Monkeys Can Make Stone Tools, but They Don’t Use Them

Oct 24, 2016

By James Gorman

The capuchin monkeys of Serra da Capivara National Park in Brazil are well known for using rocks. They use them as hammers to crack open nuts. They use them for digging. They even use them to show off to potential mates. Now scientists report that they also spend time banging stones together, for no clear reason, producing sharp-edged stone flakes that are just like some of the first tools of early humans.

They don’t use these flakes, so they are clearly not trying to produce them. The findings don’t challenge the record of human evolution in Africa, researchers say, in which such tools are found in a context that makes clear they were produced by hominids. But the flakes do show that neither the human hand nor brain is necessary for making such artifacts.

Tomos Proffitt, a researcher at Oxford who has studied early human tools produced in Africa, and his colleagues in England and Brazil, reported the observations and an analysis of the rock flakes in the scientific journal, Nature.


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11 comments on “Monkeys Can Make Stone Tools, but They Don’t Use Them

  • But the flakes do show that neither the human hand nor brain is necessary for making such artifacts.

    Artifact – an object made by a human being, typically an item of cultural or historical interest.

    Here we go again. Are we redefining the word, or do we simply dismiss (or reject) this as the improper use of a word that is clearly defined as applying only to human-made objects?

    …what level of intelligence and physical skill was needed for the very first stone tool production technology to emerge.

    I think this observation suggests that stone tool “production” by humans was most likely a similar “happy accident”, and the key to benefiting from the accident is the ability to see the utility of the accidental product and then converting the accident into an intentional action.



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  • @Op – The capuchin monkeys of Serra da Capivara National Park in Brazil are well known for using rocks. They use them as hammers to crack open nuts. They use them for digging. They even use them to show off to potential mates.
    Now scientists report that they also spend time banging stones together, for no clear reason, producing sharp-edged stone flakes that are just like some of the first tools of early humans.

    As I recall, inexperienced capuchins select unsuitable stones to use as hammers on nuts, and these break when they try to use them.

    This may well produce sharp flakes for which they have no use.

    More experienced monkeys select and retain effective durable stone tools, transport them to different anvil sites, and occasionally lend them to friends.

    https://www.researchgate.net/publication/236863821_Use_of_stone_hammer_tools_and_anvils_by_bearded_capuchin_monkeys_over_time_and_space_Construction_of_an_archeological_record_of_tool_use

    Wild bearded capuchins (Sapajus libidinosus) in the cerrado (seasonally dry savannah-like region) of Brazil routinely crack open several species of palm nuts and other hard encased fruits and seeds on level surfaces (anvils) using stones as hammers. At our field site, their nut cracking activity leaves enduring diagnostic physical remains: distinctive shallow depressions (pits) on the surface of the anvil, and cracked shells and stone hammer(s) on or next to the anvil. A monthly survey of the physical remains of percussive tool use at 58 anvils in our study site over a 36-month period revealed repeated use, seasonal consistency, temporal variation, landscape-scale patterning, appearance of new hammers and transport of existing hammers to new anvil sites. Artefactual evidence of the temporal and spatial pattern of tool use collected in the survey is in correspondence with concurrent direct observation of monkeys using and transporting tools at this site. Shell fragments endure for years above ground, suggesting that they may also endure in the strata around anvil sites. The bearded capuchins provide an opportunity to study the construction of percussive tool sites suitable for archeological investigation concurrently with the behavior responsible for the construction of these sites. We suggest several lines of inquiry into tool sites created by capuchin monkeys that may be useful to interpret the archeological evidence of percussive tool use in early humans. Archeologists should be aware that transported stone materials and artificial durable landscape features may be the result of activity by non-human animals.



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  • PeacePecan #1
    Oct 24, 2016 at 6:41 am

    Artifact – an object made by a human being, typically an item of cultural or historical interest.

    Here we go again. Are we redefining the word, or do we simply dismiss (or reject) this as the improper use of a word that is clearly defined as applying only to human-made objects?

    I think an up-to-date definition of “manufactured objects”, is required, without repeating the antiquated concept used by linguists, who seem unaware of the inadequacies of their presumption of manufacturing being an exclusively human prerogative, in the definition they are quoting in dictionaries.

    Tools and structures, are produced and used by numerous species of animal.



