Chimpanzees vs. Bonobos: What’s the Difference?

Chimpanzees and bonobos are amazingly similar to us—and each other: The two species of great ape have genomes that are nearly the same as ours, and they resemble each other to the point that bonobos were once called “pygmy chimpanzees.” But chimps and bonobos also have some not-so-subtle differences. Let’s take a look.

Chimp vs. Bonobo Cheat Sheet

Size and Appearance

The easiest way to spot a bonobo (Pan paniscus) is by their straight black hair, which lies flat on their heads with a distinct middle part like Alfalfa’s in The Little Rascals. They’re born with hairless black faces and pink lips that they retain through adulthood. In contrast, chimpanzees (Pan troglodytes) are born with pink, hairless faces and dark hair, both of which get darker as they get older. 

Bonobos are about the same size as chimps but are more slender and lithe, with longer legs and smaller, rounder heads. Chimps have a heavier build and a more pronounced brow ridge. 

Behavior and Personality

Both chimps and bonobos live in fission-fusion societies, meaning that the main groups of about 20 to 80 members will often split up into smaller groups for part of a year for a particular purpose, such as searching for food. The smaller groups will then rejoin the larger group. 

These apes, though, are better known for their stark differences in behavior and personality.  Bonobo society is matriarchal, while males dominate chimpanzee society. Bonobos will share resources and bond with members of other groups; they often employ sex as a way of quelling conflict and bonding. Chimps are extremely territorial—they patrol the borders of their domains and have violent conflicts with outsiders.

Bonobos have a reputation as the peace-loving “hippie” ape, but they can be aggressive, too. Male bonobos will fight among themselves even more than chimps do and females will quell trouble with physical force.

Diet

Chimps and bonobos both eat a lot of fruit and plants, which helps distribute seeds throughout their forested habitats. Fruit is the majority of the bonobo diet and scientists long believed they weren’t meat eaters, but, like chimpanzees, they will eat insects and earthworms, insect larvae, eggs, small mammals, and even other primates.

Chimpanzees in Guinea have been observed drinking palm wine, the naturally fermented sap of raffia palms. According to a 2015 paper in Royal Society Open Science, the chimps fold leaves into a cup to sip the liquid.

Evolution

Chimpanzees and bonobos split into different species about 1.7 million years ago. The widely accepted hypothesis is that their common ancestor lived north of the Congo River.

A 2015 study in Evolutionary Anthropology examined the origins of the river—which is the world’s deepest with a maximum depth of 720 feet—and its role in primate evolution. Researchers looked at river sediments and suggested that, at times when the river’s flow decreased, some brave individuals of the common ancestor species were able to migrate to the other side. Then, they were permanently separated from the larger group when the river rose again. (Modern chimps and bonobos are poor swimmers.)

The group that crossed the river evolved into bonobos. Life was pretty breezy on the south side. There was plenty of uninhabited rainforest and food was abundant. Females developed social networks that ensured their mutual safety from pushy males. Skills like cooperation and sociability were able to flourish. A 2012 study on bonobo brains found more gray matter in the regions that perceive distress in others and one’s self, and larger pathways to aggression control and biases against harming others.

The group that didn’t venture forth ended up evolving into chimpanzees, and they had a tougher go of it. Food was less plentiful and there were gorillas to fight against for territory. Strength and aggression were valuable survival traits.

Today, the International Union for the Conservation of Nature (IUCN) considers both of our closest relatives endangered with decreasing populations. The primates are poached and hunted for meat, and they must contend with an environment altered for human uses like mining, ranching, and housing. Bonobos in particular are in danger from from civil unrest and military activity in the Democratic Republic of Congo.

Can chimps and bonobos interbreed?

Chimps and bonobos are known to interbreed in captivity, and a study published in 2016 in the journal Science found that it’s happened in the past among wild populations. Scientists studying the genomes of 75 wild bonobos and chimpanzees from various regions of Africa found that there was likely a crossover of genes between 200,000 to 550,000 years ago, and another less than 200,000 years ago, leaving a small (less than 1 percent) contribution of bonobo genes in the central African chimpanzee genome.

Are chimps or bonobos closer to humans?

Bonobos share about 99.6 percent of their genome with chimpanzees and 98.7 percent with humans, while chimps share 98.8 percent of their genome with humans. 

A 2021 paper in the journal Nature showed, via new bonobo genomic data that allowed comparison with the genomes of other ape species, that 2.52 percent of the human genome is more similar to bonobos than chimps, and 2.55 percent is more similar to chimps than bonobos. Chimpanzees thus have a very slight edge over bonobos as our closest living relatives.

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