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There are quite a lot of diversity in behaviors of animals and lesser organisms, like mating, hunting, feeding, hiding and avoiding predators.

At the same time I know that many hormones like melatonin are present in a variety of organisms.

This makes me interested if animal behaviors did all arise and specialized independently, or did all behavior arise from some primitive response that some "common ancestor" possessed ?

For example, a primitive organism has no concept of predators and can only feed and procreate. Slowly, a predator appears in the ecosystem. Over time, how would the "escape predator" behavior appear in such organism? Would the mating behavior be modified for defense?

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closed as too broad by Devashish Das, Chris, Bez, WYSIWYG, The Last Word Aug 6 at 5:09

There are either too many possible answers, or good answers would be too long for this format. Please add details to narrow the answer set or to isolate an issue that can be answered in a few paragraphs.If this question can be reworded to fit the rules in the help center, please edit the question.

It's little bit too broad. –  Devashish Das Aug 5 at 19:02