Image: the cover of the book is a black background with large words- sex is a spectrum- colored in rainbow gradient positioned on their side (extending vertically rather than horizontally.) in small white letters between the words is "the biological limits of the biggest" and "agustín fuentes"
I come from a generation wherein discussions of gender often highlighted the importance of differentiating gender from sex. In these conversations we would often discuss diversity within gender, while also at least partially conceding that sex was binary, with the exception of an often ill described or tokenizing inclusion of intersex individuals. Many of us knew things were more complicated, but we needed a simplistic argument in order to fight for our rights, be they feminist, lgbq, trans rights, etc. More recent understandings of biology have shown that sex is a lot more variable than once assumed. This made sense to me, but I often didn't have the education or ability to confidently argue things one way or the other. This has become especially difficult with how algorithms have become so horrifically bad at nudging folks towards accurate information, making one's attempt at research through a highly monetized search engine often futile. Furthermore, much of the discussion around sex is dominated by archaic patriarchal structures within sciences or by bad faith actors with no scientific credentials who defend dated and debunked ideas about sex and gender. I went into Agustín Fuentes' book Sex is a Spectrum with high hopes but realistic expectations. This book surpassed both of them.
Fuentes is a biological anthropologist and primatologist who writes in extremely enlightening ways on these topics. I enjoy thinking and learning about evolution, including how it affects the human species psychologically and anthropologically. Unfortunately, I often go into readings with gritted teeth, wondering if I'm going to encounter something useful or something ridiculous. Some ideas of what constitutes evolutionary adaptation/advantage are dominated by people with highly archaic, patriarchal, racist, and other oppressive ways of thinking. Examples include men who argue that rape is an biological imperative of men, men who argue that the reason violent and abusive men exist is because women choose them for procreation, and a wide gamut of racist and xenophobic beliefs about evolutionary contributions of various peoples. Fuentes not only broke from these sorts of traditions, but brought many new ways of thinking about humans into my worldview. It was very refreshing to see someone make statements in the realms of evolutionary anthropology and psychology that both criticize more oppressive mainstream misconceptions while also bringing newer information (at least to me and mainstream thinking) to the table.
Some might expect this book, despite it's clear focus on biology, to lean on of gender/queer theory a lot, but there is very little of it therein. It is a matter of fact book about what biology, anthropology, primatology, and cultural histories tell us about sex in human beings. It is refreshingly grounded in hard science while also being accurate and honest in terms of what statements can be made with higher levels of certainly. Furthermore, Fuentes writes in a style that can actually be read by a wide audience. He also has condensed a massive amount of argument and information into a rather short book. Basically, this book is accessible and readable which feels more critical than ever given how this topic is treated in the world these days.
Fuentes hits all of the topics that I've run into or questioned myself regarding the biology and (false) binaries of sex. These include everything from primate evolution, chromosomal variation, gender expression, sex assignment at birth, secondary sex characteristics, hormonal variation, environmental and cultural influence and interaction with biology (and vice versa,) behavioral differences between sexes and genders, diversity within sexes and genders in a variety of categories, and so on.
Within these topics, Fuentes' makes many well supported arguments. There are multiple ways that sex binaries are defined, ranging from chromosomal variation (which most of us never know we have,) physical growth and development, behavior and psychology, expression (or not) of bodily functions, and so on that very rarely fit into two distinct categories. Intersex individuals are not aberrations or afterthoughts, but normal parts of human sex variation and have a wide variety of traits and expressions. Dividing humans into two binary sex categories results in reductive, inaccurate, and all around bad science and medicine due to the massive variability and overlap of attributes tied to sex. Sex and gender are biocultural (meaning culture and environment interact with and influence biology and vice versa) which causes variability across the globe. There is much variability across sex in all primate species and humans are no exception. The helplessness of human infants resulted in evolution of cooperative, (bio and non) family structure that is not in line with archaic ideas many have about gender and family. There are no "male brains" and "female brains" (an argument I have unfortunately seen some trans folks latch onto) and the variability, diversity, and overlap in brain function cannot be applied to one sex or another. There are other well argued points, but you get the picture.
It is important to state that Fuentes is not at all making the argument that there are no differences between humans of various genders and sex assignments. I found the discussion of things like aggression and violence to be particularly interesting. He does not argue that everyone is the same and that patriarchal imbalance with abuse and violence does not exist. Rather he argues that claiming that this is a purely biological trait that men are predisposed to have is dangerous and inaccurate. Cultural influence combined with a variety of factors play into this far more than human sex biology alone does.
In the last section of the book, he speaks specifically about some of the topics where folks attend to onto binary thinking the most: Sexuality, family composition, medical research and practice, cardiac disease, organ transplants, pregnancy and birth, sports (wide ranging in and of themselves,) restroom assignment, and so on. He very clearly discusses where studies have shown differences and how well we are able to say where those differences come from. You may have already heard that it's not nature versus nurture, but how these two things interact. His discussions on the biocultural nature of sex took this idea to a new level for me as his emphasis on both biological and anthropological research really shows how damaging these binary categories are in many situations.
Things in life are generally far more complex than we like to admit and sex is no exception. There are much better ways to categorize people than along and inaccurate binary. For instance, all humans have testosterone in different amount and it can be more appropriate to categorize people based on testosterone levels than on sex.
I could continue blathering on, but I will stop here because I want everyone to go read this book. An optimistic take would be that people from a variety of belief systems, if willing to open their mind just a little bit, would be able to take in this book and be changed by it. I've been changed by it.
This was also posted to my goodreads and storygraph.