These question and more were addressed on Monday evening in a reading and interview with Peter Kappeler about his new book, "Sex and Genders' Changing Role: An Interdisciplinary Journey Through Biology, Culture, and Discrimination". The event was moderated by Stefanie Heiduck, director of the DPZ Library and the DPZ’s equal opportunity officer.
Gender and gender identity are among the most socially controversial topics of our time. Arguments often revolve around “human nature” or “biological sex.” But what does the biology actually say about this?
Peter Kappeler is head of the Department of Behavioral Ecology and Sociobiology at the German primate center. He has been researching gender relations among Madagascar’s lemurs for three decades and has also studied the significance of gender in human cultures in depth. With his book, he aims to shed light on this complex and often emotionally charged topic and bridge the gap between biology and culture.
Biologically speaking, it’s actually quite simple, explains Peter Kappeler: “In sexually reproducing species, there are two sexes. Males have small sperm cells, and females have large egg cells.” Genitals, chromosomes, and hormones are often cited in social debates to define biological sex or to justify differences between the sexes , but they are not relevant for this classification. Nor is one’s perceived gender identity. In humans, these factors mostly correspond to the gender determined based on sperm or egg cells – and sometimes they do not.
![[Translate to Englisch:] Peter Kappeler presents his new book "Geschlecht im Wandel" on sex, gender and discrimination. He is wearing a blue shirt. On the book cover you can see people of different gender and ethnicities, and the logo of Springer Publishing. Blurry houseplants are visible in the background.](/fileadmin/_processed_/2/4/csm_PXL_20260706_150445456.PORTRAIT_bf096943be.jpg "Portrait of Peter Kappeler with his new book.")
What about biological differences and dominance?
From a biological perspective, these questions are interrelated. Whether one sex dominates the other also depends on physical characteristics. To explain this, Peter Kappeler points to our relatives in the animal kingdom.
Male gorillas are on average twice as heavy as females. The females are simply physically inferior, and the social system is strongly hierarchical and male-dominated. Other closely related primates, on the other hand, live in female-dominated or egalitarian communities. This occurs primarily when there are few physical differences between the sexes or when the females employ strategies that compensate for their physical inferiority, explains the behavioral biologist. Generally speaking, if one sex is permanently physically superior, this is often reflected in the social system.
And in humans?
Aside from chromosomes and germ cells, sex differences in humans are comparatively mild and do not explain male dominance. Differences between men and women are much more culturally than biologically determined. Although some differences between the sexes can be observed, Professor Kappeler emphasizes that the sexes may not be the same, but they are equal. Discrimination against women, he says, is a purely cultural and relatively recent phenomenon in human history that is not biologically justified.
Speaking of patriarchy – how did that come about?
Not an easy question. What is clear is that the advent of agriculture fostered the accumulation of resources and power in humans.
Generally, the drive for dominance among men and male animals is fueled by the fear of spending their resources on raising another man’s children. Women don’t have this problem—they don’t have to wonder whether a child is really theirs. In humans, there’s an additional factor. Unlike, for example, female cape baboons, human women do not signal when they are ready to conceive. According to male evolutionary logic, men must therefore maintain constant control over women in order to rule out the dreaded children of uncertain paternity.
For those interested in exploring this topic further, we recommend Peter Kappeler’s book, released in 2025 by Springer Publishing. The German title is “Geschlecht im Wandel – Eine interdisziplinäre Reise durch Biologie, Kultur und Diskriminierung".
