The Evolutionary Origins of the Sweet Tooth

In an interview at The Smithsonian, evolutionary biologist Jason Cryan explained why humans generally have predisposition to sweet foods and a disinterest in bitter foods:

The evolutionary explanation for the sweet tooth revolved around that idea that we have physiologically associated a sweet taste with high-energy foods which would have helped our earliest ancestors survive better in their environment (getting more “bang-for-the-buck”….if an individual has to spend time and effort foraging for food, it’s better to obtain energy-dense food items than energy-poor food items). When one considers our ability to taste, our ability to perceive “sweet” is relatively weak, while our ability to perceive “bitter” is generally considered much stronger (in fact, the strongest of our taste reception, on average). Perception of “bitter” is thought to be an evolutionary strategy of quickly identifying plants that contain potentially harmful toxins (produced as secondary plant compounds). Thus, evolving a low tolerance to “bitter” and a high tolerance to “sweet”‘ might have promoted our ancestors to actively seek out sweet tasting foods.

Cryan also notes that all animals that have been tested favor sweet foods -- except for cats. Cats may have lost the ability to taste sweet foods due to a wholly carnivorous diet.

Link | Photo: US Department of Health and Human Services

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I suspect that many cats are attracted to other aspects of sweet foods, besides the sweetness itself. There are various aromatic chemicals in fruits that may attract them... I think that they "like" cake and pastries because of the fats in them, or I should say, the smell of fats, since cats are initially attracted to foods by smell. Of course, for any species, there is always tons of variability amongst individual organisms, so in biology there exceptions to almost every "rule"...!