Humans are distributed across the globe except for Antarctica and form a variable species. In adults, the average weight varies from around 40 kg (88 pounds) for the smallest and most lightly built tropical people to around 80 kg (176 pounds) for the heavier northern peoples.[2] Size also varies between the sexes, with the sexual dimorphism in humans being more pronounced than that of chimpanzees, but less than the dimorphism found in gorillas.[3] The colouration of skin, hair and eyes also varies considerably, with darker pigmentation dominating in tropical climates and lighter in polar regions.