Humans throw the term "purpose in life" around like it relates anything to a career they may choose. But our species true purpose really comes down to the will to survive and reproduce. The will to survive produces selfish, cunning, manipulative, dominant, and heartless characteristics. The will to reproduce produces loving, protective, sacrificing, and caring characteristics. When you take the instinct to reproduce out of a humans brain you end up with a sociopath/psychopath who's basic characteristics are the ones concerned with the self survival mechanism.
Just throwing some ideas around, any thoughts on this?