I want to suggest the most likely origin for this vigorous instinct:
We are all a product that is to say survivors of a brood of offspring, each struggling to get its portion of worms or meat or mother’s teat to nourish our ourselves. The offspring that had a very strong instinct to make sure it got enough to eat are the ones most likely to survive.
This is why so many species have this remarkable instinct down to the milligram of whether or not they’re getting as much as somebody else.
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