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Animal behavior

Bumps on the road of evolution

An USP study knocks down a model on the use and making of tools

The reconstruction of the path of the emergence of tools use and manufacture in human evolution gained an unexpected obstacle. Through the observation of the capuchin monkey (Cebus apella), researchers at the Biosciences Institute of São Paulo University (USP) have shot down a model built some years ago, according to which the monkeys paved the way which later would be followed by human beings.

Besides man, only the capuchin monkey, the chimpanzee (Pan troglodytes), the orangutan (Pongo pygmaeus) and the gorilla (Gorilla gorilla) are capable of using stones and sticks as tools, to break coconuts and nuts, for example. If trained, the four of them can carry this out in captivity, but only the first two are naturally capable of repeating the deed in their own habitat, according to the reports of some researchers. It was this fact that transformed the capuchin monkey into a possible model to understand how mankind began to use hatchets, hammers, spears and other instruments.

The work of the researchers Euphly Jalles-Filho, Rogério Grassetto Teixeira da Cunha and Rodolfo Aureliano Salm, published in the Journal of Human Evolution (May edition), shows that such a model, until that moment widely accepted, is not true. They have shown that the capuchin monkeys don’t have the ability to take their tools with them as they move from place to place as did the Homo abilis 2.6 million years ago, the first species of the human race to be associated with stone slivers used as tools.

“Research in Ethiopia, Tanzania and in Kenya indicate that the Homo abilis walked over wide areas carrying his own tools and that this characteristic the capuchin monkey does not have.” explains Jalles. In these regions, stone slivers used as tools that originated form other places have been found. The reassembling done by the researchers makes it clear that they were from different areas, that is, they were transported by the Homo abilis.

“The concrete evidence of the manufacture and use of tools was the fact that they were carried with the primitive humans and this fact probably had an influence in the evolution of their use.” Subsequently, the model imagined until now fails to capture the crucial aspect of the question: the establishment of ample transport networks of the tools and the material for their production. Thus, the behavior among the capuchin monkeys doesn’t show a functional and formal analogy with the technological behavior of the first primitive human beings.

The object of the study to help to understand evolution, the capuchin monkey, was chosen as it is considered to be the one of the most intelligent species of the Americas, and also for its recognized ability. Curious, badly behaved and at the maximum a half a meter tall, they are being studied more and more by Brazilian, North American and European researchers, even as an option for comparative work with chimpanzees, natives of Africa. In South America, the capuchin monkey is found in Colombia and Argentine, and in Brazil in environments as varied as the Amazon, the Cerrado (wooded savanna), the caatinga (dry land) and the Atlantic Rain Forest.