Humans are a spacefaring species of hominids. Humans have a strong physical constitution and a highly evolved cephalized centrum (although many changes have improved it) which endows humans with high levels of abstract reasoning, language, problem solving, and culture through social learning. Between the decades of 2040 and 2130 nations states of Earth (and later with the UN's Colonial Authority guidance) conducted massive colonization of the Solar System culminating with the terraformation of Mars in 2135. The databases says that there are 15.28 billion living human beings in 2170.