a specific childrearing niche. Alternatively, Bowlby's thinking about the nature and function of the caregiver-child relationship influenced ethological research, and inspired students of animal behaviour such as Tinbergen, Hinde, and Harry Harlow. One of Harlow's students, Stephen Suomi, wrote about the contributions Bowlby's made to ethology, including that Harlow brought attachment research into animal research specifically with rhesus monkeys and various other species of monkeys and apes. Another contribution according to Suomi was that Bowlby influenced animal researchers to examine separation in animals. Furthermore, Suomi wrote that Bowlby brought to the field of ethology the acknowledgement of the consequences over time from different attachment styles that are prevalent in rhesus monkeys (specifically in the work of Harlow). According to Suomi, "Although Bowlby was a psychoanalyst by formal training, he was a true ethologist at heart". Van der Horst, Van der Veer, and Van IJzendoorn write:Bowlby spurred Hinde to start his ground breaking work on attachment and separation in primates (monkeys and humans), and in general emphasized the importance of evolutionary thinking about human development that foreshadowed the new interdisciplinary approach of evolutionary psychology. Obviously, the encounter of ethology and attachment theory led to a genuine cross-fertilization. "Attachment and Loss" trilogy Before the publication of the trilogy in 1969, 1972 and 1980, the main tenets of attachment theory, building on concepts from ethology and developmental psychology, were presented to the British Psychoanalytical Society in London in three now classic papers: "The Nature of the Child's Tie to His Mother" (1958), "Separation Anxiety" (1959), and "Grief and Mourning in Infancy and Early Childhood" (1960). Bowlby rejected psychoanalytic explanations for attachment, and in return, psychoanalysts rejected his theory. At about the same time, Bowlby's former colleague Mary Ainsworth was completing extensive observational studies on the nature of infant attachments in Uganda with Bowlby's ethological theories in mind. Her results in this and other studies contributed greatly to the subsequent evidence base of attachment theory as presented in 1969 in Attachment, the first volume of the Attachment and Loss trilogy. The second and third volumes, Separation: Anxiety and Anger and Loss: Sadness and Depression, followed in 1972 and 1980 respectively. Attachment was revised in 1982 to incorporate recent research. According to attachment theory, attachment in infants is primarily a process of proximity seeking to an identified attachment figure in situations of perceived distress or alarm for the purpose of survival. Infants become attached to