Sorry, my BS detector just went off big time. No criticism of you, Ohnai, but is there any link to the data? Animal behaviorists are right up there with Parapsychologists when it comes to 'interpreting' their own data.
To add to Ohnai's links above;
FB de Waal has done a lot of work on cooperation in capuchins, and he is definitely not an anthropomorphism-prone animal behaviorist of the type you criticize. "de Waal FB" put into
http://www.pubmed.org will give you plenty of interesting abstracts. I'll list a few interesting refs below, but to waylay some of your specific concerns:
I have to wonder what kind of reward the monkeys get from their researchers if they do the 'experiment' (read 'routine') correctly.
The researchers are not training these monkeys to do 'tricks'. The only reward is the shared food reward that they work to get.
Does the monkey share 'about' 50% of the nuts EVERY time? Or just once in a while. Or just on that program?... I also have to wonder how many times 'rock monkey' ended up throwing his feces at 'nut monkey' out of frustration when 'nut monkey' ate all the goods.
Statistical analyses are applied to the research like any other - if non-cooperative feces-throwing confounded results, they would not be significant, and thus not publishable. In many papers certain groups (age, sex) excel at a task while others fail, and the failings of those groups are reported.
Ideally I'd like to see how many times the experiment was run, how much help the monkeys had 'learning' to cooperate, how frequently cooperation and sharing occurred, etc.
The monkeys are not taught to cooperate - they are often naive to the experimental conditions, or have simply been shown how to manipulate a situation to get the food (but not shown how to cooperate). Check some of the sources below for specifics - the one Ohnai mentioned is not among them, by the way...
It may also ease your mind to realize that cooperation and sharing is part of natural social interactions in wild monkeys and apes. The degree of sharing is proportional to degree of relation and labor put toward getting the food.
Nature. 2003 Sep 18;425(6955):297-9.
Monkeys reject unequal pay.
Brosnan SF, De Waal FB.
During the evolution of cooperation it may have become critical for individuals to compare their own efforts and pay-offs with those of others. Negative reactions may occur when expectations are violated. One theory proposes that aversion to inequity can explain human cooperation within the bounds of the rational choice model, and may in fact be more inclusive than previous explanations. Although there exists substantial cultural variation in its particulars, this 'sense of fairness' is probably a human universal that has been shown to prevail in a wide variety of circumstances. However, we are not the only cooperative animals, hence inequity aversion may not be uniquely human. Many highly cooperative nonhuman species seem guided by a set of expectations about the outcome of cooperation and the division of resources. Here we demonstrate that a nonhuman primate, the brown capuchin monkey (Cebus apella), responds negatively to unequal reward distribution in exchanges with a human experimenter. Monkeys refused to participate if they witnessed a conspecific obtain a more attractive reward for equal effort, an effect amplified if the partner received such a reward without any effort at all. These reactions support an early evolutionary origin of inequity aversion.
PMID: 13679918
Anim Behav. 2000 Oct;60(4):523-529.
Capuchins do cooperate: the advantage of an intuitive task.
Mendres KA, de Waal FB
We used a cooperative pulling task to examine proximate aspects of cooperation in captive brown capuchin monkeys, Cebus apella. Specifically, our goal was to determine whether capuchins can learn the contingency between their partner's participation in a task and its successful completion. We examined whether the monkeys visually monitored their partners and adjusted pulling behaviour according to their partner's presence. Results on five same-sex pairs of adults indicate that (1) elimination of visual contact between partners significantly decreased success, (2) subjects glanced at their partners significantly more in cooperative tests than in control tests in which no partner-assistance was needed, and (3) they pulled at significantly higher rates when their partner was present rather than absent. Therefore, in contrast to a previous report by Chalmeau et al. (1997, Animal Behaviour, 54, 1215-1225), cooperating capuchins do seem able to take the role of their partner into account. However, the type of task used may be an important factor affecting the level of coordination achieved. Copyright 2000 The Association for the Study of Animal Behaviour.
PMID: 11032655
Anim Behav. 2000 Aug;60(2):253-261.
Attitudinal reciprocity in food sharing among brown capuchin monkeys.
de Waal FB.
Capuchin monkeys (Cebus apella) share food even if separated by a mesh restraint. Pairs of capuchins were moved into a test chamber in which one of them received apple pieces for 20 min, and the other received carrot pieces for the next 20 min. Previous research had shown a correlation between the rate of food transfer in both directions across female-female dyads. The present study confirmed this result. Reciprocity across dyads can be explained, however, by symmetry in affiliative and tolerant tendencies between two individuals, provided these tendencies determine food sharing. The present study was designed to exclude this symmetry-based explanation by testing each pair (N=16) of adult females on six separate occasions. There existed a significant covariation across tests of sharing in both dyadic directions, a result unexplained by relationship symmetry. Moreover, control procedures (i.e. testing of a food possessor without a partner, or testing of two individuals with the same food or two different foods at the same time) indicated that behaviour during food trials is not fully explained by mutual attraction or aversion. The monkeys take the quality of their own and the partner's food into account, and possessors limit transfers of high-quality foods. Instead of a symmetry-based reciprocity explanation, a mediating role of memory is suggested, and a mirroring of social attitude between partners. Copyright 2000 The Association for the Study of Animal Behaviour.
PMID: 10973728
This is real research, and not fubsy "look at what my monkey can do" tricks...
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