Benefits of Social Grooming in Wild Chimpanzees: Hormone Oxytocin Facilitates Cooperation

Jan. 23, 2013 — Animals which maintain cooperative relationships show gains in longevity and offspring survival. However, little is known about the cognitive or hormonal mechanisms involved in cooperation. Researchers of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, have now found that cooperative relationships are facilitated by an endocrinological mechanism involving the hormone oxytocin, even when these are between non-kin.


They collected urine samples of 33 chimpanzees from Budongo Forest, Uganda, and measured their urinary oxytocin levels after single episodes of a specific cooperative behavior, mutual grooming. The result: Oxytocin levels were higher after grooming with cooperation partners compared with non-cooperation partners or after no grooming, regardless of genetic relatedness or sexual interest. This suggests that in chimpanzees oxytocin, which acts directly on neural reward and social memory systems, plays a key role maintaining social relations beyond genetic ties and in keeping track of social interactions with multiple individuals over time.

In non-human primates and other social animals strong and enduring social bonds are typically seen between genetically related individuals but also, occasionally, between non-kin, same-sex individuals. Although such relationships are typically defined by high rates of cooperative behaviors, how they are maintained over time is still unclear. In humans and other social mammals the neuropeptide hormone oxytocin plays a central role in facilitating bonding between kin and mating partners. Catherine Crockford, Roman Wittig and colleagues of the Max Planck Institute for Evolutionary Anthropology have now analyzed the role of this hormone in the social relationships between wild chimpanzees.

To this end the researchers observed social interactions – like mutual grooming – in a group of wild chimpanzees from Budongo Forest in Uganda and non-invasively collected urine samples of the 33 female and male adult group members on plastic bags or leaves. They determined the level of the hormone oxytocin before and shortly after the animals had been grooming with each other and found that oxytocin levels were especially high in chimpanzees who had been grooming with a “bond partner”,  a cooperation partner, irrespective of whether this bond partner happened to be their kin or not. On the other hand, the level of urinary oxytocin was much lower in chimpanzees who had been grooming with a “non-bond partner”, with whom they did not share a cooperative relationship, or in animals who had not been grooming at all. Furthermore, the researchers found that the animal’s sex or age, grooming duration and other factors did not have a significant influence on urinary oxytocin levels.

“Our results demonstrate that a rise in oxytocin was dependent upon the combined effects of social grooming with a bond partner”, says Catherine Crockford of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. “Crucially, oxytocin levels were similarly high after grooming with non-kin and kin bond partners. This suggests that, in chimpanzees, oxytocin plays a key role in maintaining social relations beyond immediate genetic ties”.

“This is the first study that measures the levels of the hormone oxytocin on wild animals in a non-invasive way”, says Roman Wittig of the Max Planck Institute for Evolutionary Anthropology. “We have developed a tool with which cross-species comparisons that link underlying physiology and behavior can eventually be made of social mammals in their natural environment”. In future field research this tool will be used to compare single behaviors – like other cooperative  or aggressive behaviors–by measuring how they differ from each other hormonally.

 

Story Source:

The above story is reprinted from materials provided byMax-Planck-Gesellschaft.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.


Journal Reference:

  1. C. Crockford, R. M. Wittig, K. Langergraber, T. E. Ziegler, K. Zuberbuhler, T. Deschner. Urinary oxytocin and social bonding in related and unrelated wild chimpanzees.Proceedings of the Royal Society B: Biological Sciences, 2013; 280 (1755): 20122765 DOI: 10.1098/rspb.2012.2765
Max-Planck-Gesellschaft (2013, January 23). Benefits of social grooming in wild chimpanzees: Hormone oxytocin facilitates cooperation. ScienceDaily. Retrieved January 28, 2013, from http://www.sciencedaily.com/releases/2013/01/130123094251.htm

Mindreading Hormone? A Better Judge of Character With Nasal Spray?

ScienceDaily (July 30, 2012) — Ingesting the hormone oxytocin via nasal spray improves the ability to read people’s facial expressions. These findings hold great promise for treatment of mental health disorders and drug addiction.

An instrument was used to measure dilation of the pupils and how test subjects focused their gaze while solving tasks on a computer screen in front of them. (Credit: Olga Chelnokova)


In other contexts, oxytocin is already well-known as the “bliss hormone.” The hormone is secreted upon stimulation by touch and is known to result in a feeling of calm and physical relaxation. It is also used to induce labour in childbirth and as an aid for women experiencing difficulties in breastfeeding.

Oxytocin has also been referred to as a “mindreading” hormone. Recent research findings show that there may be some truth to these claims — although the mindreading component may have a more down-to-earth explanation.

Angry people seemed angrier

As part of a research project carried out by Siri Leknes, a research fellow at the Department of Psychology at the University of Oslo, 40 healthy students were administered nasal spray containing a dose of either saltwater or oxytocin. They were subsequently shown photographs of faces displaying angry, happy or neutral expressions. Some of the photos showed individuals displaying more “hidden” emotional expressions which tend to be picked up at a more subconscious level.

“We found that oxytocin intensified test subjects’ awareness of the emotions present in the photos. Faces expressing anger stood out as angrier and less happy, and correspondingly, faces expressing happiness were happier,” explains Dr Leknes.

“We know that people express feelings in other ways than through facial expression alone, for example, by means of body language and vocalisation. We presume that our findings also apply for these modes of expression,” she adds.

The study receives funding under the Research Council of Norway’s Alcohol and Drug Research Programme (RUSMIDDEL).

Greatest effect on those who need it the most

There were two rounds to the experiment to ensure that all student subjects were tested using both salt water and oxytocin — without letting them know which dose they would be receiving each time.

“It turns out that those with the lowest aptitude for judging emotional expression properly — that is, those with the poorest scores during the saltwater round — were the ones who showed the greatest improvement using oxytocin. This is really fascinating; the people who need it the most are thus the ones who get the most out of using the hormone,” Dr Leknes points out.

Based on previous research along with her own findings, Dr Leknes believes in oxytocin’s potential as a supplementary treatment for people suffering from mental health disorders or drug-dependency. In fact, nearly all mental health disorders involve a diminished ability to recognise the feelings of others. The same applies for drug abusers.

“Oxytocin will not be a cure-all for mental illness or drug addiction, but it may be of use as a supplementary treatment. It may make individuals better equipped to interpret the signals of others around them, which may improve how they function in social settings,” Dr Leknes explains.

Testing for treatment of drug abuse up next

Oxytocin nasal spray is available via prescription and is relatively safe when used as directed. Side effects are extremely rare. According to Dr Leknes, doctors are already allowed to prescribe oxytocin for the treatment of various problems associated with social functionality such as autism.

“In such cases, however, it’s a matter of isolated treatments which are not evaluated as a whole. It is important that we research this to gain greater insight into the effect,” she points out.

Siri Leknes and her colleagues are now hoping to take their efforts a step further and examine how well oxytocin works as a supplementary treatment for drug abusers.

“If it turns out that our assumptions are correct, then we may be able to come up with a simple treatment that would mean a great deal for people who find it difficult to pick up on the social cues of their peers,” says Dr Leknes.

 

Link:

http://www.forskningsradet.no/en/Newsarticle/A_better_judge_of_character_with_nasal_spray/1253978889915/p1177315753918

Citation:

The Research Council of Norway (2012, July 30). Mindreading hormone? A better judge of character with nasal spray?. ScienceDaily. Retrieved July 31, 2012, from http://www.sciencedaily.com­ /releases/2012/07/120730094909.htm