Abstract: Weidenreich made a detailed in-depth description of the fossils of Sinanthropus pekinensis ( now Homo erectus pekinensis) and pointed out the characteristic features of Homo erectus. He rightly postulated that the adoption of erect posture was achieved first and the transformation of skull follow ed. Brain enlargement was the motive cause of the change of skull as illustrated by the different sizes of dogs.
Weidenreich was the first man in history in the first half of the present century attempting to correlate all human fossils yet found in the world with a chart. He believed all fossil humans belonging to one species and could interbreed each other. Man did not originate from one place but several places. He rejected the Australopithecine fossils then found in south Africa playing any post in human evolution and instead suggested a giant phase as the first human period.
His giant theory of origin of man so far has no fossil evidence. As to the origin of modern man, the Multiregional hypothesis and the Out of Africa one are now in hot debate.

Key words: F. Weidenreich, Sinanthropus pekinensis, Human origins