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© clix, stock.xchngSome chimps use multi-purpose tools to forage honey from hives
If you're impressed that chimps can use tools to hunt or crack nuts, wait till you hear what they do when foraging for honey. Not only do they construct several different tools for the purpose, but they use them sequentially - an achievement approaching the abilities of early Stone Age humans.

A team led by Christophe Boesch of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, studied chimps living in Loango National Park in Gabon. They found that the chimps built and used five different types of tools to help them find beehives and extract honey: thin, straight sticks to probe the ground for buried nests; thick, blunt-ended pounders to break open beehive entrances; thinner lever-like enlargers to break down walls within the hive; collectors with frayed ends to dip honey from the opened hive and bark spoons to scoop it out. Various tools were often found near the same hive, suggesting that the chimps employ them in sequence (Journal of Human Evolution, DOI: link).

A few tools even appeared to have two uses, with enlargers at one end and collectors at the other. This is the first example of a non-human species constructing multipurpose tools.

Some of the tools would require several steps to make, so making and using the entire toolkit implies an impressive ability to plan ahead, compared with, say, cracking a nut with a stone.

Probing for underground hives also requires the chimps to conceive of the existence of unseen objects. The mental skills needed for this and the tasks that follow rival those displayed by humans in the early Stone Age, says Boesch. Indeed, he believes the desire to successfully obtain honey could have been one of the pressures that favoured increased intelligence as humans evolved.