Age-Related Changes in Marmoset (Callithrix jacchus) Feeding Behavior and Physiology: Insights of Masticatory and Swallowing Functions

The common marmoset (Callithrix jacchus) is a valuable model for studying aging due to its physiological and social similarities to humans, including shared susceptibilities to age-related diseases. However, the effects of healthy aging on marmoset mastication and swallowing are poorly understood, despite their importance for modeling human aging and understanding marmoset ecology and longevity (efficient food processing impacts foraging success and predation risk). Given their specialized diet, dental adaptations, and relatively long lifespan compared with other biomedical models commonly used, like rodents, understanding how elderly marmosets maintain feeding efficiency is particularly important, yet lifespan research on their feeding physiology is scarce. Using cineradiography (with a microfocal X-ray source and beryllium image intensifier), we examined masticatory and swallowing physiology across the marmoset lifespan (1 month to 19 years) in 26 healthy individuals, analyzing 45 recordings (80 feeding events, 784 swallows). Our study revealed a developmental trajectory in marmoset chewing and swallowing, from infancy to old age, characterized by progressively refined handling of larger food portions and boluses. We identified distinct anatomical, functional, and behavioral differences in feeding physiology among age groups. Elderly marmosets exhibited significantly faster feeding rates than infants and adults, consuming larger portions and forming larger boluses, requiring fewer mastications and swallows, likely reflecting age-related adaptations. Notably, old and very old marmosets showed comparable feeding efficiency, suggesting compensatory mechanisms to maintain function despite age-related challenges (e.g., tooth loss or muscle weakness) and may contribute to longevity. The consistent pattern of esophageal retention across age groups indicates this pattern is likely typical for the species. This study establishes baseline feeding characteristics for marmosets, reinforcing their value as a translational aging model and enhancing their utility for investigating age-related changes in human chewing and swallowing, including dysphagia. Future research should explore the underlying mechanisms and functional implications of these changes.