A Moment of Science

Where “Yum” Comes From

Our love of sweetness is written directly into our genes. Learn more on this Moment of Science.

Tropical fruit stand

Photo: mralan (flickr)

Fruit most likely explains our craving for sweets, which, over millions of years of evolution, resulted in being written directly into our genes

Do you have a sweet tooth?

Try as you might, you just can’t avoid eating things that stimulate the sense of sweetness: candy, ice cream, soda. You can relate to those ancient kings who believed chocolate to be the food of the gods.

Take comfort, we human beings have inherited our predilection for sweet tastes across millions of years of evolutionary history. Our love of sweetness is written directly into our genes.

Why do we have such a craving, when it leads to unhealthy dietary habits and rotten teeth? Ironically, the answer is probably fruit.

Most fruits exude a form of fructose, or sugar, at a certain phase in their maturation. If the fruit is not yet ripe, it will taste bitter, or if it has gone over the top, sourness rules. The chemical balance that translates to sweetness comes only at the critical peak, and thus at the point where it is a good idea to eat that apple.

Having a natural cue like this ensures we get the most nutrition from the fruit. The apple tree also benefits by having its fruit plucked at the right time, because that increases its chances of spreading mature seeds. Thus the sweetness acts as a trigger to fruit-eaters to grab these now!

The danger, however, is that the love of sweetness has become hard-wired into the human genetic makeup. We won’t eat rotten fruit,  but we also go a little crazy when we taste anything with sugar in it, whether that something happens to be good for us or not.

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