You might like Minsky’s “The Emotion Machine.” Emotion is, as you say, essentially a higher order function of the nervous system—-some complex way of amplifying and dampening certain systems in order to adapt to circumstances. We understand emotion less clearly than we understand multilayer perceptrons/neural networks/basic learning and reasoning.

But even dogs seem to have emotions, don’t they? My dog gets excited if I offer him a treat, and sad if I don’t give it to him.