Singh was born in 1938 in Urai, India. Having first taken degrees in philosophy and psychology (Agra University), he completed his PhD at Ohio State University in 1966. Singh took up teaching positions at Wright State University and North Dakota State University before moving to the University of Texas at Austin in 1969.
A pioneer in the field of evolutionary psychology, Singh's most notable research concerned the evolutionary significance of waist-to-hip ratio (WHR). In 1993, he was the first to elucidate the concept and significance of this ratio as an indicator of attractiveness. In brief, Singh discovered that men rated women with low WHR (0.7) as optimally attractive, noting that lower levels of WHR correlated to lower risk of disease and greater fertility. Subsequent research demonstrated the cross-cultural  and cross-temporal appeal of a low WHR. One of his final research papers on the topic of WHR found that the "hourglass figure" (optimal WHR) activates brain centers that drive appetitive sociality/attention toward females that represent the highest-quality reproductive partners.
- Singh, Devendra (1 August 1993). "Adaptive significance of female physical attractiveness: Role of waist-to-hip ratio". Journal of Personality and Social Psychology. 65 (2): 293–307. CiteSeerX 10.1.1.492.9539. doi:10.1037/0022-3518.104.22.1683. PMID 8366421.
- Singh, Devendra (2011-02-06). "Body shape and women's attractiveness". Human Nature. 4 (3): 297–321. doi:10.1007/BF02692203. PMID 24214368.
- "Looking for something? - Taylor & Francis Online". www.informaworld.com.
- "Elsevier". Radiologysource.org. Retrieved 2011-02-25.
- Singh, Devendra (1993-10-08). "Body fat distribution and perception of desirable female body shape by young black men and women - Singh - 2006 - International Journal of Eating Disorders - Wiley Online Library". International Journal of Eating Disorders. 16 (3): 289–294. doi:10.1002/1098-108X(199411)16:3<289::AID-EAT2260160310>3.0.CO;2-9.
- Devendra Singh1*, Peter Renn2 and Adrian Singh1 (2007-03-22). "Did the perils of abdominal obesity affect depiction of feminine beauty in the sixteenth to eighteenth century British literature? Exploring the health and beauty link — Proceedings B". Proceedings of the Royal Society B: Biological Sciences. 274 (1611): 891–894. doi:10.1098/rspb.2006.0239. PMC 2093974. PMID 17251110. Retrieved 2011-02-25.
- Platek, Steven M.; Singh, Devendra (2010). "Optimal Waist-to-Hip Ratios in Women Activate Neural Reward Centers in Men". PLOS ONE. 5 (2): e9042. doi:10.1371/journal.pone.0009042. PMC 2816713. PMID 20140088.
- Devendra Singh's University of Texas webpage "Devendra Singh, Ph.D". Psy.utexas.edu. 2010-07-08. Retrieved 2011-02-25.