TASTE BUDDIES: Science of Sour

Sour taste remains an evolutionary enigma, functioning as a ubiquitous yet poorly understood sense that lacks a clear survival mandate compared to sweet or umami. While humans perceive sourness through acid-sensitive cells in the mouth—often triggering a salivary response to buffer acidity—the biological origins likely trace back to aquatic ancestors. Fish possess chemical receptors across their entire bodies, including their fins, allowing them to navigate acidic environments and regulate physiological functions. This ancestral mechanism may have been repurposed as vertebrates transitioned to land. Science writer Katie Wu highlights that while some species have lost the ability to taste specific flavors, such as carnivores losing sweetness or pandas losing umami, the persistence of sourness suggests it may have historically helped organisms maintain essential nutrient intake, such as vitamin C, despite its current role as a complex, often polarizing sensory experience.