Park found that a key underpinning of his human ecology is the concept of competition. He believed that it is the primary feature of the biotic level of life. He maintained that human beings restricted in some areas when it comes to competition, while in the plant and animal kingdom it is uninhibited. He maintained that human restriction of competition is what allows our modern concept of society to exist. According to Park's papers regarding this topic, "Dominance" and "Succession: An Ecological Concept", ecological competition can be manifest itself through dominance and succession.