Okay. Basic disambiguation: do you mean emotions as in complex aggregations, e.g. a thought with valence attached, or down to the level of body sensations like those you get when you're sad?
Because those serve fairly different functions.
Okay. Without "feelings", i.e. somatic sensations and drives, you almost certainly die.
It's all basic survival stuff with basic survival functions. You'll want to read some nonshitty evpsych, but I'm short on recommendations here. I mostly read textbooks in uni, long ago.