[5] From February to June 1953, Singh worked as a research assistant for Oscar Lewis who was doing a field study in Rampur, a Jat-populated village, at Delhi in India with financial grant from the Ford Foundation's behavioral sciences division.

[8]: 181–182 Milton Singer stated that Singh, along with Kathleen Gough and Surajit Sinha, was an academic who dealt with "cultural processes which are either recurrent or at least have strong parallels beyond the horizons of a particular time and space".

[9]: 99 Singh's and Mohinder Kumar Bhasin's coauthored book Anthropometry (1968) was assessed by Edward Eyre Hunt Jr.

He suggested that "by and large" their work was "good" but expressed concerns over its "relevance to present-day research and training" in biological anthropology.

[10] University of Oxford's Philip Stewart in 1991, while reviewing Singh's contributions to the first issue of commencing volume of the Journal of Human Ecology, noted that while at that time there was lack of "synthesis" between the two greatly varying approaches towards the study of human ecology – "biological adaptations" and "cultural adaptations" – Singh had worked on both of them.