Bonobos have human-like sense of disgust, researchers find

June 4, 2018, Kyoto University

Even bonobos lose their appetites with enough if they experience disgust. These primates, known for their liberal attitudes toward sex, are also generally open-minded when it comes to new foods—as long as it's is clean.

Researchers from Kyoto University's Primate Research Institute have now found that a bonobo's curiosity transforms into caution when food is presented with or near feces, soil, or bad smells. Their study was published in the journal Philosophical Transactions of the Royal Society B.

In nature, parasites and pathogens are everywhere, and can enter the body along with food. Humans have therefore adapted sensitivity to the signs of such pathogens.

"Current studies suggest that animals evolved a system to protect against such threats, now known as the adaptive system of disgust," says Cecile Sarabian, lead author of the study. "For example, bodily fluids are universal disgust elicitors in humans, and recently, we published evidence that the same reaction exists in our primate cousins."

In a series of experiments, bonobos were presented with different food choices involving novel food items: foods contaminated with feces or soil; chains of food items linked to a contaminant; previously contaminated food; or only the odors of feces or rotting food.

Although bonobos happily gobbled up clean food, they steadfastly avoided anything contaminated. Moreover, their sensitivity to contamination risk seemed to wane the farther away a food item was located from the source of contamination.

Read more at: 

What grosses out a chimpanzee? The origins of disgust

Origins of disgust

Date:  November 17, 2017

Source:  Kyoto University

Chimps show increased latencies to feed, and tendencies to maintain greater distances from possible contaminants and/or outright refusals to consume food in test conditions, hinting at the origins of disgust in humans.

Chimpanzees do some pretty disgusting things.

In their natural habitats, chimpanzees are known to pick up seeds from feces and re-ingest them. In captivity, some practice coprophagy: the deliberate ingestion of feces. These behaviors usually involve their own fecal matter, or that of their closest family members. If presented with feces and other bodily fluids from others, however, that's an entirely different story.

In 2015, researchers from Kyoto University's Primate Research Institute went to the Primate Center at the 'Centre International de Recherches Médicales de Franceville' (CIRMF) in Gabon to test whether chimpanzees are grossed out by some of the same things as humans, particularly those that are sources of infectious disease.

Avoiding biological contaminants is a well-known manifestation of the adaptive system of disgust. In theory, animals evolved with this system to protect themselves from pathogens and parasites, which are often associated with media or substrates that invoke our sense of disgust. For example, bodily products are universal disgust elicitors in humans, but until now we did not know whether they also elicit similar reactions in our primate cousins.

In a new study published in Royal Society Open Science, researchers found evidence that exposure to biological contaminants -- ie feces, blood, semen -- via vision, smell, and touch, influences feeding choices even in chimpanzees.

Read on