Hate cilantro or anchovies? Evolutionary science could explain why.

Black licorice, oysters, and anchovies are the most hated foods in the U.S., according to an analysis of Instacart purchases and online surveys collected by the grocery delivery service. But many consider these foods a delicacy—so why are certain foods so divisive?

Our early human ancestors may have relied on their sense of taste to identify nutritious new foods and avoid toxins. As a result, scientists think we tend to dislike bitter foods because plant poisons taste bitter, and we tend to like sweet foods because our brains identify sweetness as glucose, a great source of energy.

But today, with our food designed, engineered, and processed to have an array of flavors, these defense mechanisms aren’t as helpful. With ultra processed foods making up over half of U.S. adults’ energy intake, easy access to tasty, energy-dense foods means our sense of taste doesn’t always guide us to the most nutritious choices.

Science is revealing that modern food aversions tend to be cues from our bodies, brains, environment, parents, and culture. Our bodies protect us from toxins, our brains learn from experience, and our surroundings shape our preferences.

How we feel shapes what we taste 

Beyond our innate positive responses to sweetness and negative responses to bitterness, we learn a lot about food from our parents, what we’re exposed to early in life, and what foods are valued in the culture we live in.

“People around the world basically learn to like what they eat,” says Julie Mennella, nutritional scientist at the Monell Chemical Senses Center in Philadelphia, beginning from what the mother eats while the baby is in the womb and breastfeeding, to the first solid foods a child eats. “They learn from modeling, what parents eat, siblings eat, peers eat,” adds Mennella.

And if mothers don’t like a food, they’re less likely to offer it to their children, says Yanina Pepino, nutritional scientist at the University of Illinois Urbana-Champaign.

The environment surrounding eating—what we see, smell, feel, and hear—shapes this learning experience too, adding to the story our brains form around certain flavors.

Listening to music while eating, for example, affects how people perceive flavor, an effect called sonic seasoning.

“Sound can change expectations, and expectations have a lot to do with disgust or preference” explains Qian Janice Wang, psychologist at the University of Copenhagen. “If your first exposure to something was in a very stressful environment… that can affect your association with it going forward.” 

The color of a room and color and texture of plates can also affect how food tastes to people. “A lot of these effects have to do with expectations: we make predictions about the food we’re going to eat from these environmental cues,” says Wang. Our bodies and brains take in and integrate all this information to create a learned experience of a certain food.

Food poisoning leads to long term aversions

Our bodies can also learn from a bad experience with a specific food. If you eat something that causes food poisoning, your body might avoid that food in the future. The brain’s memory hub communicates with the gut, creating a lasting aversion to a particular food even after the sickness has passed.

If something makes you sick, it only needs to happen once to make a lasting impression, says Pepino.

And these associations in our brains are strongly connected to flavor specifically.

Pepino points out people who have had a bad experience after binge drinking tend to later have an aversion to a specific type of alcohol—for example, saying they’ll avoid tequila, but red wine is fine.This choice avoids a certain flavor, not the alcohol that actually caused the sickness.

Taste and smell preferences coded in our DNA

Although learning can condition our flavor preferences, genetics do play some role in what foods we like and dislike.

Food preferences and aversions can both be inherited traits, , such as the tendency to dislike cilantro because it tastes soapy. Research has shown it’s related to a genetic mutation that affects smell receptors. Science has also discovered links between certain genes and preferences for white wine, bacon, and chicory. There’s even a genetic basis for how our taste receptors interpret bitter flavors.

“Depending on the type of bitter receptors you have, you may be more inclined to accept more bitterness in your food,” says Pepino. “But if you’re more sensitive to bitterness… you will find more bitterness in some vegetables.”

Our bodies might also make us averse to certain foods at specific points in our lives.

When pregnant, women can have very specific food aversions they’ve never had before. These may be heightened because hormonal changes make the body especially suspicious of potentially harmful foods to protect the fetus from toxins.

“These aversions evolved as a second line of defense in order to help protect females during pregnancy, so they don’t ingest toxins and pathogens,” says Caitlyn Placek, biological anthropologist at Ball State University in Indiana. For this reason, animal products tend to be a common aversion, adds Placek, and spicy foods, both of which carry a risk of pathogens and toxins.

But pregnant women around the world aren’t all disgusted by the same foods, so cultural factors like food taboos also affect these aversions. “There might be a biological mechanism that creates the response, the aversion, but the environment is what shapes what the aversion is towards,” says Placek.

Children are also often pickier as a protective measure. They may have similarly evolved this trait to protect themselves at a vulnerable point in life. 

Acquired tastes: the foods we learn to love

It’s possible to learn to like the taste of something, scientists say—you can train yourself out of a food aversion.

Conditioning yourself to like a certain food works best when pairing the flavor with a positive outcome, and repeating this until it becomes more familiar. 

If you want to learn to like something, it’s best to eat that food when you’re very hungry, says Pepino. This way, your brain learns to pair the flavor with the reward of refueling, and the feeling of being satisfied. 

Repeated exposure is important too, adds Mennella. Under the age of two, eight to 10 exposures to a disliked food lowers a child’s aversion, but older children and adults need more exposures to a food to form positive associations.

“Repeated exposure is a powerful one,” says Mennella. You need “the taste of a food in a positive context, every day, for several days.”

Wang’s work focuses on encouraging people to overcome mental barriers against plant-based diets, which requires people to think more creatively about meals and to overcome aversions towards new foods. 

Using the science of flavor in her work to create positive associations with plant-based foods is key to changing minds and encouraging healthier choices. “To promote this transition to different diets, people have to become more creative in coming up with flavor pairings and dishes,” says Wang. “If you are what you eat, then would you be more creative if you eat more creatively?”