Taste, designed in part to help us reject harmful foods, has long served as the body’s primary defense against poison. As befits its role, the system is lightning fast: The body can ­detect taste in as little as .0015 seconds, compared with .0024 seconds for touch and .013 seconds for vision. To be tasted, food molecules must fall into a cluster of cells called a taste bud, more than 10,000 of which are spread over the tongue, palate, and inner cheek. The taste bud sends a signal to the brain, which then determines everything from whether a food tastes “safe”—which in most cases means it’s not too bitter—to whether we enjoy it. In a part of the brain known as the anterior cingulate, tastes get married to an emotional reaction: disgust for rotten meat, say, or delight for a sweet strawberry. But while some tastes are innate—nearly all humans are born with a sweet tooth—there’s also evidence that taste can be nurtured. Studies have shown that babies prefer foods they first “tasted” in the womb, or while nursing. (Traces of certain flavors, including garlic and vanilla, turn up in amniotic fluid, and also in breast milk.) More recently, food scientists have found ways to manipulate our likes and dislikes. One chemical, extracted from a West African fruit, binds to taste receptors in a way that makes even the sourest lemon taste as sweet as lemon pie. Food scientists have jumped on the discovery, scrambling to devise additives that would trick our taste buds into perceiving sweetness in the absence of actual sugar.