Can Insects be Happy?

Like most sensible folk, I occasionally spend my afternoons wondering whether life forms other than my own can experience feelings of happiness.  After all, I have only to look out my window to notice that four or five dogs are currently playing in the yards neighboring mine.  And those dogs appear to be happy.

Beyond the simple appearance of happiness, it would not at all surprise me if those dogs now and then actually felt happy.  That's because dogs and humans are related to each other through evolution and, consequently, we share some of the same neurochemistry.  It's certainly not hard to imagine the possibility that similar -- or even identical -- neurochemical processes occur in both humans and dogs.

Besides, if, as some scientists now suspect, the same neurochemical processes can produced feelings of happiness in both humans and politicians, then how much more likely is it that the same neurochemical processes can produce feelings of happiness in both humans and dogs?

It seems, though, that thinking about happiness in dogs naturally leads one to wonder what is the simplest animal that can feel happy?  Can birds feel happy?  What about frogs and salamanders?  Spiders?  Insects?  Worms?

To me, the cool thing is that it seems we are able -- at least in theory -- to somewhat answer those questions. In theory, we could establish the precise neurological processes that are associated with feelings of happiness in us.  We could then check if those exact processes were ever present in other animals.  And if we discovered that they sometimes were, then we would have a clue suggesting other animals might sometimes feel happiness.

Of course, even then, it would be extremely problematic to assert that many other animals do in fact feel happiness in much the same way we do.  There are simply too many variables for any conclusive answer.

All the same: Some might find it an interesting question if only because answering it might shed some light on human happiness.  And, as for myself, I would love out of simple curiosity to better understand the evolution of feelings of happiness.