They move at a more relaxed pace than spider monkeys and seem to have fairly peaceful inter-group interactions. Alfred Russel Wallace had this to say about them - "Closely allied to the last [spider monkeys] are the woolly monkeys, which have an equally well-developed prehensile tail, but better proportioned limbs, and a thick woolly fur of a uniform grey or brownish colour. They have well formed fingers and thumbs, both on the hands and feet, and are rather deliberate in their motions, and exceedingly tame and affectionate in captivity. They are great eaters, and are usually very fat... having a delicate constitution [they], seldom live long in Europe." He goes on in another piece - "In the upper Amazon they are the species most frequently seen tame, and are great favourites, from their grave countenances, more resembling the human face than those of any other Monkeys, their quiet manners, and the great affection and docility they exhibit." Watching them you can immediately understand why he seemed so fond of the species.