Many people think that humans and chimpanzees are the only primates that eat meat. But scientists have known about widespread meat-eating in primates for decades. And, a recent review paper published in the Journal of Human Evolution has summarized all the data on meat-eating in primates to date. 

Over 89 species from 12 of the 17 families of of primates eat meat. These 89 species are scattered all over the world. Birds, including their eggs, are the most common primate prey, followed by reptiles, amphibians, mammals and even fish. Chimpanzees are the kings of variety, with 45 different vertebrate species appearing in their diets. 

But why to eat meat? Primates seem to be better off covering their calorie and protein needs by eating plants and invertebrates than by hunting. 

Most primates feed on meat sporadically, and it represents less than the 1 percent of the diet in almost all 89 species. There is no evidence that primates rely on meat for energy when other resources are scarce. The most likely explanation for meat-eating by primates at present is that meat provides micronutrients, such as vitamins and minerals, that are found in plants in only very small amounts. 

Human meat-eating is quite different from that of other primates. Meat is a key source of energy for many of us modern humans and our ancestors. And while other primates feed on prey much smaller than themselves, we hunt animals larger than ourselves. 

Throwing-weapons and other hunting tools play a considerable role in achieving this human feat. Some chimpanzees and capuchin monkeys do use tools like sticks for hunting. However, big game hunting from a distance seems to be exclusive to the human lineage.