Hand preference in wild crab-eating capuchin monkeys (Sapajus libidinosus) in the coastal area of Northest Brazil.

Handedness is a fundamental human trait, although recent research, especially on nonhuman primates, has shown that it is displayed by other animals as well (e.g., chimpanzees, gorillas).

Mixed-species associations in cuxiús (genus Chiropotes).

Polyspecific or mixed-species associations, where two or more species come together to forage and travel as a unit, have been reported in many primate species. These associations appear to offer a number of benefits to the species involved including increased foraging efficiency and decreased risk of predation. While several researchers have suggested that cuxiús (genus Chiropotes) form mixed-species associations, previous studies have not identified the circumstances under which cuxiús form associations or whether they form associations more often than would be expected by chance.