Trade is fundamental to our way of life but may not be unique to us, says Leona Williams.
There is evidence to suggest that our closest animal relatives - monkeys and apes - also exchange valuable commodities: for example, grooming for alliance, or sex for food. In experiments, several primate species have also successfully used tokens to request food. Laboratory settings can only reveal so much, however.
- "They are one of the few animal species who gift for reasons that don’t involve sex." Discover 10 animals that like to give gifts
- Can any other great apes - other than humans that is - keep secrets?
A study of Balinese long-tailed macaques provides compelling evidence of spontaneously arising trade in wild animals.
These monkeys steal valuable, but inedible, items from humans (mobile phones, glasses, cameras) only returning them in exchange for food.
The monkeys also seem to grasp that some items are worth more, holding onto the most valuable steals until presented with the very best foodstuffs - maximising their payoff.
This may be the first known example of such an economic system in wild animals and could help us understand the origins of our own monetary systems.
Top image: Balinese long-tailed macaques © Getty
