Australopithecus has a hunch and a small brain compared to modern day humans.
Homo erectus are more advanced (bigger brains) compared to Australopithecus and walks upright.
Neandertal peoples think of reflective thought
Homo sapiens are more advanced (brain size) and have a conscience.
Agriculture lead to an increase of population and the ability to stay in one area without hunting for food so cities formed.