One thing I know is that according to the Genesis account in the Bible, when God made man he put him in the garden of Eden and told him to eat from every tree of the garden except one. So at the start meat was not a part of the human diet. However after the flood in the days of Noah, when he and his family and the animals came out of the Ark God told them that every moving animal that is alive may serve as food for them Genesis 9:3-5. So both the vegetation and the animals are good sources of food for humans. No one has the right to bash persons who choose to eat vegs only and no one has the right to bash those who eat meat as well. All have been given as food to us to sustain our bodies from the Creator of the human anatomy. He surely knows more than any human no matter how scientific or knowledgeable they think they are. Balance is what is needed.