A humanoid (/ˈhjuːmənɔɪd/; from English human and -oid "resembling") is something that has an appearance resembling a human being without actually being one. The earliest recorded use of the term, in 1870, referred to indigenous peoples in areas colonized by Europeans. By the 20th century, the term came to describe fossils which were morphologically similar, but not identical, to those of the human skeleton. Although this usage was common in the sciences for much of the 20th century, it is now considered rare. More generally, the term can refer to anything with distinctly human characteristics or adaptations, such as possessing opposable anterior forelimb-appendages (i.e. thumbs), visible spectrum-binocular vision (i.e. having two eyes), or biomechanic plantigrade-bipedalism (i.e. the ability to walk on heels and metatarsals in an upright position). Science fiction media frequently present sentient extraterrestrial lifeforms as humanoid as a byproduct of convergent evolution theory.