John Hurrell Crook (27 November 1930 – 15 July 2011) was a British ethologist who filled a pivotal role in British primatology. As Reader in Ethology (animal behaviour) in the Psychology Department of University of Bristol, he led a research group studying social and reproductive behaviour in birds and primates throughout the 1970s–80s, turning to the socio-psychological anthropology of Himalayan peoples in the 1990s. In his later years he was the Teacher of the Western Chan Fellowship. Early life He was educated at Oakmount School, Southampton and Sherborne School, Dorset. He completed his national service in Hong Kong, where he first encountered Chan Buddhism. Academic career Crook was a pioneer in the early development of socio-ecology, adding this dimension to ethology which was then dominated by the ideas of "Niko" Tinbergen and Konrad Lorenz. His student paper on the gulls of Southampton Water while at University of Southampton, led to his doctoral study at Jesus College, Cambridge of the weaver birds (Ploceidae) of West Africa, supervised by William Homan Thorpe and Robert Hinde. This was followed by further research in India, the Seychelles Islands and East Africa. His theoretical interpretation subsequently contributed to David Lack’s discussion of the behavioural component in avian population research. His fieldwork was further supported by laboratory experimentation on the endocrinal basis for the behaviour observed in the field. After moving to Bristol University, he collaborated with Professor K.R.L. Hall in establishing a centre for primate studies, extending socio-ecological principles to primates, supervising doctoral projects and leading field research in Ethiopia on geladas and in Morocco on the Barbary macaque, subsequently developed by Robin Dunbar and John Deag respectively. His year as Fellow at the Center for Advanced Study in the Behavioral Sciences at Stanford University in California introduced him to the new techniques of humanistic psychotherapy. On return to Bristol, his students requested him to demonstrate these methods, leading to the creation of the Bristol Encounter Centre and to his teaching of the subject widely in the UK, especially based on workshops run at his retreat centre in mid Wales. In 1977 Crook led an expedition to Zanskar in the Himalayas of Ladakh, a pilot study focussing on polyandry. For several years, he and colleagues led further expeditions studying the geology, agriculture, social and family life and monastic practices in this remote, high-altitude region. He later returned with James Low, a Tibetologist fluent in the