Evolution does not need emotions. It is not need love, missing, hurting. It is about a species surviving, going on, adapting, survival of the fittest and emotions would be considered a weakness in survival.
Love - what binds us to our children and our friends and our partners. Take the child bond. Having invested time, energy, food, and attention on an offspring, what binds us to caring for its survival? Why are friends valuable in a survival sense? etc.
Fear - what makes us recognise danger?
Happiness and pleasure - what tells us that our actions are going in a direction that is positive for survival?
Notably, these emotion precede logical thinking in evolution, they are the original signals that evolved to guide our behavior. So they are very much part of our survival kit, and the Spocklike approach of non-emotional analysis of every situation would leave you dead, fast, in a real emergency. Thats why Kirk was the Captain, dummy!