Well, if one believes ones is nothing more than the most advanced animal to be evolved so far, this is logical. Humans are not unique or even special!
OTOH, if one truly believes in evolution, whence comes ideas such as murder being wrong or rape being wrong or things humans do in the processes of living are "pollution" or "not natural"? Or even the idea of "rights"?
The materialistic worldview is rife with such self-contradictions.