Traditionally the comparative study of brains of apes and humans has been of interest to anthropologists, but not to neuroanatomist who are more concerned with the human brain per se. But, very few anthropologists have the background and expertise to deal in detail with problems of the comparative morphology of human and non-human primate brains. Dr. Armstrong is one of these few. This research involves detailed measurements of the gyration and degree of maturation in diencephalic nuclei of the brain of humans, apes, and monkeys. Despite this neuroanatomical detail, the study does have broad relevance for Anthropology. Anthropologists and the general public alike have wondered for a long time whether differences between human, monkey and ape brains are related to differences in intelligence. An understanding of developmental differences between human and nonhuman brains has a direct bearing on this question. This research attempts to answer the specific question, Can merely a shift in the rate of neural development account for differences in size of (parts of) adult human and monkey brains? It makes use of the extensive collection of well-preserved brains in the Yakovlev Collection of Armed Forces Institute of Pathology.