"Dr. Hal, is love an emotion that only humans have or do other species have it also?"
Answer:
Governor Rocknar, a practicing SubGenius, submitted this one for Valentine's Day. Well, Gov., only humans have human love. But other species feel love in their own way. In the words of the traditional song,
O don't you hear that lonesome dove
That flies from vine to vine?
He's mourning for his own True Love
Just like I mourn for mine."
It is now believed, incidentally, that the cerebrum of a bird is like that of a mammal. Complex behavior, like tool use, vocalization or devoted, monogamous love, seen in the Greylag goose and other Avian species, arises from the interaction between the higher and lower regions of this brain, not in the same way, but to the same effect, as it does in ours. The pejorative, "birdbrain," is just another example of human-centric prejudice. I never use it.