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How does coevolution lead to nontasters of PTC?

Okay so we are doing a lab report an experiment we did in class on the human genetics of taste and this is one thing we need to have in our report.

PTC is a nontoxic chemical that represents a molecule in some poisonous plants and tastes bitter to most people. Tasting this is dominant, and not being able to taste it is recessive.

So if we co-evolved with poisonous plants by developing the ability to taste the bitterness in plants, and them developing the ability to taste bitter, then I can see how this would lead to tasters of PTC. People who could taste it would know that the plant is poisonous and know to spit it out. Having this dominant trait would be beneficial and therefore coevolution would lead to PTC tasters. Which leads to the question again: How does coevolution lead to nontasters of PTC? How would us co-evolving with toxic plants cause more nontasters when it would be better to taste them?

This question has been on my mind all day and I can t figure out the answer. If anyone could help that would be great. Thanks!

1 Answer

  • 3 years ago
    Favorite Answer

    In humans, the non-taster allele is no longer selected against. In humans, most of learning what to eat and what not to eat is culturally learned. We have language and society and things like that, so the pressure on bitter taste alleles is reduced.

    PTC non-tasters do still taste many bitter compounds, just not certain ones.

    Since humans no longer rely primarily on tasting bitter things to decide what to eat and not eat, the random occurrence of PTC non-taster mutants is no longer strongly selected against, and so have become more common in the population.

    • Michael3 years agoReport

      Thank you! That makes sense. I ended up putting that since not all bitter tasting plants are poisonous, coevolution would lead to non-tasters because then the non-tasters could eat the non-poisonous bitter plants and have no bad taste. That's what I was guessing. This makes more sense though lol.

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