April Flowers for redOrbit.com – Your Universe Online
Researchers have long known that fruit-eating animals use spatial memory to relocate fruit. What they haven’t known is how these animals located the fruit in the first place. A new study from the Max Planck Institute for Evolutionary Anthropology (MPG) demonstrates that chimpanzees use botanical knowledge in their daily search for food.
The research team studied chimpanzees in the Taï National Park in Côte d´Ivoire, West Africa, to discover what strategies the animals use in order to find fruit in the rainforest. The researchers conducted observations of the chimpanzees inspecting the crowns of fruit trees for available food, focusing their analysis on recordings of the animals making “mistakes” by inspecting empty trees. They wanted to know if the chimps understood that if one tree of a species is carrying fruit, they could expect to find fruit in the crowns of other trees of the same species as well. What they discovered is that the chimps do know that trees of a certain species produce fruit simultaneously.
The researchers were able to exclude sensory cues of fruit triggering the tree inspection by analyzing the “mistakes.” They found that the chimps expected to find the fruit days before feeding on it. The chimps expectations significantly increased after tasting the first fruit of the season, as well.
“They did not simply develop a ℠taste´ for specific fruit on which they had fed frequently”, says Karline Janmaat. “Instead, inspection probability was predicted by a particular botanical feature – the level of synchrony in fruit production of the species of encountered trees.”
The study found that the chimpanzees know that trees of a particular species produce fruit simultaneously and that they use this information in their daily hunt for food. Their botanical knowledge, based on the success rate of fruit discovery, is combined with an ability to categorize fruits into distinct species, which allows the animals to create expectations of finding particular fruits at the correct seasonal times.
“Our results provide new insights into the variety of food-finding strategies employed by our close relatives, the chimpanzees, and may well elucidate the evolutionary origins of categorization abilities and abstract thinking in humans”, says Prof. Christophe Boesch, director of the Max Planck Institute for Evolutionary Anthropology´s Department of Primatology.
Taï National Park is one of the last remaining remnants of the primary tropical rainforest of West Africa, and hosts many endangered plant and animal species. It is a UNESCO World Heritage Site with a chimpanzee population of 2,000-2,800 individuals, making it a prime research site for primatologists.
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