Morality and empathy are the building blocks of civilization. By removing or diluting them the foundations of humanity are compromised which starts a process of dehumanization and ultimately leads to the reversal of the hierarchy of living creatures, where man is no longer at the top.
The reason man is on top is because he has free choice. Lesser creatures do not and are in essence more perfect than man, because they are true to their purpose. A simple example would be a lion. This creature cannot exercise its free choice and become vegetarian.
Man, on the other hand, can choose. If man chooses to do what is moral and good (for everyone and not in self-satisfaction of primal desires at the expense of others) despite being able to do the opposite then he becomes true to his purpose and validates his position at the top of the hierarchy of creation. If however, man forsakes morality and empathy for others then he is reduced to the absolute bottom, below lice and vermin who at least are true to their intended purpose.