Talon cusp expression in Cayo Santiago rhesus macaques (Macaca mulatta)

Area of Science:

• Primatology
• Dental Morphology
• Genetics

Background:

• Talon cusps are an uncommon dental anomaly observed in various primate species.
• Understanding their prevalence and inheritance patterns can provide insights into dental development.

Purpose of the Study:

• To document the prevalence of maxillary central incisor talon cusps in Cayo Santiago rhesus monkeys (Macaca mulatta).
• To determine if talon cusp presence occurs at equivalent frequencies across different matrilines.

Main Methods:

• Logistic regression analysis was employed to analyze cusp presence versus absence.
• Data were collected from 170 rhesus monkeys (82 females, 78 males) across seven matrilines.
• Observations were conducted blindly regarding matriline and sex.

Main Results:

• Talon cusps were present in 9.4% of the sampled rhesus monkeys.
• Cusp frequencies varied by matriline, ranging from 0% to 19.1%.
• Matriline 076 showed a significantly higher frequency of talon cusps compared to other matrilines; no significant sex-based difference was found.

Conclusions:

• The talon cusp is a rare trait in rhesus monkeys, consistent with findings in humans and baboons.
• The elevated prevalence in Matriline 076 suggests a possible genetic influence on talon cusp expression in this species.