This is the abstract from a research article describing our innate needs for movement:
The model for human physical activity patterns was established not in gymnasiums, athletic fields, or exercise physiology laboratories, but by natural selection acting over eons of evolutionary experience. This paper examines how evolution has determined the potential for contemporary human performance, and advances the experience of recently-studied hunter-gatherers as the best available (although admittedly imperfect) indicator of the physical activity patterns for which our genetically determined biology was originally selected. From the emergence of the genus Homo, over 2 million years ago (MYA), until the agricultural revolution of roughly 10000 years ago our ancestors were hunter-gatherers, so the adaptive pressures inherent in that environmental niche have exerted defining influence on human genetic makeup. The portion of our genome that determines basic anatomy and physiology has remained relatively unchanged over the past 40 000 years. Thus, the complex interrelationship between energy intake, energy expenditure and specific physical activity requirements for current humans remains very similar to that originally selected for Stone Age men and women who lived by gathering and hunting. Research investigating optimal physical activity for human health and performance can be guided by understanding the evolution of physical activity patterns in our species.
Cordain L, Gotshall RW, Eaton SB, Eaton SB 3rd. Int J Sports Med. 1998 Jul;19(5):328-35. Physical activity, energy expenditure and fitness: an evolutionary perspective. Department of Exercise and Sport Science, Colorado State University, Fort Collins 80323, USA.