As a philosophical concept, struggle is emotionally charged and unendingly complex. As a biological phenomenon, struggle is the result of the most basic mechanisms of life. Beneath the surface of every living thing are cells: microscopic factories with furnaces that burn through energy reserves, demolition crews that tear molecules apart, and manufacturing lines where new molecules are fabricated from these pieces. Each time an organism encounters a challenge, its cells respond, firing up the furnaces to build the resources the organism needs to defend, attack, digest, heal, communicate with allies, and show off for potential mates. Those resources accumulate, weaving together an edible record of that organism’s life . . . and death, for that matter. The resulting scrapbook of molecules—ranging in size from bulky structure-builders to tiny messengers—creates what we eventually taste, smell, feel, and see on the plate. Over hours, days, and even years, life seasons our food with the flavor of struggle.