This very well proved by numerous archaeological founding theory was published on 1955 by Australian anthropologist Raymond Arthur Dart. (See: «The Predatory Transition from Ape to Man» , (International Anthropological and Linguistic Review, 1:201-208).
Approximately two million years ago there was created certain type of APES — PREDATORS (Generally all apes are vegetarians, although they eat sometimes meat. Very rare.) But as said two million years ago by mutation of genes there came predatory apes that ate meat. Very shortly they “understood” that the best and easier way to get meat is CANNIBALISM!
But in cannibal “society” the natural selection became very sharp, brutal and, at the same time, very effective. Only very canning, brutal, bloodthirsty apes could survive in such conditions and to bring “children” with the same genes of absolute absence of compassion and mercilessness! They ate their parents too! This process only created HUMAN BEINGS! Hundreds discoveries were made confirming this theory. In Germany this process of cannibalism existed till only one thousand years ago!!! In Spain – the same. In Central Africa and Papua-New Guinea TILL NOW that “habit” exists!
Now the question: Where GOODHEARTED people come from?
Answer: Again, mutations. They exist at any time and produce MUTANTS, who can NOT follow those good and two million years proved habits!
So, don’t be surprised looking “human beings” today’s behavior.