Welcome to LessWrong, and thanks for posting!

Regarding the evolution of emotions, consider this:

Imagine a group of life forms of the same species who compete for resources. Lets say that either they are fairly even in power level, and thus it is superior for them to cooperate with each other and divide resources fairly to avoid wasting energy fighting. Alternately, some (alphas) are superior in power level, but the game theoretically optimal outcome is for the more dominant to take a larger share of resources, but still allow the others to have some. (This is superior for them to fighting to the death to try to get everything).

If life forms cannot communicate with each other, then they suffer from a prisoner's dilemma problem. They would like to cooperate in the prisoners dilemma, but without the ability to signal to each other, they cannot be sure the other will not defect. Thus they end up defecting against each other.

We can thus see that if the life forms evolved methods of signalling to each other, it would improve their chances of survival. Thus, complex life forms develop ways of signalling to each other. We can see many, many examples of this throughout a broad range of life.

The life forms also need to be able to mentally model each other now to predict each other's actions. Thus they develop empathy (the ability to model each other), and emotions, which are related to signalling. If each of the members of the species have similar emotions, that is , they react in similar ways to a given situation, and they have developed ways of expressing these emotions to each other, then it greatly improves the abilities of the life forms to model each other correctly. For example, if one life form then tries to gain an unfair distribution of resources (defecting in the prisoners dilemma problem), the other will display the emotional response of anger. They are signalling 'you cannot defect against me in such an unfair way. Because you are attempting to do so, I will fight you'.

Because the emotional responses occur automatically, they act similar to a precommitment. Essentially, the life form having the emotional response has been preprogrammed to have this response to the situation. This is a precommitment to a course of action, which can help the life form to achieve a better game-theoretic result.

(For example, if we are playing 'chicken', driving our cars toward each other on a road, the best strategy for me to win the game is to visibly precommit to not swerving no matter what. Thus, the optimal strategy would be to remove my steering wheel and throw it out of the car in a way that you can see. Since you now know that I CANNOT turn, you must turn to avoid crashing, and I win the game. This shows how a strong precommitment can be an advantage).

If we think of emotions as precommitments in this way, we can see that they can give us an advantage in our prisoner's dilemma problem. The opponent then knows that they cannot defect against us too much, or else we will become angry and will fight, even though this gives a worse outcome for us as well, it is an emotional response and thus we will do it automatically.

We can see that emotions are thus an aid to fitness, and life forms that evolve them will have a genetic advantage.

Now imagine that the problems that the life forms need to signal about become much more complex. Rather than just signalling about food or mates, for example, they need to signal about group dynamics, concepts like loyalty to a tribe, their commitment to care for young, etc.

Under these circumstances, we can see the need to develop a much greater range of emotions to deal with various situations. We need to display more than just anger over an unequal distribution, or fear, or so on. We also need to have emotional responses of love, loyalty, and so on, and be able to demonstrate/signal these to each other.

This is my understanding of how emotions should evolve among complex life forms that are at least remotely close to humans. Perhaps for extremely different life forms, emotions would not evolve. Or perhaps in pretty much all complex forms of life which are communicating with each other, some form of emotions would evolve, I don't know. I don't see the need for a magical sky-father to have desired emotions to exist, who then guided reality to this point.

Also, I am not sure how the universe-creator would accomplish this. If the degrees of freedom they have are to create the underlying fundamental laws of physics, and the initial conditions of the universe, how would they be able to compute out what sets of laws/initial conditions would lead to the physics which would lead to the chemistry which would lead to the biology which would lead to the life forms which would have these emotions? And why would that be the goal of the universe-creator? In the absence of evidence which would distinguish this hypothesis from others, I don't see why we should privilege this hypothesis to such an extent, when it is pretty clear that the real reason for "believing" in it is actually "I want it to be true". (And also "A strong meme which many people believe in is threatening that I will be harmed if I do not "believe" that this is true, and promising to reward me if I do "believe" it is true).

If anyone can correct my thoughts regarding evolution and emotions, or can point to some studies or scientific theories which either support or refute this post, I would love to read them!