The use of tools - taking inanimate objects and using them to solve a problem - was, until relatively recently thought of as being an exclusively human skill. But the more we observe the natural world, the more we discover about the extraordinary ways other animals have managed to survive.
Sometimes the tools are simple – for example, Galapagos finches use cactus spines to fish for insects in hollows. But some animals are very sophisticated in their tool use, taking steps to manufacture objects to improve their effectiveness.
Chimpanzees – our closest relatives – use tools with astonishing agility. They fashion twigs into “fishing tools” to extract termites where their hands cannot reach; they make “sponges” by chewing leaves and dipping them into water in tree hollows to drink; they make “hammers” and “anvils” from rocks to crack open nuts and they hurl sticks or rocks like weapons to intimidate rivals.
And, very occasionally, they have been seen hunting other primates with “spears.”
Filmmakers have captured this rare and extraordinary event for wildlife series Life Story. In the sequence above, a wild chimp in Senegal breaks off a branch and fashions the end into a sharp point, while a younger apprentice watches. The victim: a galago, or bushbaby, hiding in a hollow log. The hunter plunges the “spear” into the log and tests the end for blood. Eventually he flushes out the bushbaby and eats it.
Kelly Boyer Ontl, an anthropology PhD candidate at Iowa State University, US has studied this troop of spear hunting chimps in Fongoli, Senegal – the only population of chimps in which spear hunting with branches has been regularly observed.
She says experts are still trying to discover whether the spear-making skill is “related to learning” or “simply an adaptation to the local environment”.
“Chimpanzees use sticks as termite fishing probes, or beehive pounders, or galago hunting sticks. We’ve also seen chimpanzees use sticks to deter predators or fend off unwanted intruders… for chimpanzees, sticks and branches are multipurpose tools that, depending on the context and situation, require different modifications, techniques of use and levels of finesse or strength to operate," says Ms Boyer Ontl.
“This ability to use an object in multiple scenarios, adapting it as necessary, is a sign of intelligence in my book.”
Tool manufacturing in animals has fascinated scientists because, until the 60s, humans believed we alone were capable of making tools. The discovery that chimpanzees used sticks to extract protein-rich termites forced us to re-think.
In 2005, researchers recorded the first tool use in wild gorillas. The group of western gorillas (Gorilla gorilla) lived in a swampy forest in northern Congo. Living on the banks of a water resource also presented the troop with a particular problem: how to cross the deep pools safely.
One adult female had a solution. Researchers witnessed a gorilla they had named "Leah" using a metre-long stick as a measuring tool to test the depth of a water pool she wanted to cross. Holding the branch vertically, she stretched forward and put it into the water. Then she waded in, frequently testing the depth. The team recorded: “She then moved further into the pool, holding the detached branch in her right hand and using it as a walking stick for postural support.”
"Leah" advanced 8-10m into the pool using this technique before she appeared to change her mind and returned to her calling babies on the water edge. She then led her family around bank edge to the desired foraging spot.
The second observation of tool use in wild gorillas, recorded in the same paper, involved another adult female called “Efi” who picked up a shrub trunk and placed it on swampy ground in front of her as a bridge. “We could not see if the bridge was long enough to cross the swampy ground, but it certainly gave the female more stability underfoot and it supported her weight for at least part of the distance,” the researchers wrote.
These observations showed habitat type – and not just food – can drive tool use.
And the image of a gorilla, standing upright to use a measuring stick was a reminder of how similar these great apes are to ourselves. One of the researchers, Dr Thomas Breuer, said at the time: "What's fascinating about these observations is the similarity between what these creatures have done, and what we do in the context of crossing a pond."
It was only in recent years that scientists discovered octopuses shared the ability to use tools with well-known tool users such as great apes. The cephalopods are known for their problem-solving abilities but in 2009, the innovative use of coconut shells by veined octopuses (Amphioctopus marginatus) in Indonesia took scientists by surprise.
In the clip above, also filmed for Life Story, one of the soft-bodied creatures is seen grasping a coconut half in its arms and scuttling off to find another half. It then encloses itself in a self-made protective shell to hide from predatory cuttlefish. The coconut is even used as a getaway vehicle – the octopus inside rolling away from danger.
Parrots have demonstrated tool making behaviour in captivity which has not been seen in the wild. In 2012 a captive Goffin’s cockatoo called Figaro amazed researchers when he spontaneously bit off a piece of wood and used it as a lever to reach a cashew nut on the other side of a mesh fence. It was the first recorded example of tool use in parrots.
Perhaps surprisingly, it is another bird – the New Caledonian crow – that gives chimpanzees a run for their money as the animal kingdom's master tool users.
Corvids have demonstrated astounding intelligence in numerous studies, but New Caledonian crows are unique among crows for their sophisticated tool-using skills. They use at least four types of tools to extract food in different situations. One subtle technique is to irritate their prey with a thin stick so it bites down and is dragged out of its hiding place. And some crows develop such a fondness to a particular tool that they carry it around with them.
A tool-orientated society suggests tool design may be culturally transmitted among New Caledonian crows, learning from other members of the group how to successfully make particular designs. It can take many months for young apprentices to master these skills.
But there is no doubt that it was the behaviour of chimpanzees, our closest animal relatives, that first told us tool use was not an exclusively human talent. After all, there are only around 250,000 generations separating us.
See chimpanzees’ remarkable hunting skills in Life Story at 21:00, Thursday 7th November on BBC One.