Contents lists available at ScienceDirect HOMO - Journal of Comparative Human Biology journal homepage: www.elsevier.com/locate/jchb Molar crenulation trait definition and variation in modern human populations M.A. Pilloud a, ⁎ , C. Maier b , G.R. Scott a , H.J.H. Edgar c a Department of Anthropology, University of Nevada, Reno, USA b Eckerd College, St. Petersburg, FL, USA c University of New Mexico, Albuquerque, USA ARTICLE INFO Keywords: Dental morphology Crenulated molar Forensic anthropology Dental non-metrics Wrinkled enamel ABSTRACT Crenulated molars have been used extensively in biological anthropology. However, the trait has not been formally defined, nor have population frequencies been thoroughly outlined. This study provides a formal definition of molar crenulations and data on their presence in a large sample. Data were collected on maxillary and mandibular molars of modern dental material from various populations: South African, Hispanic, Japanese, American White, and American Black (n = 750). Molar crenulations were defined and a rank-scale created. Statistical analyses include chi- squared, correspondence analysis, and trait correlations. Significant statistical differences were found between populations in all molars. Minimal sexual dimorphism was noted, and is most pronounced among the American Black sample. Generally, American White and Japanese sam- ples showed lower frequencies of molar crenulations, the highest frequencies were seen in the American Black and South African samples, and the Hispanic sample was intermediate. Correspondence analysis showed that American Black samples tended towards grade 2, and South African samples were more often a grade 1. American White and Japanese samples were most often grade 0, and Hispanic samples were intermediate. Correlations were noted across the molars. Population differences exist in the presence of molar crenulations, which were likely shaped by evolution. Based on these results molar crenulations can be added to the suite of traits currently used to study population differences. Introduction The condition of crenulated (or wrinkled) molars has been described extensively among extant primates (e.g., Haile-Selassie, 2001; Vogel et al., 2008; von Koenigswald, 1982), in primate (e.g., Chaimanee et al., 2003; Leakey et al., 1965; Pickford, 1985) and hominin evolution (e.g., Berger et al., 2015; Carbonell, 1965; Martinón-Torres et al., 2012; Simpson et al., 2015), as well as among other fossil mammals (e.g., Anthony and Richards, 1924; Averianov and Archibald, 2013; Kerber et al., 2014). While the terms ‘crenulation’ or ‘wrinkle’ appear regularly in the literature, they are rarely explicitly defined. When defined, there are conflicting ideas as to what constitutes the trait. For example, Swindler and Ward (1988, p. 405) define crenulations as a collective term for the “various crests and grooves” on the “occlusal surfaces of the molars of many mammalian groups.” Additionally, they define the deflecting wrinkle as only “one of many occlusal crenulations occurring on hominoid molars” (Swindler and Ward, 1988, p. 406). https://doi.org/10.1016/j.jchb.2018.06.001 Received 5 May 2017; Accepted 28 May 2018 ⁎ Corresponding author at: Department of Anthropology, University of Nevada, Reno, 1664 No Virginia, Reno, NV 89557/0096, USA. Fax: +1 775 682 7693. E-mail address: mpilloud@unr.edu (M.A. Pilloud). HOMO - Journal of Comparative Human Biology xxx (xxxx) xxx–xxx 0018-442X/ © 2018 Elsevier GmbH. All rights reserved. Please cite this article as: Pilloud, M.A., HOMO - Journal of Comparative Human Biology (2018), https://doi.org/10.1016/j.jchb.2018.06.001