Monkeys may have helped our species become civilised by teaching cavemen one important trick
Academic suggests wise apes may have inspired progress of humankind
Humans may have learned to use tools by watching MONKEYS, researchers have suggested.
The study shows that monkeys have been using stone tools to crack open cashew nuts for hundreds of years at least.
Researchers say that early human behaviour may even have been influenced by their observations of monkeys using such tools.
New archaeological evidence suggests that Brazilian capuchins have been using stone tools to crack open cashew nuts for at least 700 years.
If true, this means the diggers have discovered the earliest archaeological examples of monkey tool use outside of Africa.
Controversially, the academics said their discovery should prompt other anthropologists to look at whether early human behaviour was influenced by their observations of monkeys using stones as tools.
The research was led by Oxford University's Dr Michael Haslam, who has previously presented archaeological evidence showing that wild macaques in coastal Thailand used stone tools for decades to open shellfish and nuts.
The new study involved researchers from Oxford and the University of Sao Paulo in Brazil, who watched groups of capuchins at Serra da Capivara National Park.
The researchers saw wild capuchins use stones as hand-held hammers and anvils to pound open hard foods such as seeds and cashew nuts, with young monkeys learning from older ones how to do the same.
The capuchins created what the researchers describe as 'recognisable cashew processing sites' - leaving stone tools in piles at specific places such as the base of cashew trees or on tree branches after use.
They found that capuchins picked their favourite tools from stones lying around, selecting those most suitable for the task.
Stones used as anvils were more than four times heavier than hammer stones, and hammers four times heavier than average natural stones.
The capuchins also chose particular materials, using smooth, hard quartzite stones as hammers, while flat sandstones became anvils.
Using archaeological methods, the researchers excavated a total of 69 stones to see if this tool technology had developed at all over time.
Through mass spectrometry, the researchers were able to confirm that dark-coloured residues on the tools were specifically from cashew nuts.
They also carbon dated small pieces of charcoal discovered with the stones to establish the oldest were least 600 to 700-years-old - meaning the tools predate the arrival of Europeans in the New World.
The researchers estimate that around 100 generations of capuchins have used this tradition of stone tools.
They compared tools used by modern capuchins with the oldest excavated examples, finding they are similar in terms of weight and materials chosen.
The researchers said the apparent lack of change over hundreds of years suggests monkeys are 'conservative' - preferring not to change the technology used, unlike humans living in the same region.
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Dr Haslam said: "Until now, the only archaeological record of pre-modern, non-human animal tool use comes from a study of three chimpanzee sites in Cote d'Ivoire in Africa, where tools were dated to between 4,300 and 1,300 years old.
"Here, we have new evidence that suggests monkeys and other primates out of Africa were also using tools for hundreds, possibly thousands of years.
"This is an exciting, unexplored area of scientific study that may even tell us about the possible influence of monkeys' tool use on human behaviour.
"For example, cashew nuts are native to this area of Brazil, and it is possible that the first humans to arrive here learned about this unknown food through watching the monkeys and their primate cashew-processing industry."
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