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Valerie Curtis, Ph.D.

Valerie A. Curtis Ph.D.

Disgust Has Us in Its Grip

Five things disgust tells us about ourselves

Disgust is one of our most powerful emotions, it drives what we do in the privacy of our homes, as well as out in the world. It drives our most intimate habits, our social interactions and our moral judgement. Yet it’s still not very well understood. That’s a pity, because disgust can teach us a lot about ourselves. Here’s five things we can learn from disgust:

1. Brains are for behaviour.

You may think that your brain is for thinking, for cogitating, for solving problems. But thinking is only the icing on the cake. Brains evolved because they made the animals that were our ancestors behave in ways that got them what they needed. One fundamental need of all animals is to not get eaten. Hence all animals have behavioural strategies to keep safe from predators. The brain system that drives such behaviour is called FEAR. But it’s not just predators that want to eat you. Billions of microbes and parasites want a free meal and a free ride out of you too. The brain system that keeps us away from these micro-predators is called DISGUST. Our brains instinctively recognise yucky, smelly, sticky, contaminated stuff as potentially risky and the disgust system in the brain dictates the appropriate behaviour: ‘Don’t look, don’t touch, don’t eat!’ Brains evolved to make us do such tasks (others include nurturing, hoarding, pair bonding and status seeking) without invoking conscious, rational calculation. Our brains are for behaviour.

2. You are disgusting.

Unpleasant as it may be to contemplate, you are a walking mass of infectious material. You are home to billions of microbes, millions of worms and plenty of other parasitic creatures. You are therefore a disease threat to other people and, hence, you are disgusting. (So am I!). But being disgusting is a bit of a problem for a social species like ourselves. How to get all the benefits of cooperating with friends and acquaintances, alike, without turning them off you? The answer is simple – good manners. You learnt from your Mom and your mates at an early age not to wear stinky clothes, to breathe in someone’s face, to wee in their front room or to offer them your dirty towel. If you did they’d be disgusted, and you’d lose an ally. Because you are disgusting you have good manners and that’s how you tip the balance between being disgusting and being accepted as a member of society.

3. Your ancestors control you

Though disgust may seem rational, it’s not really under conscious control. Try this experiment. Take a glass, spit in it, put it down, pick it up again and now drink it. Difficult? Actually, it’s almost impossible. Rationally, you know that what’s in the glass is the same as what’s in your mouth, slimy saliva with all its millions of viruses and bacteria. But the voices of your ancient ancestors tell you that all spit is bad to drink (because it may have come from someone else). The same applies to all of our body contents. Whilst they are inside us we can just about tolerate them, but once evacuated or spilt, they become disgusting. The ancestral voice of caution tells us to stay away – because that’s what got the genes of our ancestors where they are today – in us. Ancestors with low disgust thresholds got sick and passed on fewer genes. Ancestors with high disgust sensitivity got to be our ancestors. That ancient ancestral brain is still in control.

4. What feelings are for

If asked what disgust is, most people would say it’s a feeling. And indeed the feeling of nausea, crawling skin, clammy hands and wanting to recoil seem to define disgust. And because there is a feeling of disgust we say that disgust is an emotion. But I think that, being a rather anthropocentric species, we’ve got the story backwards. All animals need to avoid pathogenic organisms, hence all animals needed a brain system to drive disease-avoidant behaviour. Nematodes, frogs, swallows, badgers, mice and monkeys all avoid sick cousins, practice hygiene and prefer pathogen-free food. All animals, then, have disgust systems, since without them parasites would have driven them extinct. But do all animals feel disgust? Feelings are probably unique to those higher primates that can do executive control of behaviour, that have the ability to imagine the future and work out what it would feel like. Only humans can decide that they’ll put the food away in the fridge now, because they can imagine, and feel how disgusting the food will become after three days left in a warm room. Feelings are how we humans tap into the wisdom of our ancestors, and how we employ that wisdom in feeling our way through planning for the future.

5. Why we have emotions

Disgust is an emotion. It’s a brain system that makes us behave in ways that get us what we need. Other emotions include fear (to keep us away from predators-see above), nurture (to make us care for kids so as to raise them), love (to make us pair-bond so as to raise kids), affiliation (to make us cleave to groups and so get the social benefits) and justice (to make us want to punish bad deeds). In my view feelings are not what define emotions. (For example happiness and sadness are feelings but they are general and don’t help us meet a specific evolved need, hence, they should not be classed as emotions). Comprehending that emotions like disgust evolved to make our ancestors behave in ways that were good for their genes should help all of us to better understand our feelings, our emotions, where they come from and who we are.

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About the Author

Valerie Curtis, Ph.D.

Valerie Curtis, Ph.D., is a Disgustologist and Director of the Hygiene Centre at London School of Hygiene and Tropical Medicine