I'm not a biology person at all so please forgive me if my question is silly. I was just wondering that why didn't evolution cause us to digest, without issues decomposed food?

  • $\begingroup$ What evolutionary advantage would that give us? "Rotten" by definition means that some or all of the usable nutrients have decomposed, so what is the point? $\endgroup$
    – MattDMo
    Commented Aug 18, 2020 at 16:22
  • $\begingroup$ Well imo animals eat half decomposed things. $\endgroup$
    – Kashmiri
    Commented Aug 18, 2020 at 16:26
  • $\begingroup$ I understand that is what spices were originally used for ; to mask bad flavors in food that is "turning" ( bad). $\endgroup$ Commented Aug 18, 2020 at 16:27
  • 2
    $\begingroup$ There's really no "why" answer here, any more than you can say "why" cows eat grass, or blue whales eat krill. Evolution doesn't have a purpose or goal. The only answer is "because our ancestors survived without eating rotten food". $\endgroup$
    – jamesqf
    Commented Aug 18, 2020 at 16:31
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    $\begingroup$ You could argue that we have the ability to eat certain "rotten" foods, those that have fermented. $\endgroup$
    – Bryan Krause
    Commented Aug 18, 2020 at 16:48

1 Answer 1


Food is considered "rotten" when it has a large population of micororganisms like bacteria and fungus eating it. Some of these microorganisms have evolved to produce toxins that harm animals that would otherwise eat the food. Animals could evolve to tolerate these toxins, and some have. However, bacteria have a large advantage over animals in an evolutionary arms race due to their short generation time and large population number. So competing with bacteria over carrion is a specialized niche, avoiding it has been selected for in most animal lineages.


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