Thursday, April 25, 2013
When you travel, do you want to drink Bellinis in Venice, and yak-butter tea in Tibet? Well, so do monkeys.
Monkeys will eat new, different food if they travel to a new place and want to fit in with the locals, according to a new study. But back home, they'll eat what Mama eats, shunning perfectly good food if it doesn't get her approval.
"When in Rome, do as the Romans do," says study co-author Andrew Whiten, director of the Centre for Social Learning and Cognitive Evolution at the University of St. Andrews in Scotland. "You're trying to ingratiate yourself." STUDY
There's growing evidence that animals learn behaviors through their social networks, much like humans, but most of those studies haven't been rigorous enough to prove that the shared behaviors don't come about through chance.
To try to nail that down, Whiten and his colleagues gave four groups of vervet monkeys living in the wild in South Africa two types of corn, one colored blue, the other red. One was flavored to be bitter. Within three months, the animals had learned to shun the bitter corn.
Then the scientists took away the corn. Months later, when a new crop of baby monkeys was old enough to eat solid food, the scientists once again put out tubs of red and blue corn. This time, none of the corn was bitter. But the baby monkeys ate only what they saw their mothers and other adults eating, even though the other corn was just as yummy.
Out of 27 baby monkeys, just one ate the non-preferred corn. And that monkey had seen his mom eat some of the shunned corn because monkeys of higher rank were hogging the good stuff. "It's really quite a strong effect," Whiten told The Salt.
The results were published in the journal Science. Most controlled experiments with animals are done in the lab, not in the wild, so this should give a better sense of how social interactions affect behavior.
The Mom effect is interesting, but not unexpected; what baby wouldn't want what Mom eats? And there's an evolutionary benefit to that, because Mom already knows what food is most nutritious or tasty, and what's to be avoided.
The second part of the monkey and corn study is more surprising.
Young male monkeys who migrated into other groups after the first part of the corn experiment almost all chose the corn eaten by the new group, even though it was the color shunned in their home group. Those 10 monkeys chose the new-crowd corn even when none of the new monkeys were watching them eat.
Just one monkey, Lekker, stuck with the corn of his home group. "He was big and strong, and immediately rose up to a high-ranking position," Whiten says. it's easy to speculate that he didn't feel the need to fit in by eating like the locals, but as Whiten cautions, that's just one monkey. "Maybe he was just a nonconformist."
There are benefits to being a nonconformist, of course; out of experimentation and innovation come great inventions. Or a nonconformist could end up eating toxic food.
The take-home, Whiten says, "is how strong social learning can be in wild animals."
It's a big week for animals, food, and social behavior. A second study in Science found that humpback whales spread new feeding techniques through their social networks -- the cetacean equivalent of sharing a new cooking method on blogs.
These scientists combed through 27 years of humpback whale observations in the Gulf of Maine. They showed that a new form of feeding, with whales slapping their tails on the surface of the water, spread among whales based on who they hung out with.
"We found it was following the social network, spreading from individual to individual, based on how much time they spent together, " says Jenny Allen, a researcher at the University of St. Andrews and lead author of the study.
The method, called lobtail feeding, was first observed in the wild around 1980. Now about one-third of humpbacks in the Gulf of Maine use it. The whales who feed that way don't seem any healthier, Allen says, which suggests it doesn't necessarily catch more fish. "It seems almost to be personal preference."
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