The terms antipodes and antichthones, along with others such as antoikoi and perioikoi, referred to hypothetical peoples dwelling beyond the extent of the known world. These terms were the product of a mathematically based astronomy in which the spherical nature of the Earth was a fundamental element. Calculations of the size of the Earth resulted in the conjecture that inhabited land existed beyond the known world of Asia, Europe, and Africa/Libya. Such land was usually thought to be inaccessible owing to the expanse of Ocean, or because of the extremes of heat and cold found, respectively, at the Equator and the poles.The concept of the antipodes appears to have emerged from Pythagorean thought. Pythagoras was credited with the doctrine that inhabitation was not restricted to the known world, and specifically that there were inhabitants on the opposite side of the Earth, whose “down” was “up” for those in the known world; certain Pythagoreans conceived of an antichthon, or counter-Earth, in relation to the known world (Diog. Laert., Vitae Philosophorum 8.
Natural environments such as the air currents, temperatures, waters, and topography were thought to shape humans, animals, and plants. For humans, the impact was physical, behavioural, and cultural. For animals, the impacts were mostly physical (e.g., oxen in Scythia have no horns because of the cold). This is typically referred to as environmental or climatic determinism. Early explicit examples of this idea include the HippocraticAirs, Waters, Places and occasional comments in Herodotus, but arguments for such a relationship between identity and environment as early as Homer’s Odyssey and Hesiod have been made.1 There is a long-standing tradition beginning with Homer and extending through the Roman imperial period of humans, animals, and their hybrids being associated with geographic distance from an imagined centre, dwelling in designated climate bands, or being earth-born or autochthonous (gēgenēs, autochthōn) that may reflect early forms of environmental determinism. The ideas continue to circulate in much the same form as found in the Hippocratic Airs in Roman authors such as Vitruvius, Manilius, Pliny the Elder, and Vegetius.