Human adults often show a preference for scarce over abundant goods. In this paper, we investigate whether this preference was shared by 4‐ and 6‐year‐old children as well as chimpanzees, humans’ nearest primate relative. Neither chimpanzees nor 4‐year‐olds displayed a scarcity preference, but 6‐year‐olds did, especially in the presence of competitors. We conclude that scarcity preference is a human‐unique preference that develops as humans increase their cognitive skills and social experiences with peers and competitors. We explore different potential psychological explanations for scarcity preference and conclude scarcity preference is based on children's fear of missing out an opportunity, especially when dealing with uncertainty or goods of unknown value in the presence of competitors. Furthermore, the results are in line with studies showing that supply‐based scarcity increases the desirability of hedonic goods, suggesting that even as early as 6 years of age humans may use scarce goods to feel unique or special.

Demonstrations of nonhuman ability to share resources and reciprocate such sharing seem contingent upon the experimental paradigm used (note Horner et al. in PNAS 108:13847-13851, 2011). Here, such behaviour in Grey parrots (Psittacus erithacus) was tested in two experiments, both designed to avoid possible issues involving apparatus complexity, visible reward options, and physical competition and/or limited communication between subjects. In both studies, two birds, working in dyads, took turns in choosing one of four different coloured cups with differing outcomes: empty (null, nonrewarding), selfish (keeping reward for oneself), share (sharing a divisible reward), or giving (donating reward to other). In Experiment 1, each bird alternated choices with a conspecific; in Experiment 2, each bird alternated with the three humans with different specific intentions (selfish, giving, or copying bird's behaviour). In both experiments, birds could learn to cooperatively reward a partner at little cost to themselves-by sharing-and potentially maximize overall reward by reciprocating such sharing. Experiment 1 results differed depending upon which bird began a session: Only our dominant bird, as follower, was willing to share. In Experiment 2, birds' responses tended towards consistency with human behaviour. Our dominant bird was willing to share a reward with a human who was willing to give up her reward, was selfish with the selfish human, and tended towards sharing with the copycat human; our subordinate bird tended slightly towards increased sharing with the generous human and selfishness with the selfish human, but did not change behaviour with the copycat.

Chimpanzees hunt cooperatively in the wild, but the factors influencing food sharing after the hunt are not well understood. In an experimental study, groups of three captive chimpanzees obtained a monopolizable food resource, either via two individuals cooperating (with the third as bystander) or via one individual acting alone alongside two bystanders. The individual that obtained the resource first retained most of the food but the other two individuals attempted to obtain food from the "captor" by begging. We found the main predictor of the overall amount of food obtained by bystanders was proximity to the food at the moment it was obtained by the captor. Whether or not an individual had cooperated to obtain the food had no effect. Interestingly, however, cooperators begged more from captors than did bystanders, suggesting that they were more motivated or had a greater expectation to obtain food. These results suggest that while chimpanzee captors in cooperative hunting may not reward cooperative participation directly, cooperators may influence sharing behavior through increased begging.