Models for the appearance of Homo sapiens

The development ofHomo sapiens on the earth's surface represents the second great expansion of hominins outside Africa after that ofHomo erectus. It was also the most complete, insofar as it led to a drastic reduction in the group's biological diversity. However, even if all current human populations have a recent common origin, they have adapted to very diverse and sometimes extreme environments. Questions have long been raised about the origins of the differences observed between people living in different parts of the world. In the Age of Enlightenment, long before the success of evolutionary theories, debates between monogenists and polygenists were already raging, tinged with philosophical and religious concerns. This can be seen as the source of more recent controversies in^{twentieth-century} Paleoanthropology. From Franz Weidenreich (1873-1948) to Milford Wolpoff, "multi-regional" models long prevailed. They emphasized the genetic inheritance of local, non-modern forms presumed to be ancestral to present-day groups, and thus supported a very ancient diversity of modern humans. However, in the last decades of the century, monocentric models finally gained widespread acceptance. While human paleontology established the greater antiquity of our species and its contemporaneity with forms such as the Neanderthals, more and more detailed genetic data demonstrated its African origin.