How Love Evolved from Sex and Gave Birth to Intelligence and Human Nature

This article argues that emotional attachment drive has shaped the evolution of human intelligence, interpersonal relationships and culture. The first section is about the evolution of social bonds and their role in the rise of intelligence. At the outset, I present evidence that desire for emotional closeness to others is a primary human instinct. Recent discoveries in neurobiology are then incorporated into a summary of the evolution of brain systems that activate emotional attachments and the vital role of parental nurture in the development of offspring's social behavior and capacity to cope with stress. The evolution of maternal behavior is discussed as a particularly important event enabling expansion of brain size and complexity and initiating a pattern of mutually enhancing co-evolution between social complexity and intelligence leading ultimately to the modern human brain. The second section examines how emotional attachment drive may have contributed to the evolution of prominent aspects of human nature and culture. It is hypothesized that the evolution of unique human mental abilities provided vast new outlets for and means of expressing emotional attachment leading to much closer and more diverse interpersonal relationships and the rise and transmission of culture. These developments were very likely important for increasing the adaptive advantages and decreasing the dangers of high intelligence. Emotional bonding between human sex partners was probably selected for because the slow maturation, complex cognitive and psychological development and culture acquisition needs of children required more parental attention for much longer periods compared to offspring of other primate species. Integration of attachment motivation and high intelligence is hypothesized to have been important in the selection of hominid species that were the immediate ancestors of modern humans.