Much of what you say has much merit but that does not mean unconditional love between humans does not exist. Take your parental love point. Punishing a child to alter their behavior does not make the love conditional. The parent is not conditioning their love on the altering of behavior. Two years ago I asked my mother to define love of a child for me. She said: "The love for my children is unconditional and even though I may not always 'like' what they do it does not affect the emotional love.”