Negotiators aka Chimpanzees

New research has demonstrated that one of our two closest primate relatives, the chimpanzee can settle conflicts of interest over resources in mutually satisfying ways – even without the social norms of equity, planned strategies of reciprocity, and the complex communication characteristic of human negotiation.

Dr. Alicia Melis from the Max-Planck-Institute for Evolutionary Anthropology, Germany has been conducting various experiments with chimpanzees. An article recently published in the journal “Evolution and Human Behavior” authored by Dr. Melis has shed light on the various intricate negotiating capabilities of chimpanzees.

Basic cooperation among social species in aspects like travel direction or activity timing has long been documented however solving conflicts on resources like food have had very little research. Dr. Melis and team, trained a group of chimps on various aspects including the importance of cooperation. The chimps were taught that cooperation benefits both. The chimps were also paired containing a dominant partner and a subordinate partner. Most of these chimps had been already involved in cooperation oriented experiments. Here is a clip which demonstrates how chimps are demonstrated the importance of cooperation.

Dr. Melis split the study into 2 experiments. In the first set of experiment, the chimps were presented with an inequity condition (wherein the chimps could either agree on an equal share of food or settle for a selfish option ie., the dominant chimp gets a whole banana as compared to a slice or an altruistic option ie., dominant gets the slice) and a control condition (wherein an equal share is not possible and thus only a selfish or altruistic option is possible). In the second set of experiment, the same inequity condition was used along with a double inequity condition (wherein the chimps could agree on an equal share or settle for a selfish option, which yields two full bananas for the dominant while the subordinate gets a slice or an altruistic option of the dominant chimp getting the slice). Given below is a video which just demonstrates the setup. Note that what you see in the video is not suggestive of the final outcomes of the experiment.

In all of the experiments, the dominant was the first to enter into the room and thus had the choice to pick the rope it wanted, interpreted as an offer made by the dominant chimp. The subordinate chimp then enters the room and can either choose the rope on the other end of the tray (offered), thus signaling the acceptance of the offer, can go to the other tray signaling a different counter offer or just even refuse to any solution.

Several aspects such as the offer made, time taken to make an offer, acceptance, time taken to accept, etc were recorded. The final results of experiment 1 (shown in the table) demonstrated that the dominant chimps significantly offered selfish options. However, based on the other options available acceptance of the selfish offer varied (ie., in the inequity condition, as an equal option was avaliable, 55% of the selfish offers were refused by the subordinate, while in the control option, realising that no equal option is possible and that the dominant would not give the larger portion, the subordinates accepted 94% of the selfish offers. It should be here noted that refused offers landed up in either a newer agreement or a breakdown. One other important observation here is that of the 37% equal offers made by the dominants, 87% of them were accepted. This clearly signals, that the subordinates were well aware that this was practically the best offer they could get. In case of experiment 2, the inequity condition had similar results like experiment 1, however in the double inequity condition, the selfish offers drastically increased (90% vs 63% in the inequity condition of experiment 2) and the conversion of the double inequity selfish offer to an equal offer also doubled, which shows a clear sign of the dominant trying to get the largest possible share eventually settling to a lower deal rather than landing up with nothing.

Given below is one more video which shows a trial where negotiation happens. The two cameras on the top show the room from which the pair can access the unequal tray. The top left camera is placed showing the position from which the subject would obtain the smallest reward (a banana slice), whereas the top right camera shows the position from which the subject would obtain the largest reward (a whole banana). The camera on the bottom left shows the room from which the subjects can access the equal tray (half banana per plate). The trial starts when the dominant female enters the room and positions herself in front of the largest reward of the unequal tray (Top right camera), making thus a ‘selfish’ offer to subordinate female. The subordinate female, who enters the testing rooms some seconds later, joins the dominant partner briefly and touches the rope of the unequal tray (Top left camera) but refuses to pull and goes to the equal tray (Bottom left camera at time: 9:02:21). The trial ends when the dominant female joins the subordinate and they both pull the equal tray containing half banana per plate (Bottom left camera at time: 9:02:48).