Since Darwin's time, comparative psychologists have searched for a good way to compare cognition in humans and nonhuman primates. In Origins of Intelligence, Sue Parker and Michael McKinney offer such a framework and make a strong case for using human development theory (both Piagetian and neo-Piagetian) to study the evolution of intelligence across primate species. Their approach is comprehensive, covering a broad range of social, symbolic, physical, and logical domains, which fall under the all-encompassing and much-debated term intelligence.