Sex and gender never used to be controversial. There were two sexes — men were male, and women were female — whilst gender was used to classify foreign nouns. In recent years the furious dispute over once settled questions, for example the meaning of the word “woman”, has divided society and flummoxed leading politicians. Anyone can have an opinion, but the truth is still out there. Sex and Gender: a Contemporary Reader, a new book edited by Professors Alice Sullivan and Selina Todd, provides answers that are rooted in evidence.

The editors have amassed an impressive slate of academics, each speaking from positions of expertise in their own disciplines. Biologists Emma Hilton and Colin Wright conclude that “the most prevalent mechanism of reproduction in complex species has stabilised on a binary system of differential gamete types and the subsequent evolution of body types around this binary system”.

In the next chapter, neuroscientist Professor Sophie Scott discusses the differences between male brains and female brains. Is it possible to be born with a male brain in a female body? Whilst Scott accepts that this could be “a useful metaphor”, she notes that male brains are bigger whilst female brains have “proportionally more grey matter”. On that metric, transwomen have brains closer in size to males than females.

Like her co-writers, Scott backs up her claims with references to peer-reviewed articles. Evidence, examples and citations of papers in academic journals support each one of the 15 chapters in the book. That, and the style, is typical of academic writing. The book is not an easy read, therefore, but it drills down to the truth — something that has been too often overlooked in the sex-and-gender debate.

A broad range of issues is covered. Philosopher Kathleen Stock asks the question, “Is Womanhood a social fact?” Sixteen pages later, she concluded that, “Prolonged examination of this claim has established no good reason to agree. Womanhood is a natural fact if any is” [my emphasis]. Next, Jane Clare Jones discusses the history of sex denial. The idea that we all have a gender identity, which is somehow more important than biological sex when distinguishing men from women, is a recent development. Jones discusses the impact on women — the biological kind. She concludes, “Sex denial [undermines] the concepts needed to describe women’s oppression and politically organise to challenge it.”

Denial of sex negatively impacts women, but the deleterious effect on children and their development through adolescence has been shocking. In a world that has become ever more concerned with keeping young people safe, some children have been subjected to experimental and uncontrolled experiments. Their puberty has been disrupted without any knowledge of the long-term prognosis.

Michael Biggs, whose research was central to Bell and Mrs A v Tavistock 2020 — the landmark judicial review that curtailed the use of puberty blockers in England and Wales — covers the technology of puberty suppression. It’s a grim read as Biggs discusses the literature. “Stopping sexual development meant that the penis did not grow”, and so “the genital tissue available for vaginoplasty may be less than optimal”. That astonishing understatement came straight from the Journal of Sexual Medicine. Like his co-writers, Biggs goes beyond a review of the literature and draws his own inferences. These are uncharted waters in many respects. He concludes his chapter: “it is too soon to tell whether puberty suppression will go the way of lobotomy or whether it will be one step towards a transhumanist future of self-fabrication through biotechnology.”

Shereen Benjamin — a senior lecturer in primary education — discusses schools, feminism and gender identity theory. Susan Matthews, formerly a reader in English Literature, considers how gender has been cast in children’s literature over the past fifty years. She laments that, “The fascination with the gender-bending figure of the ‘boy in a dress’ was recast as the trans child who knows their own gender even before they can speak”.

The editors have also been busy in their own chapters, drawing from their own areas of research. Selina Todd, a historian specialising in the history of women, feminism and the working class in modern Britain, analysed sex and gender in second wave feminism. Her colleague Alice Sullivan, from a rather different background in sociology, collaborates with policy experts Kath Murray and Lisa MacKenzie to explain why we need data on sex.

As a scientist myself, I would argue that is the truth

Professors of law and criminology analyse the impact of sex and gender on the law and the criminal justice system, whilst Cathy Devine — expert in the human rights of girls and women in sport — looks at the impact of sex and gender in sport. Lisa Littman, whose paper on ROGD (Rapid Onset Gender Dysphoria) opens up the phenomenon of teenage girls suddenly adopting transgender identities to a wider audience, looks at the trajectories of gender dysphoric youth.

These authors have written extensively, and each could no doubt have produced an entire thesis on their zones of expertise. By bringing them together, and presumably imposing a word count, Sullivan and Todd have created a comprehensive handbook that is far more accessible to the general reader.

It is hard going in places — the writing is thoroughly academic — but the arguments are clear. It certainly answers the question, “what do experts think about sex and gender in their own fields of expertise”. It is important to note, however, that the book leans to one side of the debate over sex and gender. According to the editors, “The scholars in this volume share a broad understanding of sex and gender.” Specifically, “sex is biological, immutable and binary”. As a scientist myself, I would argue that is the truth, and the truth is the best foundation for anyone’s arguments.

The paperback and ebook are currently both on sale below £30 so this resource is accessible in more ways than one.