Vertebrate consumption is rare among non-human primates, whereas it played a very important role in the evolution of our species. Determining when and why other primates exploit these resources can help us understand the consumption of meat by our ancestors.

The study presents the most extensive record published to date of meat consumption by bearded capuchin monkeys (Sapajus libidinosus), a South American monkey species known for its habitual use of stone tools. The findings provide a comparative model for considering the role that the consumption of small vertebrates may have played in human evolution. The research is based on 45 months of observations of two wild groups of bearded capuchins living at Fazenda Boa Vista, in the state of Piauí, north-eastern Brazil. Over more than 5,000 hours of observation, researchers recorded 446 instances of vertebrate consumption, corresponding to an average predation rate of 6.34 events per 100 hours. The prey hunted consisted mainly of reptiles — particularly lizards, and occasionally snakes and iguanas — followed by mammals, especially rodents. The extensive list also included birds, bats and opossums.

“The findings show that the consumption of mammals and lizards is a regular component of this population’s diet, just as their use of stones and anvils to open small coconuts and other hard-shelled fruits is habitual,” says Elisabetta Visalberghi of CNR-ISTC. “Predation is more frequent among males than females and among adults than juveniles. Moreover, when the availability of fruit and insects decreases, the consumption of small vertebrates increases. These prey are therefore not simply an occasional diversion, but an important source of energy.” The way in which the prey are consumed is also noteworthy. The brain and internal organs are extracted and eaten before other parts of the body. These tissues are rich in nutrients and are chewed very quickly, whereas the muscle tissue requires longer processing. “Rapid energy acquisition is certainly advantageous when prey is being shared with other group members, or when there is a risk that someone else may take it,” Visalberghi continues.

“Moreover, observing how capuchins incorporate small vertebrates into their diet can help us better understand certain stages in the evolution of human predation,” adds Noemi Spagnoletti, a researcher at Sapienza University of Rome and co-leader of the study. “Studying these behaviours in primates therefore provides us with new insights into how the subsistence strategies of early humans may have evolved".

Before the emergence of the so-called human predatory pattern, characterised by the regular exploitation of animals of a size equal to or greater than that of the predator, small vertebrates may have represented an important source of nutrients for hominins, particularly during periods when other resources were scarce. Exploiting these animals is simpler, less risky and less costly than hunting and consuming larger prey. It is therefore entirely plausible that the exploitation of small vertebrates preceded and accompanied the exploitation of larger animals. The study therefore calls for greater attention to evidence of small-vertebrate consumption in fossil faunal assemblages, in order to assess the role these resources may have played during the early stages of the evolution of human predation.

The research also highlights the importance of long-term field studies for understanding the dietary strategies of long-lived primates characterised by a high degree of behavioural flexibility.

The international collaboration involved, in addition to Sapienza University of Rome and the National Research Council (CNR), Gorongosa National Park in Mozambique, the University of São Paulo in Brazil, University of Porto, University of the Algarve and University of Coimbra in Portugal, the University of Oxford in the United Kingdom, and the Pontifical Catholic University of Chile. Noemi Spagnoletti’s field research, which began during her PhD at Sapienza in collaboration with the CNR-ISTC Primate Centre in Rome, was also supported by a Sapienza scholarship for advanced training abroad.

References: Spagnoletti, N et al., Small vertebrate consumption by capuchin monkeys (Sapajus libidinosus): Insights into the human predatory pattern. PLOS ONE (2026).

DOI: 10.1371/journal.pone.0355204.