Machiavellian intelligence hypothesis

In primatology, the Machiavellian intelligence hypothesis describes the capacity of animals to manoeuvre in complex social groups.^[1]^[2]^[3] It is also known as the "social brain" or "social intelligence" hypothesis.

This hypothesis posits that enlarged brains and distinctive cognitive abilities of primates have evolved via intense social competition in which social competitors developed increasingly sophisticated strategies as a means to achieve higher social and reproductive success.^[4]

Overview

Origin of the term

The use of "Machiavellian" originates from the primatologist Frans de Waal, who discussed chimpanzees' complex social maneuverings in his book Chimpanzee Politics (1982).^[5]^[6] However, foundations for the concept can be traced to lemur researcher Alison Jolly. While conducting field research in the 1960s, Jolly noticed that lemurs lacked monkeys' ability to manipulate objects but demonstrated similarly strong social skills. At the time, it was commonly believed that solving technical and foraging challenges is what fueled the advancement of primate intelligence.^[7] Jolly found that, on the contrary, social skills preceded technical abilities and thus played a more central role.

Primatologists Nicholas Humphrey, Andrew Whiten and Richard Byrne developed this theory further.^[8]^[9]^[10] Byrne and Whiten edited two volumes that compiled interdisciplinary research exploring the theme, Machiavellian Intelligence: Social Expertise and the Evolution of Intellect in Monkeys, Apes, and Humans (Oxford University Press, 1988) and Machiavellian Intelligence II: Extensions and Evaluations (Cambridge University Press, 1997). They observed that primates, particularly great apes, displayed intricate social behaviors such as alliance formation, deception, and reconciliation. These behaviors seemed to require cognitive abilities beyond what was necessary for basic survival tasks like foraging or avoiding predators.

Relations with other research

As a concept, it is also conflated with, and mistaken for the Machiavellianism personality construct, which focuses on the affective-interpersonal traits of human beings, such as unemotionality and exploitativeness, while Machiavellian Intelligence deals with the social behaviors of primates and is not focused on immoral actions.^[11]

Primate social behavior

In Chimpanzee Politics, de Waal describes the various social behaviors among chimpanzees, focusing specifically on interactions such as coat hair grooming. The first section explains the "submissive greeting," where a more submissive chimpanzee acknowledges a dominant one through pant-grunting, bobbing, or bringing objects like leaves or sticks. Dominant chimps respond by making themselves appear larger, while the submissive one may crouch or present their backside for inspection. Among adult males, dominance can be further exaggerated by actions like stepping over the subordinate, reinforcing social rank through physical gestures.^[12]

Another part of the book highlights grooming as the most frequent social activity in the Arnhem colony. Chimpanzees gather in grooming clusters, carefully attending to each other's hair while making soft sounds. This behavior strengthens social bonds and demonstrates their enjoyment of being groomed. Meanwhile, young chimpanzees, especially those slightly older, engage in energetic play, sometimes disrupting grooming groups by running through them or throwing sand, showing the coexistence of structured social order and youthful exuberance within the chimpanzee community.^[13]

Chimpanzees try to detect early signs of hostility to avoid conflict. Female aggression is described as sudden and unpredictable, while male aggression builds up gradually through body swaying, raised hackles, increased vocalizations, and ultimately an attack.^[14]

Criticisms

Researchers Shirley C. Strum, Deborah Forster and Edwin Hutchins state that "We suggest that Machiavellian intelligence may be a misnomer." and that "primate social complexity appears to be an intricate tapestry of competition and cooperation, of aggression and reconciliation, of nonaggressive social alternatives, and of behaviors and relationships that cannot be easily categorized into simple opposites."^[15] Critics also cite that the "exceptions" in the form of small-brained primates in very large groups typically eat abundant but nutrient-poor foods (such as geladas that eat grass), as predicted by the food-based model, and argue that the higher individual need for nutrients put on by large brains causes groups to become smaller if the species have the same degree of digestive specialisation and environmental availability of food.^[16]^[17]

