S Brown of Caversham, Dunedin, asks :-
How did the different nationalities of the world come to have different characteristics?
John Dennison, of the Department of Anatomy and Structural Biology at Otago University, responded.
They didn't. We love to compartmentalise. Egyptian tomb paintings showed: black-skinned people with curly hair; creamy-yellow-skinned people with slanting eyes; light-skinned people with blue eyes and blond beards; and reddish-skinned Egyptians. In the 1700s von Linne divided humans into Americanus (red); Europeanus (white); Asiaticus (yellow); and Africanus (black). Cuvier classified humans into white, yellow, and black. Blumenbach, (1775) using skull shape, proposed the 'ideal' - the Caucasoid archetype, (Caucasian from Georgia), evolving via Native American Carib to Mongolian from Tungus, and, in the opposite direction, via Tahitian Malay to Ethiopian African.
We are realising that 'race', with its political, socioeconomic, intellectual and cultural baggage, exists only in our minds - greater diversity exists among individuals than among groups; differences are just in 'degree'. When I first saw the Vienna Boys' Choir, I expected only blond-haired, blue eyed boys - some weren't. I was once checked by a frizzy, red-haired customs officer in Istanbul. Particular skin pigmentation, hair texture, and eye shape must be present in the 'whole' race, but be more dominant to that 'race' alone. This does not happen - not all Swedes are blonde, blue-eyed - look at the old pop-group ABBA. Conversely, blue-eyed blondes do occur in Africa, and in Australia where they are considered gods on an earthly sojourn.
Long legs are good for chasing prey in open country; strong arms for canoe paddling. However, these traits of the 'fittest' are superior only in their particular environment, at a particular time. Natural selection involves better integration into that environment, more efficient use of food, and better care of young - success measured by the number of surviving young.
We humans are all part of one continuum, each with our own imperfections. One may argue that a preponderance of Aisians have the Mongoloid eye fold, but so do Inuits, North and South American Indians, and Kalahari bushmen. Again, not all Africans have black skins. The bottom line is, that traits are not inherited in chunks, but only by single genes.