued, in part, that men and women have biological differences that help explain gender gaps in tech fields. His points were based on research that has been heavily criticized in recent years, but which recirculates every so often during conversations about discrimination and bias.

Despite the backlash, the science that underpins Damore’s memo is not new at all. Indeed, the record of bad research and scientific bias against women stretches back hundreds of years. To take a more famous example: When Charles Darwin published his theories of natural and sexual selection in the 19th century, the world was finally able to place human origins in the sweep of history, linking us to all other life on earth. What we hear about less often is just how spectacularly blinkered Darwin was when it came to women’s place in this evolutionary story.

“The chief distinction in the intellectual powers of the two sexes is [shown] by man attaining to a higher eminence, in whatever he takes up, than woman can attain — whether requiring deep thought, reason or imagination, or merely the use of the senses and hands,” Darwin wrote in his 1871 groundbreaking book "The Descent of Man."

“Thus man has ultimately become superior to woman,” he added.

Darwin’s belief was that women were less evolved than men helped explain the gender imbalances he saw around him. As far as he could tell, there were no great female scientists, artists or political leaders. Women were generally subservient and confined to the home. What other reason could there be for this phenomenon but biology?

It wasn’t just Darwin who held this view. As I explore in my new book, "Inferior: How Science Got Women Wrong and the New Research That’s Rewriting the Story," such opinions were enthusiastically shared by many leading male Victorian scientists. Some stated that women were less intelligent because they had smaller brains. Others, that too much intellectual activity might damage a woman’s reproductive ability.

Darwin’s belief was that women were less evolved than men helped explain the gender imbalances he saw around him.

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Darwin and his male peers, we now see, were blinkered by prejudice. The genius they applied to their work was oddly laid aside when it came to thinking about women. If the sexes appeared to be unequal, there were plenty of explanations that had nothing to do with biology.

Most male scientists conveniently chose to ignore that women were actively denied access to higher education (the University of Oxford, my alma mater, didn’t admit women as full members until 1920); that they were excluded from the great scientific academies (Marie Curie was denied membership into France’s Academy of Sciences in 1911 — despite being a Nobel laureate); and, of course, that they were banned from voting or holding public office. In Darwin’s time, a married woman wasn't even allowed to own property.

Unfortunately, while society has moved past many outdated Victorian mindsets, the legacy of sexism in science remains. Just this summer, the journal Intelligence published a questionable paper claiming that women have lower IQs than men, despite a wealth of data stretching over decades that has established that there’s no average gender difference in intelligence.

A few prominent scientists continue to claim that male and female brains are fundamentally different. One University of Cambridge researcher in autism, for example, claims that male brains are generally hardwired to build and understand systems, such as computers and cars, while female brains are wired for empathy.

The unavoidable implication of research like this is that women and men are built for different roles in society: Women fundamentally are better suited to be homemakers, men to be hunters and builders.

In his 2000 book, "The Mating Mind: How Sexual Choice Shaped the Evolution of Human Nature," by Geoffrey Miller, an evolutionary psychologist at the University of New Mexico, writes: “Men write more books. Men give more lectures. Men ask more questions after lectures. Men dominate mixed-sex committee discussions.” In the same book, he states, “In the game of science … sounding sexist is not a good reason to ban a theory.”

This may be true. But political correctness isn’t the enemy — bad science is.

The implication here is that this behavior is biological, and not related to the way society {has treated or continues to} treats women. But context is key. For example, it is not particularly controversial to say, as Damore did, that men and women have been shown to think differently. But as Wired writers Megan Molteni and Adam Rogers note, “the issue is the extent of the difference (and what causes it).” In making his case, Damore cited research by a psychologist, David Schmitt. When reached by Wired, Schmitt argued that Damore had overstated and misinterpreted his data.

While society has moved past many outdated Victorian mindsets, the legacy of sexism in science remains.

Today, especially as female researchers enter the sciences in greater numbers, a new portrait of women is being drawn, both fairer and more scientifically thorough. It reveals that women and men have few psychological differences, that female hunters may have been common in our evolutionary past, and that humankind’s first inventions were likely devised by females — slings for carrying babies, for example, and digging sticks for rooting out plants and tubers.

Anthropologists studying hunter-gatherer societies have documented how remarkably egalitarian many of them tend to be, laying to rest the old-fashioned "Flintstones" model of early humans, in which men are central to acquiring food and to invention.

But even as sexist bias in scientific research is slowly being called out, there is a long way to go. Whatever illusions the scientific establishment may hold, there is still entrenched prejudice against women in some quarters.

Moving forward, scientists must do better in understanding that their work sits inside a cultural and historical context. If women have been misunderstood, it is in large part because researchers failed to see how their lives, opportunities and freedoms were constrained by society — not biology. This isn’t a simple issue of nature vs. nurture so much as an acknowledgement that nurture, especially where psychology is concerned, can also greatly influence nature.

In a passionate letter to Darwin in 1881, Caroline Kennard, a member of the women’s movement in Boston, put it best: “Let the ‘environment’ of women be similar to that of men and with his opportunities, before she be fairly judged, intellectually his inferior, please.”

Indeed this is an important warning to us all. Damore has continued to insist that his conclusions are correct. This reveals that the public, too, must approach science with a more critical eye. Every piece of published research does not represent an unmitigated truth. Scientists get things wrong — indeed, a crucial part of the process of science is making mistakes and correcting them.

When humans study humans, it’s easy for bias to creep in. After all, it’s a subject close to all our hearts. Darwin’s big lesson for us is not just that humans are complicated, but that scientists are human, too.

Angela Saini is an award-winning British science journalist and broadcaster. Her latest book, "Inferior: How Science Got Women Wrong and the New Research That’s Rewriting the Story," is out now from Beacon Press.