Species that evolved: Australopithecus afarensis, Australopithecus africanus, Paranthropus aethiopicus, Paranthropus boisei, Homo habilis, Paranthropus robustus, Homo ergaster, Homo erectus, Homo heidelbergensis, Homo neanderthalensis, Homo sapiens.
As conditions change, humans become more and more carnivorous. The problem is that the animals they hunt seldom eat plants, so overall there is less food. This competition has extinct certain species.
Natural disasters can lead to human extinction, such as the Hobbit being erased by a volcanic eruption.
Because the living environment changes, people who can't innovate (such as new hunting methods) and adapt to the environment will be eliminated.
Only humans who learn to communicate and share information can survive. For example, this is how language is spread.
Only those who learn to unite can have stronger strength and survive, and those who learn to unite and cooperate will perish.