Скорее они не видели такой натуры, но ХОТЕЛИ чтобы так было, утрируя до предела.
Что называется чем больше мамонта нарисуешь, тем крупнее завалишь...
И при этом точно совпали с конкретной формой ожирения?
Это все равно, что ни разу не видя карлика, сделать статуэтку очень малорослого человека, и при этом получить случайное совпадение именно с пропорциями карлика. Исключено.
А натуры им вполне могло хватать.
Ср.
The Soul of Central Africa. General Account of
The Mackie Ethnological Expedition. By the Rev. John Roscoe,
Hon. M.A. (Camb.), Leader of the Expedition
Cassell and Company, Limited, London
New York, Toronto and Melbourne 1922
Речь идет о некоторых племенах Уганды.
Women have little work to do, their duties being
confined to washing and fumigating milk-pots and churn-
ing butter. There is no cooking, except on the rare
occasions when a cow is killed or dies. No matter what
the cause of a cow's death may have been, the meat is
always eaten. Then a wife may undertake to cook some
of the meat for her husband, but even this is generally
delegated to one of the male servants, lest the extra work
should be wearisome to her and, by sympathetic magic,
injurious to the herd. The result of this indolent life,
together with the quantities of milk which they drink,
is the abnormal fatness to which I have referred. This
obesity is looked on by all classes as a mark of beauty.
Girls, before marriage, are not allowed to walk about,
and are encouraged to drink as much milk as they can,
in order that they may become as fat as possible before
their affianced husbands come to claim them. After
marriage women practically lose the power of walking ;
half a mile will take them two or three hours to accom-
plish, for a rest is necessary after every few yards. In
their dances these fat women remain seated and go
through a performance which consists in waving their
hands and arms gracefully and swaying their bodies to
and fro, making meanwhile a buzzing sound with their
lips, to the rhythm of which the men caper and jump
about, full of admiration for the women who are too fat
to stand.
Вообще, см. на эту тему о хима и анколе.