Differences in the deployment of altruism in human and non-human primate groups raise two different questions in this article. This article considers some of the factors that may limit the extent of cooperation in non-human primate groups. In particular, it focuses on the evidence for the features that are associated with altruistic behaviour in humans: the capacity for empathy, the existence of moral sentiments, and the concern for the welfare of others. The article also defines cooperation as equivalent to the biological definition of altruism, and uses these terms interchangeably. It distinguishes between empathy and sympathy. The definition of empathy corresponds to Stephanie Preston and Frans de Waal's concept of ‘cognitive empathy’. While one often conflates empathy and sympathy, the two can be uncoupled. Thus, empathy is a necessary, but not sufficient, condition for sympathy.