Here's what complex primate societies can teach us about sex and gender

However, could studying our closest relatives really help us answer the perplexing questions surrounding sex and gender in humans? After all, we've evolved significantly since our lineage split from chimps and bonobos. And, as de Waal argues in his book, there is no “simple answer”.

Reintroducing sex back into gender

First, we need to define "sex" and "gender." Sex primarily refers to biological characteristics that are associated with our physical bodies; it’s a matter of gene expression, chromosomes, hormones, and anatomy. Although sex is not a perfect binary — de Waal stated in an interview with IE that it is “approximately binary” — it is certainly simpler than gender. 

Gender is multifaceted and somewhat abstract in comparison, as no one can really agree on what it means. The term "gender" refers to the socially constructed roles, behaviors, expressions, and identity which are influenced by culture. De Waal explained to IE that gender is a “spectrum”, writing in his book that “gender resists division into two neat categories and is best viewed as a spectrum that runs smoothly from feminine to masculine and all sorts of mixtures in between.” 

In a sense, Different can be read as an attempt to reintroduce sex back into gender, as gender has long been regarded as a purely social construct by many people, according to de Waal, and discussion of inborn sex differences was frowned upon.

Humans, chimpanzees, and bonobos

In his attempt to discover more about gender and identity and investigate the traits that humans recognize as uniquely masculine and feminine, de Waal studies chimps, a male-dominant species, and bonobos, a female-dominent species.

Humans are somewhere between chimps and bonobos in terms of evolution, having diverged from our common ancestor between around six and eight million years ago. We not only share around 99 percent of our DNA with these other primates, but we also "share our socio-emotional makeup", according to de Waal. 

Despite this closeness, however, in popular imagination, chimps are commonly depicted as violent and territorial, whereas bonobos are depicted as indiscriminately sexual and pacifist. Adult male chimpanzees are typically aggressive, domineering, and status-seeking, whereas adult females are less political and less violent. Meanwhile, female bonobos exert social control — with males less violent on average than male chimps — by forming strong coalitions. Sexual behavior, including same-sex sexual behavior, is incredibly commong among female bonobos, as they appear to use sex frequently to help reduce social tensions and form social bonds.

In the book, de Waal starts by comparing how human boys and girls play in contrast to young chimps. He disputes the notion that boys and girls play differently simply because of their upbringing — he describes in the book how young chimps exhibit similar differences, such as males loving roughhousing while females frequently pretending to carry infants.

Primates have rich cultures, and de Waal argues that young primates develop their gender roles in much the same way that customs are passed down through generations. Young chimps look to adults and mimic their behavior, with young males preferring to learn from older males, according to de Waal.

This would suggest that the behaviors of male and female primates aren’t all that rigid, and that under some circumstances, they could start acting in ways one would typically expect from the other sex, indicating that biology doesn’t necessarily support the gender roles we assign to “masculine” and “feminine” in our societies. While humans and other primates share some behavioral differences, de Waal writes that biology provides no justification for existing gender inequalities.

What apes can teach us

To build a picture of the complexities of sex and social behavior in our relatives, de Waal paints enthralling descriptions of the apes, bringing them to life on the pages. You find yourself imagining the colorful life of Princess Mimi, a bonobo who was raised in a human home, or the gay capuchin monkey Lonnie, who was fully integrated into his colony. It's impossible to not be enamored by Mama, the wise kingmaker among chimps who was deeply respected and loved by her colony, or to turn the pages in a hurry to learn more about the rhesus macaque love triangle of Orange, Dandy, and Mr. Spickles.

One of the stories that stuck with me the most was about Donna, a gender-nonconforming chimp. Donna is an alpha female chimpanzee, who acted "more like a young male", de Waal explained to IE.  "At the age of three, she liked to wrestle just like the adult males. Typically, the young females don't do that."

Donna showed no interest in mating and eventually grew into a female who looked like a male with big shoulders and a big head. While de Waal refrains from calling her a "trans ape" because we can't know how she perceived her gender, he speculates in the book that she appeared to have a gender identity that contradicts her ostensible biology and that her behavior could be related to hormonal levels that correspond more to the male sex than to female. 

Overall, it's difficult to tell from Different how much evolutionary history shaped gender before and after our split from our fellow primates, and exactly how much of our behavior is genetic, hormonal, or culturally driven. While the topic is a tough one to crack, one thing is certain: de Waal's primate observations which he uses to discuss gender are intriguing and eye opening. Through these examples, the book does three things at once: It brings the readers closer to primates, defamiliarizes gender, and then reorients it, offering a thought-provoking approach to the ongoing discussion of the balance between nature and nurture as well as where sex and gender roles fit in.

“Most people have this cliche in their mind that monkeys are run by a male boss who orders everyone around and has female slaves. They think that that's how primates are organized, and this is often used to defend inequality in human society. I think that picture is totally wrong,” de Waal said to IE.

“First of all, we are not closely related to monkeys, we are closely related to apes. The two apes that we are closest to are chimpanzees and bonobos, and the fact that one is dominated by males and the other one is dominated by females makes it immediately a more complex story. One thing that I hope people can get away from my book is that this picture of natural male dominance in society is made up by people. I don't think it corresponds with what I, as a primatologist, would say is the rule.”