RACHEL MARTIN, HOST:
Imagine your favorite meal. Mine happens to be homemade mac and cheese which I just had the other night. Now try to think about what makes it so delicious. The tang of the sharp cheddar, the punch from that little sprinkle of pepper, the way each warm bite sort of melts in your mouth in this beautiful medley of salty, cheesy goodness. OK. But why do those things make something delicious? And why is what is delicious to me different from what is delicious to you? Why do we taste at all, for that matter? Those are among the questions John McQuaid sets out to answer in his new book. It is called "Tasty: The Art And Science Of What We Eat." And the first thing you need to know - taste and flavor are not the same thing.
JOHN MCQUAID: Taste is a sense sensed by the tongue of certain basic chemicals that are sweet, salty, sour, bitter and umami which is a savory taste. Flavor, which I would say is more of what people experience when they eat, combines taste with the sense of smell because when you chew, aromas are liberated from the food which waft up into your nose. And the brain then combines the sensations, along with other things such as your memories and feelings and the way things look, into the experience of flavor.
MARTIN: You write in the book that - and I'm quoting here - flavor is the most important ingredient at the core of what we are. It created us. That's a big statement. What does that mean? Why do we need flavor?
MCQUAID: Flavor is at the crux of various evolutionary advances throughout the history of life going back more than a billion years because what we consider flavor are the earliest antecedents of it. Among creatures floating around in some ancient sea was the need to sense what was going on around them and to chase it down and to devour it. And so this is kind of a basic motivational hinge that drove evolution because in order to outcompete your fellow primitive creatures, you needed sharper senses. If you had sharper senses, you also needed a bigger brain in order to process those senses. And this also shows up in human evolution. And so humans, as they began eating meat and then cooked meat, their brains grew bigger. Their faces flattened. Their perceptions changed and expanded. And their appreciation of food grew along with the improving taste of the food.
MARTIN: What did you learn about how our preferences play into all of this? Why is it that some of us are really attracted to bitter foods? Others of us have a real sweet tooth and crave sweet foods. Why is that? Is there an evolutionary reason?
MCQUAID: For some of it there is. I mean, sweetness, for example, is very ancient from an evolutionary standpoint because sugars are part of the basic cycle of life. So this is sort of programmed into us from - at a very deep level.
MARTIN: Sugar is life is what you're saying, John.
MCQUAID: Basically. Sorry to say that, yeah.
MARTIN: I knew it.
MCQUAID: However, humanity is weird with flavor in ways that no other creatures are.
MARTIN: What do you mean?
MCQUAID: Because we have certain genetic programming such as liking sugar and disliking bitterness, but we're also very malleable. Our tastes are malleable. This is also partly a result of our evolutionary heritage and that our ancestors lived in so many different parts of the world with so many different types of food and still do that flexibility is programmed into our makeup as well.
MARTIN: So does that mean we can learn to like things?
MCQUAID: That's exactly what happens. We learn to like things that by rights no one should like.
MARTIN: For example?
MCQUAID: Well, I paid a visit to Iceland during my research, and I tried some hakarl which is a type of fermented sea shark. It used to be buried in the sand for months, and then they would dig it up in a semi-fermented, rotted state, and eat it. Vikings did that, I guess, when they had no other option. But today it's a delicacy. It's a national tradition in Iceland. But it smells like a combination of ammonia and rotting fish.
MARTIN: (Laughter) Delicious.
MCQUAID: Yeah. You're supposed to drink it with some Icelandic schnapps and toast the god Thor. I tried this, and, you know, I have to say I did not learn to like it.
MARTIN: (Laughter). Maybe you didn't have enough of the schnapps.
MCQUAID: Perhaps not, yeah.
MARTIN: Maybe that's what's supposed to help.
MCQUAID: But if you live in Iceland, you will learn to like it because you derive other pleasures from it. You derive fellowship, and it's fun. And your brain kind of shifts around. And so things that other people find disgusting, you find enjoyable.
MARTIN: Has this changed the way you eat and taste things?
MCQUAID: Oh, yes, very definitely. I consider each bite much more carefully now and wonder where did this come from, or how is it made? You know, particularly with wines or cheeses which have all these very complex chemicals which set off neurons firing in your memory for associations.
MARTIN: A lot going on when you sit down at the dinner table.
MCQUAID: Yes. Yeah, always. So...
MARTIN: John McQuaid - his new book is called "Tasty: The Art And Science Of What We Eat." He joined us in our studios here in Washington. John, thanks so much.
MCQUAID: Thank you.