At the University of Birmingham [1955- 58] under a grant from the Wenner-Gren foundation for anthropological research, New York, he designed the “Pelvimeter”, for the measurement of angles of torsion on the pelvis and other bones of primates including man, which had been impossible to achieve at the time with the conventional osteometry instruments. The design of the instrument and its applicability were published in 1958 in the Journal MAN, published by the Royal Anthropological Institute, London. His professional academic journey started in the year 1957. From 1957 to 1958, he served as an invited lecturer at the Duckworth Laboratory, University of Cambridge, U.K.
In 1959, he returned to India. He joined as a Reader in Anthropology in the Department of Zoology at Panjab University on 2nd April 1959. Within a year, he successfully separated from the Zoology department to establish an independent Department of Anthropology. In 1960 he married Krishna Taneja, his lifelong companion and a woman of great strength and resolve who stood by him through thick and thin. Same year, he became one of the youngest Founder Heads of an integrated Department of Anthropology in independent India. His academic and administrative genius started flourishing at the young age of 30. By this time, he was recognised as one of the leading paleoanthropologists in the World. He served as Chair of the department till 1981, a tenure of more than twenty years through which he positioned this young department as a pioneer in research in various domains of biological and social-cultural anthropology. Under his expert guidance, the department emerged as a centre of excellence for paleoanthropological studies.
From 1967 onwards, he, along with his team, investigated various hominoid and other fossils from the Sivalik region. To his credit, stands the discovery of a new fossil Gibbonoid tooth from the Sivalik Hills. His work, including the discovery of fossils like Gigantopithecus Bilaspurensis, Pliopithecus Krishnaii (in the Miocene beds) and Sivasimia attracted widespread attention. This was followed by several collaborative projects funded by different national and international institutions. Some of the findings from various collaborative projects were presented at the second international Congress of Primatology held in Atlanta, Georgia, USA in 1968 and were subsequently published in Recent Advances in Primatology.
Professor Chopra made cardinal contributions not only to his primary interest in strengthening palaeoanthropology but also to the holistic approach and integrated character of the discipline. Research articles published in Nature and Human Biology symbolize that spirit. He identified and brought talent from different parts of the country to teach in this new department and encouraged them to take up challenging tasks and projects. He supervised 19 PhDs and was an examiner at both international and national universities with a fluency in both English and German languages. Students trained in the department were hired with ease by various national and international universities as also in allied institutions like anthropological and archaeological Survey of India because of the training they received under his supervision. The Department of Anthropology, Panjab University was one of the first departments in the country to introduce a diploma in Forensic Science/ anthropology under his visionary leadership. Ethnographic explorations in remote areas of Himachal Pradesh, Kinnaur and Lahaul Spiti was also initiated under his guidance.
He went on several international assignments to various Universities across the world. Few of the most prestigious teaching assignments were at the universities across the United Kingdom, West Germany and Japan. From 1965 to 1967, he was a Visiting Professor in the Institute of Anthropology at the University of Kiel in West Germany. Continuing to take his wealth of academic experience abroad, in 1979 he was invited to the Primate Research Institute at Kyoto University in Inuyama, Japan, as a Visiting Professor. Among his many Awards, reference must be made of the Wenner-Gren Foundation Award for Excellence twice from 1955 to 1956, and then again in 1966 to 67. He was fellow of the Royal Anthropological Institute of Great Britain and Ireland as also fellow of the Zoological Society of London and Member, Permanent Council, International Association of Human Biologists along with several reputed national organizations. He also Chaired the session on Paleo-Biology and Evolution for the 7th Congress of International Primatological Society in 1979.
He received a silver plaque from the Ethnographic and Folk Culture Society, Lucknow in 1976 and also delivered the Majumdar Memorial Lecture there. From 1980-81, he served as the UGC national Lecturer. Some of the other prestigious lectures that he delivered in his career include the 1984 M.R. Sahni Memorial lecture to the Paleontological Society of India and the 1985-86 Dr. Panchanan Memorial Lectureship, Asiatic Society, Kolkata. He also served as the Editor of Everyday Science and as Member of the Advisory Committee of Anthropological Survey of India, and the Indira Gandhi National Museum of Man, Ministry of Culture. Additionally, he held the esteemed position of the President of the Indian Association of Physical Anthropology from 1976 to 1978. In 1989, he was bestowed the Excellence Award by the Shiromani Nehru Centenary Committee for enhancing India’s prestige and contribution towards National Development.