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  • Even using the word “manufactured” carries linguistic risks in this context, as it originally meant “made by hand” (from Latin manu factum), presumably the human kind. This may be tolerable when referring to primates, who (I think) definitely have hands (though clearly not human), but could be a bit nonsensical when used to describe objects produced by animals with no hands (unless we’re going to redefine “hand”, that is). But the literal “by hand” meaning of manufactured has long since been rendered obsolete by the invention of machines anyway, so why not let it expand to other species as well. As long as we all understand each other, there’s no basis for complaining.

    All facetiousness aside (and with the understanding that it’s already a lost cause), I’d sooner coin a new term than re-define an existing one that already has (had) a clear and useful meaning (until it was eroded by misuse). What you call a “presumption of… human prerogative” on the part of linguists I see as an insistence on preserving and defending the original intent of the word to describe a human activity and its products. Linguists aren’t denying that other animals can make things if/when they object to misuse of the word. If you need a word that means made by non-human (insert body part here), then make one up, but don’t commandeer one that already means something similar but clearly different. (I know it’s unrealistic, but that doesn’t mean it’s wrong.)

    And, by the way, it is because we are so quick to (irresponsibly) redefine and add new meanings to existing words that we so often have trouble understanding each other.



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  • PeacePecan #4
    Oct 24, 2016 at 8:26 pm

    But the literal “by hand” meaning of manufactured has long since been rendered obsolete by the invention of machines anyway, so why not let it expand to other species as well.

    As you say, language and meaning s evolve along with the processes and technologies they describe.

    Stone age “manufacture” of artefacts may have been originally fairly exclusively by the use of hands, but even then sinues, fibres, etc. were processed by also using teeth – so the word acquired new added meaning as tools and machines became involved.

    Slavishly sticking to a single narrow definition, simply makes no sense, but new, alternative, and additional definitions, need to be listed to preserve clarity.
    Words are merely labels, so it is unlikely that a full description is going to be included on a label!



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  • Alan4: “As you say, language and meaning s evolve along with the processes and technologies they describe.
    Stone age “manufacture” of artefacts may have been originally fairly exclusively by the use of hands, but even then sinues, fibres, etc. were processed by also using teeth – so the word acquired new added meaning as tools and machines became involved.
    Slavishly sticking to a single narrow definition, simply makes no sense, but new, alternative, and additional definitions, need to be listed to preserve clarity.
    Words are merely labels, so it is unlikely that a full description is going to be included on a label
    !”

    Excellent comment. I wonder if we human observers are not ourselves using primitive linguistic tools to describe animal “tool making” behavior.” The meme that animals make/use tools “just like us” became indelibly planted in human language after the observations of Jane Goodall and many colleagues took on a kind of authority we should examine more closely.

    Animals have considerable cognitive powers coupled with anatomical-sensory capacities to manipulate objects in their environment. Otters, for example, dive down to catch shellfish and also seize rocks from the shallow ocean floor. Upon surfacing they float on their backs placing the rock on their upward facing chest. They proceed to smash the shellfish against the rock to crack open and devour the delicacy. How does this behavior differ from watching a monkey or ape using a rock “like a hammer.” Non-human primates are anatomically equipped with grasping hands that can carry objects some distance like our pre-human hominid ancestors. Scientists speculate that either this ability and practice facilitated the growth of the hominid-to- human brain or conversely the growth of the hominid-to- human brain informed the subsequent ability and practice.

    Monkeys and apes are not hominids ( current definitions may include gorillas, chimps and orangutans more by way of “honorable mention:” (…any of a family (Hominidae) of erect bipedal primate mammals that includes recent humans together with extinct ancestral and related forms and in some recent classifications the gorilla, chimpanzee, and orangutan [Merriam-Webster online dictionary]) and though closely related on the evolutionary tree with human primates are not themselves human. At present we cannot know what we are observing in “tool-making behavior” as it “fits” into a human evolutionary story apart from recognizing that non-human animals have cognitive powers that can manipulate “found” objects for purposeful behavior at very rudimentary if remarkable levels.



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  • Melvin #6
    Oct 25, 2016 at 1:13 pm

    Monkeys and apes are not hominids ( current definitions may include gorillas, chimps and orangutans more by way of “honorable mention:” (…any of a family (Hominidae) of erect bipedal primate mammals that includes recent humans together with extinct ancestral and related forms and in some recent classifications the gorilla, chimpanzee, and orangutan [Merriam-Webster online dictionary]) and though closely related on the evolutionary tree with human primates are not themselves human.

    These are just semantic definitions from linguists.