References

^ Byrne, Richard W.; Whiten, Andrew (1990). "Machiavellian Intelligence: Social Expertise and the Evolution of Intellect in Monkeys, Apes, and Humans". Behavior and Philosophy. 18 (1): 73–75.
^ Byrne, Richard W. (2022). "Machiavellian Intelligence". Encyclopedia of Animal Cognition and Behavior. pp. 4033–4038. doi:10.1007/978-3-319-55065-7_781. ISBN 978-3-319-55064-0.
^ Gavrilets, Sergey; Vose, Aaron (2006-11-07). "The dynamics of Machiavellian intelligence". Proceedings of the National Academy of Sciences. 103 (45): 16823–16828. arXiv:q-bio/0610002. Bibcode:2006PNAS..10316823G. doi:10.1073/pnas.0601428103. ISSN 0027-8424. PMC 1636539. PMID 17075072.
^ Vose, Aaron; Gavrilets, Sergey (2006-11-07). "The dynamics of Machiavellian intelligence". Proceedings of the National Academy of Sciences. 103 (45): 16823–16828. arXiv:q-bio/0610002. Bibcode:2006PNAS..10316823G. doi:10.1073/pnas.0601428103. ISSN 0027-8424. PMC 1636539. PMID 17075072.
^ Chimpanzee Politics, pg 4
^ Waal, Frans de; Waal, Frans B. M. (2007-09-30). Chimpanzee Politics: Power and Sex Among Apes. JHU Press. ISBN 9780801886560.
^ Hopper, Linda; van de Waal, Erica; Caldwell, Christine (2018). "Celebrating the Continued Importance of "Machiavellian Intelligence" 30 Years On". Journal of Comparative Psychology. 132 (4): 427–431.
^ Byrne, Richard W. (2018). "Machiavellian intelligence retrospective". Journal of Comparative Psychology. 132 (4): 432–436. doi:10.1037/com0000139. hdl:10023/16539. PMID 30451526.
^ Humphrey, N. The social function of the intellect
^ Whiten, A., & Byrne, R. W. (Eds.). (1997). Machiavellian intelligence II: Extensions and evaluations (Vol. 2). Cambridge University Press.
^ "MI should therefore not be conflated – though it sometimes has been – with the human personality trait of “Machiavellianism” (Christie and Geis 1970) which refers specifically to an ability to detach from conventional morality and emotionality in order better to deceive and manipulate other people. MI is not about morality, and not restricted to “nasty” actions."
Byrne, R.W. (2022). Machiavellian Intelligence. In: Vonk, J., Shackelford, T.K. (eds) Encyclopedia of Animal Cognition and Behavior. Springer, Cham. https://doi.org/10.1007/978-3-319-55065-7_781
^ Chimpanzee Politics, p 7
^ Chimpanzee Politics, pg. 77-78
^ Waal, Frans B. M. (10 April 2000). Chimpanzee Politics: Power and Sex Among Apes. JHU Press. ISBN 978-0-8018-6336-3.
^ Strum, Shirley C.; Forster, Deborah; Hutchins, Edwin (1997), Whiten, Andrew; Byrne, Richard W. (eds.), "Why Machiavellian intelligence may not be Machiavellian", Machiavellian Intelligence II: Extensions and Evaluations, Cambridge: Cambridge University Press, pp. 50–85, ISBN 978-0-521-55087-1, retrieved 2025-03-29
^ DeCasien, Alex R.; Williams, Scott A.; Higham, James P. (27 March 2017). "Primate brain size is predicted by diet but not sociality". Nature Ecology & Evolution. 1 (5): 112. Bibcode:2017NatEE...1..112D. doi:10.1038/s41559-017-0112. PMID 28812699. S2CID 205564046.
^ Venditti, Chris (27 March 2017). "Evolution: Eating away at the social brain". Nature Ecology & Evolution. 1 (5): 122. Bibcode:2017NatEE...1..122V. doi:10.1038/s41559-017-0122. PMID 28812702. S2CID 7207012.