You can look at Maslow's hierarchy of needs, they need to have their biological and physiological needs, well, as well as being able to provide shelter, food, water and safety for them and others. Lastly they need to be fertile and need to be able to produce and carry offspring. The evolution of the Homo sapiens started when they were able to communicate and survive together as a unit...later they discovered fire and farming to be able to settle down and me safe as a community.