When your neighbor asks to borrow a cup of sugar and you readily comply, is your positive response a function of the give and take that characterize your longstanding relationship? Or does it represent payment –– or prepayment –– for the cup of sugar you borrowed last week, or may need to borrow a month from now?
Two female chimpanzees take food from a male (center).
Credit: Adrian Jaeggi
Adrian Jaeggi, a postdoctoral researcher in anthropology at UC Santa Barbara, and a junior research fellow at the campus's SAGE Center for the Study of the Mind, is studying this question of reciprocity, using chimpanzees and bonobos as his test subjects. His findings appear in the current online issue of the journal Evolution & Human Behavior.
"The article focuses on the question of whether individuals do favors because they expect them to be reciprocated at some other time, and, more specifically, whether such exchanges have to happen immediately, or can take place over longer time spans," Jaeggi explained. "We studied the question in chimpanzees and bonobos –– our two closest living relatives –– and looked at the exchanges of grooming and food sharing, which are two common types of favors among these apes."
According to Jaeggi, while results of his research provide some evidence for immediate exchanges, they more strongly support the notion that favors are exchanged over long periods of time. Calculated exchanges, in which individuals keep a detailed score of past interactions, are much less common than the more loosely balanced exchanges that take place in stable relationships.
"In the chimp group we studied, we knew there was a lot of this long-term exchange," said Jaeggi. "We didn't find any evidence for a short-term effect." Chimpanzees live in stable social groups, he continued, and have a relatively long life span. They recognize others in the group, form long-term relationships, and associate with individuals who have helped them in the past."In the wild, for example, chimps hunt for smaller monkeys, and they commonly share the meat. It's similar to what hunters and gatherers do," Jaeggi said. "Our experiment is meant to mimic the situation in which you have a large monopolized food item." Using grooming as the favor, the researchers studied whether or not a chimp that had just been groomed was more likely to share food with the pal who had groomed him. "That would provide evidence for keeping track of who has done a favor," Jaeggi said. However, grooming releases endorphins, he added, and that general sense of wellbeing on the part of the food owner might lead to more indiscriminate food sharing.
Bonobos, on the other hand, presented a different result. While chimpanzees have a formalized dominance hierarchy, food is available to most individuals, no matter what their group status. That is not the case with bonobos. Bonobos don't establish formal hierarchies, so they don't know on an individual basis where they fit within the group. Also, they don't form coalitions as much as chimpanzees do. "The food sharing situation sort of freaked them out," said Jaeggi. "All of a sudden there's all this food that's owned by one individual, and they don't really know what to do about it. They want to get it, but they don't dare, because they don't know what the consequence will be."
Jaeggi added that bonobos did a lot more grooming, most likely because they sought the calming effects of the endorphins. "And there we did see an effect of grooming on sharing," he said. "Chimps would go and take food pretty confidently, but Bonobos were more reticent. They'd reach out and then groom. It seemed to be that they'd groom to release tension, and then there would be these short-term reciprocal exchanges."
But even those exchanges seem to be more a byproduct of the need to reduce tension, he noted, rather than short-term contingencies used to establish reciprocity.
So, what do these findings tell us about ourselves? Jaeggi suggests we should take seriously this evidence of long-term reciprocity in animals. "It's really not qualitatively different from what people do," he said. "They establish these lasting relationships, and within them, services are exchanged without the participants keeping close track of who's doing what for whom."
However, humans also have the capacity for more contingent reciprocity, which raises questions about its purpose, and how it developed. "Maybe that's something that's more culturally learned," said Jaeggi.
Andrea Estrada | EurekAlert!
Tiny songbird discovered to migrate non-stop, 1,500 miles over the Atlantic
01.04.2015 | University of Massachusetts at Amherst
The 'intraterrestrials': New viruses discovered in ocean depths
01.04.2015 | National Science Foundation
Langstreckenflugzeuge sollen künftig mit wenig Treibstoff starten und erst in 10 000 Metern Höhe vollgetankt werden. Auf diese Weise liesse sich rund 20 Prozent Kerosin einsparen. In einem europäischen Forschungsprojekt hat die ZHAW zusammen mit Partnerinstitutionen aus fünf Ländern ein solches Konzept für die Luftfahrt entwickelt.
In Sachen Energieeffizienz ist bei Flugzeugen noch viel Luft nach oben: Denn auch modernste Langstreckenflugzeuge wie der Airbus A380 oder die Boeing 787 sind...
Worst Case: Sonntagnachmittag, erste Radtour bei schönem Wetter. Ein Autofahrer rast vorbei und wirft seine PET-Getränkeflasche achtlos in den Graben. Das Material der Flasche wurde aus Rohöl hergestellt und wird einige hundert Jahre benötigen, bis es zersetzt ist. Vollständig abgebaut wird es nie, zurück bleiben winzige Teilchen das sogenannte Mikroplastik. Fraunhofer UMSICHT begegnet den kleinen Kunststoffpartikeln in zwei aktuellen Maßnahmen.
Die »Initiative Mikroplastik« möchte durch die Initiierung von Forschungs- und Entwicklungs-Vorhaben die Mengen und Sorten an Mikroplastik in der Umwelt...
Gläserne Bürobauten gehören zu den großen Energiefressern. Sie müssen aufwändig klimatisiert werden. Ein von Fraunhofer-Forschern und Designern entwickeltes Fassadenelement für Glasfronten soll den Energieverbrauch senken. Dazu nutzt es die Wärmenergie der Sonne. Ein Demonstrator ist auf der Hannover Messe zu sehen.
Fast 40 Prozent beträgt der Anteil von Gebäuden am gesamten Energieverbrauch in Deutschland. Das Heizen, Kühlen und Lüften von Wohnhäusern, Büroimmobilien und...
Spring is here and ectotherms, or animals dependent on external sources to raise their body temperature, are becoming more active. Recent studies have shown...
Herausragende chemische, thermische und tribologische Eigenschaften prädestinieren siliziuminfiltriertes Siliziumcarbid für die Produktion großvolumiger keramischer Bauteile.
Ein neuartiges Verfahren überwindet nun verfahrenstechnischen Grenzen konventioneller Formgebungsmethoden. Dadurch können Komponenten mit großen...
01.04.2015 | Veranstaltungen
01.04.2015 | Veranstaltungen
01.04.2015 | Veranstaltungen
01.04.2015 | Energie und Elektrotechnik
01.04.2015 | HANNOVER MESSE
01.04.2015 | Messenachrichten