    In terms of scientific classification, there is a strong case for humans to be included in the genus Pan – along with chimps and bonobos.



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  • Melvin #6
    Oct 25, 2016 at 1:13 pm

    At present we cannot know what we are observing in “tool-making behavior” as it “fits” into a human evolutionary story apart from recognizing that non-human animals have cognitive powers that can manipulate “found” objects for purposeful behavior at very rudimentary if remarkable levels.

    I think the recorded activities from the wild give clear parallels.

    http://discovermagazine.com/1995/nov/toolingthroughth593

    Toolmaking was once considered a hallmark of the unique intelligence of human beings. Researchers began to question that notion, however, as they discovered that wild chimpanzees, our closest relatives, use a number of tools, including sticks to get termites out of nests, and stones to crack open nuts. Moreover, they don’t just use whatever happens to be lying around–they tailor their tools to fit a particular job.

    They quickly discovered that the Suaq orangutans used tools for a number of purposes. As Ibrahim had seen, sometimes an ape will break off a branch about a foot long, snap off the twigs, fray one end, and put the other end in its mouth. Holding on to a tree trunk with its arms and legs, the orangutan rams the stick into a hole containing a termite nest. It then flicks out the broken-up chunks– full of delectable larvae and pupae–and eats them. The Suaq orangutans also use sticks to scare out ants from tree colonies. But the most common use is when they go for honey, says van Schaik. They put a stick in and poke through some nest wall and move it around and catch the honey, pull it out, turn it around and stick the other end in their mouth, and then go back in. If the stick is too long to use comfortably, they snap off one end.

    Orangutans also use tools to eat fruit. When the fruit of the Neesia tree ripens, its hard, ridged husk softens until it falls open. Inside are seeds that the orangutans love, but they are surrounded by fiberglass-like hairs that, as van Schaik can personally attest, hurt like hell. A Neesia-eating orangutan will select a five-inch stick, strip off its bark, and then carefully collect the hairs with it. Once the fruit is safe, the ape pops the seeds out with the stick or with its fingers.

    Every adult orangutan van Schaik’s team has followed for more than five minutes at Suaq uses tools. It’s clearly a routine thing, a population-wide, year-round phenomenon, says van Schaik. It’s not the idiosyncrasy of one genius.

    It’s possible, of course, that the very first invention of tools among orangutans happened relatively recently in Suaq. Van Schaik thinks that’s unlikely. Of the four types of great apes, he points out, three– chimps, orangs, and humans–have now been observed to use tools in the wild. The simplest explanation, says van Schaik, is that the apes’ common ancestor did, too.

    Van Schaik’s observations complement a growing body of research that suggests the real quantum leap of intelligence did not happen 6 million years ago among the earliest hominids but 16 million years ago among the earliest great apes. It was then, in this view, that animals first evolved insight–an ability to make connections between concepts, recognize cause and effect, and plan actions. The sort of thinking required for using tools, for symbolic communication, for empathy–for all these supposedly quintessentially human gifts–may be far older than we imagined.



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  • Alan4: In terms of scientific classification, there is a strong case for humans to be included in the genus Pan – along with chimps and bonobos.

    Of course humans and anthropoid apes are related species. If we take the term “hominid” to refer to: erect bipedal primate mammals that includes recent humans together with extinct ancestral and related forms then apes are a poor functional match for humans and their pre-human ancestors. Ape hind legs are bent like a dog’s making bipedal mobility awkward and limited. Chimps and gorillas for anatomical reasons usually walk on all fours. The straight long skeletal structure of the human leg makes long-distance migration, foraging and hauling an easy adaptation whereas ape troops usually stay close to home territories, vegetation feeding and arboreal habitats.

    “Tool making” distinguished from “tool use” still brings up invidious distinctions between shellfish-cracking stones for otters and nut-cracking stones for monkeys and apes. A dexterous creature like a chimp will unsurprisingly hit on grasping a branch and sticking it in a termite hole to extract tidbits. More remarkably, adolescent and female chimps have been observed on occasion to fashion a “spear,” from a thin branch, stripping it of leaves, sharpening the tip with their teeth and ramming it into hollow branches to kill small primates called bushbabies for their meat.

    These behaviors do not constitute “tool making” in an unambiguous human sense. The activity reflects more the animal’s limited cognitive ability combined with anatomical functioning rather than the systematic development of external materials to accomplish complex tasks. The practice of discovery, invention, modification and expanded utility stops before the implement rises to what we humans usually infer by “tool-making.”



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