Until the late eighteenth century, a set of arguments provided
seemingly valid etiologies for human diversity: they were based on classical
antiquity theoories on the influence of climate on the physiology of humans
and on accounts of the Bible and its chronology (Cain’s secession from his
family, Noah and the Flood, the confusion of languages at the tower of Babel).
The experience of travellers and missionaries started, from late sixteenth and
early seventeenth century onward, to cast doubts on similar assumptions, and
natural history systematically developed during the eighteenth century a quite
different approach. By comparing the distribution and adaptation of animals to
the climate zones of the globe, it became evident that probably only ‘mankind’
was capable of sustaining itselves under all life conditions, from the torrid zones
to the polar regions. The “geographical history of mankind”, closely linked to
questions of the natural history of the Earth, prompted scientists to substitute
assumptions about congenital diversities of humans by looking at them simply
as varieties of only a single and identical species. Attention will focus on authors
like Aristotle or Hippocrates, who gave rise to the arguments in favour of human
diversity, and on their followers till late eighteenth century; and we will outline
how these views were deconstructed by new ways of conceiving the relationship
between humans and their habitat, by a new chronology of the Earth and by a
more exact knowledge of human physiology. In a set of famous lectures, given in
Berlin in 1827/28, and in the first volume of his masterpiece Kosmos (1845), the
famous naturalist Alexander von Humboldt summed up the results of the debate,
by denying the validity of any concept of different races and defending the unity
of humankind in its variegated forms. The term “diversity” will be used in the following essay regarding theories that admit fundamental differences among
humans, allegedly founded in nature; “variety” will designate the belief in the
existence of one single human species, notwithstanding its various appearances
in body, habits and culture.
