Being a woman and a biologist, that is to say, having studied the life sciences, I am still surprised by how little I know about the biological changes that being a woman entails. Conversing with friends, we comment that no one ever explained to us what menopause really involved, as well as the associated bodily, organic, and metabolic changes. Regarding menstruation, although it may seem that it is now liberated and that everyone talks about it freely, it is also not explained what it really means for a girl's body, nor the transient and permanent changes that this biological stage implies. Dysfunctions such as endometriosis are now starting to be diagnosed and studied; regarding the effect of contraceptive hormones on our body, they have only been mentioned to us for their contraceptive effect, but not for the extent of the unnatural hormonal treatment that it represents when taken prolonged over years; nor has anyone spoken to us about the loss of ovarian reserve with age, a matter that is now increasingly present because women want to be mothers at more advanced ages. It almost seems as if women were invisible.

More than two thousand years ago, Greek medicine attributed some women's ailments to a uterus that moved through the body as if it were a restless and mischievous animal. It was believed that it could cause choking, convulsions, pain, or fainting depending on the place where it moved. It was even recommended to use pleasant or unpleasant odors to make it return to its place. Over the centuries, hysteria, a word derived from the Greek hystéra (uterus), became a label that grouped together very diverse manifestations, often interpreted based on the gender stereotypes and prejudices of each era. When medicine did not know how to explain what was happening to women, it seemed that the answer was always found in the fact of being women.

Hormones have often been used to explain any discomfort in women. But, according to psychiatrist Gemma Parramon Puig, head of the psychiatry section at Vall d'Hebron Hospital, this perspective has hidden another reality for decades: a medicine built by taking the male body as the standard and biases that have delayed diagnoses, medicalized social problems, and made women's health invisible. In "It must be the hormones (Vergara), argues that incorporating the perspective of sex and gender is essential for better medicine.

Science has not treated men and women equally. Often, with the excuse that women's hormonal cycle could distort results, clinical trials have been conducted only on men for convenience and to erroneously assume that the bodies' response was the same in both men and women. The result is that women are generally underdiagnosed and that on many occasions they receive treatment later – if they receive it –, have less access to care, and suffer more pain because their symptoms are not taken into account, because they do not fit with what men are said to feel. As Gemma Parramon, head of liaison psychiatry at Vall d'Hebron Hospital and author of the book Será por las hormonas,there are increasingly more studies that demonstrate, in different contexts, that women wait longer on public healthcare waiting lists or that there are more diagnostic delays even in diseases where it is fundamental to detect the condition in time.

As a predoctoral researcher, I study the aging of hematopoietic stem cells – the cells responsible for regenerating all our blood throughout life–. A few years ago, while observing these cells under a microscope, I noticed some strange differences between my samples. They were supposed to behave identically, as they all came from donors of the same age, but this was not the case. I remember a thought coming to my mind: "Are these donors of the same sex?". Until that moment, I had never asked myself this question. When I started reading the scientific literature, I realized this wasn't just my blind spot. For centuries, both basic research and modern medicine have operated under the premise of the "standard human": the Reference Man. This wasn't done as a conspiracy theory to exclude women from research, but out of a combination of convenience and practicality. Early medical researchers used military records of healthy male soldiers as a baseline; furthermore, scientists actively avoided studying female individuals, claiming that fluctuations in menstrual hormones would distort the data. This bias was so profound that, even in basic research, female mice were systematically excluded.

Almost a decade after closing the shop she had in Sant Andreu, Barcelona, Pilar still frequently meets neighbors in the neighborhood who stop her to remind her, gratefully, that they have half their house set up by her. "It was the family business, of electricity and spare parts, which I gradually transformed into decoration," explains this cheerful 70-year-old woman.

For years, sociologist Elisa García-Mingo has immersed herself in the study of the machosphere, online communities that spread misogynistic content, whether through ridiculing comments and messages or by asking artificial intelligence to reinvent photographs of women to undress them.