Sexual dimorphism of canine teeth of small dogs

Lorber, Mortimer; Alvo, G.; Zontine, William J.

doi:10.1016/0003-9969(79)90017-7

Cited by 6 publications

(4 citation statements)

References 13 publications

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“…By contrast, knowledge about whether and how sex hormones affect tooth morphology in humans is limited. There is indirect evidence of tooth development being affected by circulating sex and growth hormones (Garn et al, 1965a;Lorber et al, 1979). Androgens also have been implicated in tooth development in spotted hyenas (Frank et al, 1991) and in sexual dimorphism in molar tooth mass of mice (Heller and Blecher, 1982).…”

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Increased tooth crown size in females with twin brothers: Evidence for hormonal diffusion between human twins in utero

1999

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In rodents, the position of a fetus in utero is associated with the expression of sexually dimorphic traits. This phenomenon has been explained by prenatal diffusion of sex hormones among litter mates. To test for such effects in humans, female‐male twin pairs provide a natural experiment. The size of dental crowns is a sexually dimorphic trait which can be measured with a high degree of reliability. Thus, two crown diameters of 28 permanent teeth were recorded for 56 opposite‐sexed (OS) and 242 same‐sexed (SS) twin pairs, and 150 singletons. Comparisons of OS twins with SS twins and singletons within each sex reveal that OS females have consistently larger teeth (on average) than other females, while there is no consistent difference between OS and SS twin males. It is proposed that diffusion of sex hormones from male to female co‐twins in utero may account for the increased tooth size in OS females. This study is one of the first to report such an effect on a morphological variable in humans. The finding that the maxillary canine, one of the most sexually dimorphic teeth, exhibits the least effect in OS female twins, suggests that prenatal sex hormone levels may have less impact on sexual dimorphism in the maxillary canines than in other permanent teeth. Am. J. Hum. Biol. 11:577–586, 1999. © 1999 Wiley‐Liss, Inc.

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Increased tooth crown size in females with twin brothers: Evidence for hormonal diffusion between human twins in utero

1999

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“…Canine size is sexually dimorphic in many mammals. Lorber et al (1979) proposed that sex hormones influence sexual dimorphism of canines in 1 3 dogs; this is reasonable, but it remains to be demonstrated experimentally. If canine di morphism in tayassuids is controlled by ste roid sex hormones, a new correlation be tween canines and zygomata could have been effected by placing phenotypic expression of the zygomatic process under the control of the same hormones.…”

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Evolution of sexually dimorphic characters in peccaries (Mammalia, Tayassuidae)

Wright

1993

Paleobiology

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Cladistic analysis of osteological and dental characters in a monophyletic group of Miocene and younger tayassuids demonstrates a pattern of changes in the degree of sexual dimorphism in canine tooth diameter and zygomatic arch width, and in phenotypic correlations between these characters. Primitively, tayassuids have canine teeth that are sexually dimorphic and discretely bimodal in size, and zygomatic arches that are narrow in both sexes. Many late Miocene and Pliocene tayassuids have broad, winglike zygomatic processes. In some species, these processes are large in both sexes, but in others, those of females are much smaller than those of males. The presence of large processes in both sexes is primitive relative to the condition of strong sexual dimorphism. In five separate clades, the zygomatic processes of both sexes become reduced in size, and the degree of sexual dimorphism in canine size becomes reduced as well. The pattern is congruent with predictions derived from a theoretical model of the evolution of sexual dimorphism, and it further indicates the emergence of a new phenotypic correlation between two previously uncorrelated characters, canine size and zygoma size. The advent of this new correlation coincides with the advent of pronounced sexual dimorphism in zygomatic processes. Although such a pattern could be explained by genetically modifying phenotypic expression of homologous characters in one sex or the other, an epigenetic modification of expression is equally plausible: the evolution of sexual dimorphism in homologous characters could be accomplished by placing phenotypic expression of an originally monomorphic character under the control of steroid sex hormones. This hypothesis is consistent with evidence from many vertebrate groups, and it provides testable predictions.

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“…This observed variation of the canines between populations has been explained by the simpler morphology (as compared to the rest of the dentition) and small size (Szuma 2000). Furthermore, the role of hormones in canine development and the variation in sexual dimorphism has also been speculated about (Lorber et al 1979), although the role of sex hormones in dental development is not clear (e.g., Guatelli-Steinberg et al 2008). As a likely result, in general the canine may be a good indicator of selection caused by competition-a result that yet needs to be assessed for these canids.…”

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The canine counts! Significance of a craniodental measure to describe sexual dimorphism in canids: Golden jackals (Canis aureus) and African wolves (Canis lupaster)

et al. 2021

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Sexual dimorphism is a widespread phenomenon among mammals, including carnivorans. While sexual dimorphism in golden jackals (Canis aureus) has been analysed in the past, in the related and apparently convergent canid, the African wolf (Canis lupaster), it is poorly studied and showed to be relatively small. Previously, sexual size dimorphism (SSD) research in these species was mostly based on skull and body measurements. In our study, we also included dental measurements, namely the diameter of the canine. We used 11 measured sections of 104 adult specimens, comprising 61 golden jackal and 43 African wolf skulls. Data analyses were carried out through logistic regression and conditional inference trees (CIT). To compare the results of SSD to other species, sexual dimorphism indices (SDI) were calculated. Golden jackals and African wolves show significant sexual size dimorphism, both in cranial and dental size. The logistic regression revealed that the mesiodistal diameter of the upper canine is most effective in discerning the sexes. The difference in the calculated SDI of the canine diameter between the sexes amounted to 8.71 in golden jackals and 14.11 in African wolves, respectively—with regional diversity. Thus, the canine diameter is an important measure to investigate SSD as well as an easy tool to apply in the field.

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Sexual dimorphism of canine teeth of small dogs

Cited by 6 publications

References 13 publications

Increased tooth crown size in females with twin brothers: Evidence for hormonal diffusion between human twins in utero

Increased tooth crown size in females with twin brothers: Evidence for hormonal diffusion between human twins in utero

Evolution of sexually dimorphic characters in peccaries (Mammalia, Tayassuidae)

The canine counts! Significance of a craniodental measure to describe sexual dimorphism in canids: Golden jackals (Canis aureus) and African wolves (Canis lupaster)

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