Dumb blonde jokes don't apply to wild blonde capuchins. These clever, fair-haired monkeys have invented a new and tool-conserving method to fish for termites, researchers have just discovered.
The technique, reported in the latest Royal Society Biology Letters, has never been documented before for primates, including humans. In fact, people who recently tried out the new five-step termite fishing method found that it worked better than anything else at retrieving the nutritious, yet pesky, insects, which some human cultures eat too.
"Our observations started when the capuchins were already fishing for termites," lead author Antonio Souto told Discovery News. "Under these circumstances, we can only speculate how this behavior began."
"It is tempting to believe that a serendipitous discovery was made by one of the members of the group and then other capuchins learned how to do it through observation," added Souto, a researcher in the Department of Zoology at the Federal University of Pernambuco.
Under a grant from the National Council for Scientific and Technological Development, Souto and his colleagues studied a group of six tufted blonde capuchins in the northeastern Brazil Atlantic Forest in the state of Paraiba. This species is critically endangered and was once even thought to be extinct, until small groups like this one were rediscovered. At present, it's estimated that only around 180 of the golden-hued monkeys exist.
The monkey's diet consists of fruits, spiders, small vertebrates, an occasional sweet sip of sugar cane, and insects, including termites. The scientists noticed that three male blonde capuchins used a unique, multi-step method to extract termites from nests located high in the forest canopy, up to around 33 feet above the ground.
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With his semi-prehensile tail wrapped around a tree branch, the monkey sits in a squatting position on a limb. The individual next taps on the sides of the termite nest before breaking a branchlet off the tree. Using a rotating motion, the monkey inserts the stick into the nest. Upon retrieval, he inspects the stick and then eats the attached termites.
"When a nest is disturbed by an object breaking into its walls, soldiers (of this Brazilian termite species) swarm at the place where the break occurs," Souto explained. "Our results indicate that tapping the walls before inserting a stick increases the number of extracted termites, possibly because soldiers enter into a state of alert prior to the break, enhancing their response toward the strange object."
Tapping isn't the only secret to better termite fishing.
When the researchers tried out the insect-hunting method themselves, they determined that rotating the stick also prevented this tool from breaking. Souto believes the rotation, like a drill, causes abrasion of the nest surface material, helping to create the needed hole.
The findings add to our knowledge of how tool use evolved, and continues to evolve, in primates. Previously it was thought that our ability to walk with two feet on the ground, freeing up our hands, gave us a technological edge over other primates. Now it's known that manual dexterity can lead to successful tool use off the ground. The researchers also suspect that having a varied diet, as these blonde monkeys do, helps with tool innovations.
Elisabetta Visalberghi and Eduardo Ottoni, two other primate experts who have also studied tool use in capuchin monkeys, both told Discovery News that the new study is interesting and relevant. Ottoni, an associate professor at the University of Sao Paulo, added that he, too, has observed spontaneous use of stick tools by another population of capuchin monkeys.
Souto concluded that he hopes the forest habitat of wild blonde capuchins will be protected, to safeguard the few remaining members of this species. He also calls for genetic analysis of these monkeys, planning viable corridors for their movement in the forest, and "an aggressive campaign on environmental education," to ensure that conservation efforts are enforced and respected.
© 2012 Discovery Channel