When people think of social experiments that use animals most think of chimpanzees or gorillas, but a new study performed by Christine Drea, an evolutionary anthropologist at Duke University, used spotted hyenas. The study challenged spotted hyenas to work together to earn food rewards by tugging on two ropes simultaneously. This study showed that spotted hyenas were better at cooperating with each other than chimpanzees are.
The spotted hyenas required no training to figure out the trick of pulling the ropes together and this example shows that predators that hunt in packs may be good models for studying cooperative problem solving. This also demonstrates that hyenas work together in a lab for food and they also work together for food in the wild while they hunt. The experiment was set up in a way to mimic a natural hunt for spotted hyenas. The two ropes that dangled from a platform must be pulled extremely hard in order for the trap door to open which resembles the action of bringing down prey in the wild.
The first attempt used three pairs of captive hyenas with no training and the first pair completed the task in less than two minutes. This experiment was continued with thirteen other pairs of hyenas and all realized that synchronizing their tugs would reward them with food. After an animal become experienced with this task it would no longer attempt to tug a rope without its partner, demonstrating that the hyena realized it could not be successful alone.
Drea noted that the hyenas solved the problems mostly in silence. The hyenas used non verbal communication to synchronize their actions such as gazes and body language. Drea also noticed that pairing dominant animals together was not successful because the aggression directed towards each other was distracting to the task at hand. Drea also switched dominant and submissive partners; dominant animals switched roles with submissive ones and once the submissive animals became experienced with the experiment the animals switched back to their original roles. This observation demonstrated that spotted hyenas self adjust their behavior depending on the social context.
For the past decades researches have been interested in using primates for social experiments because of their larger brains but Drea’s study shows that social carnivores like spotted hyenas may be good at cooperative problem solving, even though their brains are much smaller in comparison to primates. This experiment has demonstrated that hyenas are better at working together towards a common goal than primates. This experiment has also shown that hyenas use non vocal communication to work together which is advantageous when hunting in the wild.
http://www.sciencedaily.com/releases/2009/09/090928131032.htm
-Sara Ku
How did they determine that the spotted hyenas were better at cooperating than chimpanzees? Did they do two experiments that were equivalent? I am just so surprised that the hyenas did better than chimpanzees. I thought that primates hunted in groups as well so I would expect them to do just as well in the cooperating experiment.
ReplyDeleteAlso, can you go more into explaining how they switched the submissive and dominant hyenas. Was it just that there was a dominant hyena and then they put in an even more dominant hyena causing the first one to be submissive?
-Tara Quist
It makes evolutionary sense that the hyenas have developed more cooperative communication skills. They are pack animals and rely on each other for survival and food. I would like to hear more about the experiments with chimp communication.
ReplyDeleteWas there any variables in the lab experiments that could have had an impact on the results? I bet some experiments could be conducted in the wild through observations, that could result in the similar results. I feel that captive hyenas would have a different relationship to food for survival. And have a different approach to cooperative communication.
-Emerson