Some students of animal behavior claim that empathy is not restricted to humans as the definition implies. Examples include dolphins saving humans (sympathy) from drowning or from shark attacks, and a multitude of behaviors observed in primates, both in captivity and in the wild. See, for instance, the popular book The Ape and the Sushi Master by Frans de Waal. Rodents have been shown to demonstrate empathy for cagemates (but not strangers) in pain