Vervet monkeys (Loskop, South-Africa)

 a member of Picnic Group (photo R. Noë)

Cécile Fruteau

Cécile's study was supported by a grant of the NWO in the framework of the Evolution and Behaviour programme

Riccardo Pansini

Riccardo's study was supported by the GEBACO-programme

Cooperation and economic behaviour are the main topics of our research on vervet monkeys in the Loskop Dam Nature Reserve (Mpumalanga Province, South-Africa).


the home range of Picnic Group

We changed the 'partner value' of one or more individuals experimentally by allowing them to operate food dispensers. Changes in partner value are measured as shifts in grooming ratios.

A first study was done by Cécile Fruteau, who did her PhD under supervision of the economist Eric van Damme (CentER, University van Tilburg, The Netherlands) and me.

Cécile allowed one low-ranking female in each group to open a box containing a reward for herself and her group members. The result was a dramatic shift in grooming ratios in favour of this 'first provider'. The market effect we are interested in became apparent when a second provider was added: the grooming ratios of the first provider dropped halfway back in the direction of baseline levels.

Fruteau etal 2009 market experiment (PNAS)

A provider opening a food container (photo & video by Cécile Fruteau - Loskop Dam Nature reserve, South-Africa)

Cécile Fruteau obtained her PhD from the University of Tilburg (The Netherlands) on December the 21st, 2010. Published chapters of this thesis include:
  • Fruteau, C., Lemoine, S., Hellard, E., van Damme, E. & Noë, R. 2011. When females trade grooming for grooming: testing partner control and partner choice models of cooperation in two primate species. Animal Behaviour, 81, 1223-1230. pdf
  • Fruteau, C., van de Waal, E., van Damme, E. & Noë, R. 2011. Infant access and handling in sooty mangabeys and vervet monkeys. Animal Behaviour 81, 153-161 pdf
  • Fruteau, C., Range, F. & Noë, R. 2010 Infanticide risk and infant defence in multi-male free-ranging Sooty Mangabeys, Cercocebus atys. Behavioural Processes 83, 113-118 pdf
  • Fruteau, C., Voelkl, B., van Damme, E., & Noë, R.  (2009) Supply and demand determine the market value of food providers in wild vervet monkeys. Proceedings of the National Academy of Science 106, 12007-12012 PNAS Open Access
  • Fruteau, C., van Damme, E., & Noë, R. (2013). Vervet monkeys solve a multiplayer “Forbidden Circle Game” by queuing to learn restraint. Current Biology, 23(8), 665-670 pdf (see the page "Forbidden Circle Game" for a PowerPoint on this topic)

---  Follow-up  ---

In a follow-up study, Riccardo Pansini created a situation in which two individuals, belonging to two trader classes of different size, had to cooperate to obtain a reward. This study hasn't quite developed as planned, but some interesting results emerged nevertheless:

  • Pansini, R. 2011. Induced cooperation to access a shareable reward increases the hierarchical segregation of wild vervet monkeys. PLoS ONE, 6, e21993


The Loskop research site is run by the Applied Behavioural and Ecosystems Research Unit (ABEERU) of the University of South-Africa (UNISA)