Joseph LeDoux, The Emotional Brain . 1996.
Different emotions serve different functions.
The emotional system we use against danger is different from the one we use in procreation. They have different evolutionary origins and draw on different parts of the brain. To understand human emotions involves understanding our similarities with animals as well as understanding our differences. If an animal has the capacity of self-awareness, it can have some of the same conscious emotional feelings that we have. But we don't need conscious feelings to explain emotional behavior.