(PLoS Biology)
For the second time in three days, scientists have revealed a photographic first to the world.
On Wednesday, a picture of a giant squid taken by two Japanese researchers made front pages worldwide. The creature, best known as the aquatic aggressor to Captain Nemo's Nautilus in Jules Verne's 20,000 Leagues Under the Sea, had never been observed in its natural habitat.
Visual evidence that gorillas use tools in the wild was similarly elusive, though many of us have happened upon the large primate throwing sticks or eating with a make-shift utensil at our local zoo.
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Today, in the journal PLoS Biology, the Wildlife Conservation Society (WCS), the New York-based wildlife-preservation group that operates the Bronx Zoo, released photos of two gorillas utilizing sticks to help in their activities in the rain forests of the northern Congo. "This is a truly astounding discovery," says the WCS's Thomas Breuer, whose group has been researching animals in the Congo for over 20 years.
In October 2004, Leah, an adult female whose group has been under observation since 2005, used a one-meter long tree branch to test the water depth in a small pool. She eventually waded out to the middle while leaning on the branch for support, before returning to tend to her young.
Over a month later, Efi, another female, whose group has been monitored since 2000, used a small tree trunk as a staff when she leaned into marshy water to forage for food. Once she had eaten, she turned the same trunk into a bridge, using it to crawl over a large puddle.
(PLoS Biology)
Prior to Leah and Efi, only wild chimpanzees, orangutans and, most recently, bonobos have been found wielding an implement, typically for feeding. Jane Goodall first described chimpanzee tool use over 40 years ago. Bonobos' tool use was documented in 2003. Researchers speculate that wild gorillas aren't as dependent on tools because they are strong enough to get to food sources that chimpanzees and other great apes needed help to access.
"Tool usage in wild apes provides us with valuable insights into the evolution of our own species and the abilities of other species," said Breuer about the implications of the sightings. "[These protected areas] hold the key to comparing our own development as a species with our next of kin."