The Sweetness of sugar is one of life’s great pleasures. People’s love for sweets is so visceral, food companies lure consumers to their products by adding sugar to almost everything they make.

The attraction to sweetness is so relentless that it has been called an addiction comparable to nicotine dependence, itself notoriously difficult to overcome. I believe it is worse than that. Nicotine is an unwanted outsider to our bodies. People desire it because it plays tricks on the brain.

How deeply sweet perception is embedded in human beings?

Sweet perception begins in taste buds, clusters of cells nestled barely beneath the surface of the tongue. They’re exposed to the inside of the mouth via small openings called taste pores.

Different subtypes of cells within taste buds are each responsive to a particular taste quality: sour, salty, savory, bitter, or sweet. The subtypes produce receptor proteins corresponding to their taste qualities, which sense the chemical makeup of foods as they pass by in the mouth.

One subtype produces bitter receptor proteins, which respond to toxic substances. Another produces savory receptor proteins, which sense amino acids, the building blocks of proteins.

Sweet-detecting cells produce a receptor protein called TAS1R2/3, which detects sugars. When it does, it sends a neural signal to the brain for processing. This message is how you perceive the sweetness in the food you’ve eaten.

Genes encode the instructions for how to make every protein in the body. The sugar-detecting receptor protein TAS1R2/3 is encoded by a pair of genes on chromosome 1 of the human genome, conveniently named TAS1R2 and TAS1R3.

The TAS1R2 and TAS1R3 genes aren’t only found in humans. They’re found in monkeys, cattle, rodents, dogs, bats, lizards, pandas, fish, and a myriad of other animals. The two genes have been in place for hundreds of millions of years of evolution, ready for the first human species to inherit.

The body’s sensory systems detect myriad aspects of the environment, from light to heat to smell, but we aren’t attracted to all of them the way we are to sweetness.

A perfect example is another taste, bitterness. Unlike sweet receptors, which detect desirable substances in foods, bitter receptors detect undesirable ones: toxins. And the brain responds appropriately.

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