The term "Human" (also known as "Colonial") as it was used within the reimagined Battlestar Galactica series typically referred to a member of a sentient mammalian bipedal species originally from the planet Kobol. They were an outwardly indistinguishable from Homo sapiens extraterrestrial race with compatible DNA to Homo sapiens, as a result of a parallel evolution of hominids on both Kobol and Earth. The Colonial humans were a Kobol-evolved Homo sapiens analogue.
There are no longer "pure" Kobol-evolved humans living, meaning that humanity, as it was defined by people in the Twelve Colonies of Kobol, has become extinct. The modern humans of Earth are a product of hybridization between them and the original indigenous native Earth-evolved Homo sapiens.
A notable physiological distinction of Kobol-evolved humans from Earth-evolved humans was the lack of a universal donor blood type—Type O Negative.