The central theme of this first volume is the evolution of cranial capacity. This is not the first book or article to describe how the size of the female pelvis influences cranial capacity through avoidance of cephalopelvic disproportion during birth. It is the first book to show that brain size is influenced by pelvic size and shape which is related to the dominant mode of locomotion determined by life style. Hunting may be conducted bipedally or brachially in a canoe. Communities may be nomadic or sedentary. This life style writes its story in Man's bones. Now is the time to reconsider prehistoric life styles and the evolution of intelligence. The author attempts to give as much data as is available on the subject as a basis upon which to develop new theory. The ideas which have resulted from this quest could well become areas for new research and investigation.