Thursday, April 25, 2013 2:12 pm
It really is monkey-see, monkey-do, research shows
By SETH BORENSTEINAP Science Writer
South African monkeys switched foods purely because of peer pressure and humpback whales off the coast of New England copied a new way to round up a fish meal, according to two studies in Thursday's journal Science.
"We're not as unique as we would like to think," said monkey study lead author Erica van de Waal, of the University of St. Andrews in Scotland. "We can find many of the roots of our behaviors in animals."
For her study, 109 vervet monkeys living in groups in the wild were given a choice of food tinted pink or blue by the researchers. One color for each group was tainted with aloe to give it a harmless yucky flavor. After a few meals, the food was no longer tainted, but the monkeys still wouldn't eat the color they figured was bad.
But that changed when some of them tried to fit in with a new group of monkeys. Blue-food eaters instantly switch when they moved to an area full of pink-food eaters, even though they shunned pink food before. Pink eaters also changed when they moved to a blue-food area.
The social pressure may be like "teenagers with a desperate need to be just like the other guys," said co-author Andrew Whiten, also of St. Andrews. Or it could be that the monkeys are learning to adapt to local custom - think restaurant reviews or the old saying "when in Rome, do as the Romans do," he said.
The researchers were surprised by the finding: They were only aiming to find out if mothers taught their young the same color food preference they learned, Whiten said. The next generation automatically ate the same as their mother, showing how food choice is learned.
Just by sheer luck, some blue-eating monkeys went to the pink-eating tribes and some pink-eating males went to blue tribes. And that's when the researchers saw peer pressure in action
Of the 10 migrating males, nine instantly ate what everyone else ate. The only hold out was an alpha male, who stuck to his previous diet.
Van de Waal said it could be the eat-what-locals-eat idea, but she favors the social conformity, peer pressure concept. She figures the other males were trying to get in good with females, while the dominant male acted as "if he's already in charge, why does he need to do like the others."
In the 27-year whale study, scientists began tracking an unusual feeding behavior in 1980. Until then, whales usually fed by blowing bubbles underwater to corral small fish, which don't seem to like to swim through bubbles. Then the whales would lunge upwards and feast.
But in 1980, researchers saw one whale first smack the water loudly with its tail - a maneuver called lobtail - making a big noise and giant splash before blowing bubbles, said researcher Jenny Allen, who used to be at St. Andrews.
The number of whales doing that maneuver has climbed steadily, and is now at 37 percent, she said. This new trick coincided with a dramatic drop in the number of herring, which the whales like to eat. Allen said the technique - which might bring fish closer to the surface - seemed to be passed down through the generations.
This definitely appears to be something that is learned by copying more successful whales, she said.
Lori Marino of Emory University, who wasn't part of either study, praised the works, saying it fits with other studies showing how many animals learn socially and how strong conformity is.
Seth Borenstein can be followed at http://twitter.com/borenbears