Hand preferences and differences in extractive foraging in seven capuchin monkey species

Area of Science:

• Primate behavior
• Animal cognition
• Comparative psychology

Background:

• Tool use and extractive foraging are hypothesized drivers of hand preference in primates.
• Robust capuchins (Sapajus) are more specialized for extractive foraging than gracile capuchins (Cebus).
• Previous assumptions linked tool use to right-hand preference.

Purpose of the Study:

• To investigate hand preference and extractive foraging rates in seven capuchin species.
• To test the hypothesis that dry habitat capuchins show higher extractive foraging and right-hand preference.
• To examine the relationship between tool use, extractive foraging, and lateralization in Sapajus.

Main Methods:

• Tube task assessing hand preference in 152 individuals.
• Extractive foraging task assessing foraging behavior in 212 individuals.
• Focal and scan sampling used for data collection in captive settings.

Main Results:

• Sapajus libidinosus exhibited significant left-hand preference, contrary to predictions.
• Sapajus robustus and S. flavius showed right-hand preference.
• Gracile capuchins displayed a stronger left-hand bias than robust capuchins.
• Extractive foraging rates varied significantly across species, with S. xanthosternos, S. flavius, and S. robustus foraging more.

Conclusions:

• The link between tool use and right-hand preference is more complex than previously thought, especially in Sapajus.
• Population-level left-handedness was observed in S. libidinosus, a tool-using species.
• Differences in food resources and selective pressures, particularly reliance on bimanual feeding and complex foraging, likely explain variations in hand preference.