Tool Use
What are the main drivers and constraints underlying the evolution of tool use in animals? // What can
studies of tool use tell us about animals’ understanding of the physical world? // Compare tool-related
behaviour across different species, including humans. // What can non-human tool use tell us about our
past? // What can tools of non-human animals tell us about their understanding of the physical world?
DEFINING
Defining tool use (choose your own by combining these)
GOODALL (1970): "the use of an external object as a functional extension of mouth or beak, hand or
claw, in the attainment of an immediate goal."
ALCOCK: “the manipulation of an inanimate object, not internally manufactured, with the effect of
improving the animal's efficiency in altering the form or position of some separate object."
SHUMAKER et al. (2011, pg. 10) (after BECK (1980)): "the external employment of an unattached or
manipulable attached environmental object to alter more efficiently the form, position, or condition
of another object, another organism, or the user itself when the user holds and directly
manipulates the tool during or prior to use and is responsible.”
Tools are characterised by BECK (1980) as objects that (1) are not physically part of the given animal, (2)
are not fixed in their environment (i.e. a chimp scratching itself on a tree is not tool use), and (3) are used
for a purpose beneficial to the animal. HANSELL & RUXTON (2008) note that BECK qualifies this definition
extensively, and subsequent studies using this definition do not take these qualifications into account.
Categories of tool use
1) How strong is the genetic element?
2) Facultative/obligate (do they need it to survive?)
To identify shared selective forces, it is important to define categories of tool users (otherwise the
comparative method is lumping very different things)
Construction
Most definitions (and most of the tool use field) exclude construction behaviour.
GOODALL (1970): definition excludes construction behaviours by focusing on immediate benefit
(construction tends to focus on long-term benefit).
Why aren’t construction behaviours included in studies of tool-users?
HANSELL & RUXTON (2008): Some construction behaviours are just as complex, if not more so, than tool-
use e.g. beavers are considered tool users because of the “step” they use to fell trees at a higher level up
the trunk, but this is unlikely to have more cognitive complexity than their intricately constructed dams. At
the other end of the spectrum, the Ammophila wasp is considered a tool-user because of its use of a stone
“hammer” to compress the material at the entrance of its burrow. The basis of this behaviour, however, is
likely to be genetic and deeply intrinsic, rather than demonstrative of advanced cognitive development and
intelligence.
BECK (1980) distinguishes between tool and construction behaviours for the purposes of his study, but
makes no argument to distinguish between them at the neurological/intelligence level and does not make
the argument that the two are inherently distinct behavioural entities, demonstrated by BECK’s discussion
of the numerous ‘borderline’ cases between tool and construction behaviours.
, TAXONOMIC DISTRIBUTION
OAKLEY (1949): identifies tool use as a distinctive human feature.
GOODALL (1960s): first paper to challenge the misconception that only humans use tools
Chimpanzees at Gombe use sticks to “fish” for termites
Taxonomic distribution of tool use is broad: 4 phyla (Echinodermata, Arthropoda, Mollusca, Chordata) and
10 classes (sea urchins, insects, spiders, crabs, snails, octopi, fish, reptiles, birds, mammals) but overall is a
rare trait (<0.2% of catalogued animal genera)
Sea urchins wear shells and pebbles for camouflage/ defence
Blanket octopuses carry jellyfish tentacles as defensive weapons
Marine crabs wave stinging sea-anemones in their pincers for defence
Sphecine wasps use pebbles to hammer down dirt outside burrow
Crocodiles use sticks as lures to catch avian prey
South American cichlids use leaves as tablets for carrying eggs
Archer fish spit jets of water to knock prey off perch
Egyptian vultures drop stones onto ostrich eggs to break them
Galapagos woodpecker finches use cactus spines to extract insects
Bottlenose dolphins carry sponges as foraging aids
Elephants use branches held in their trunks as fly swats
Tool use is a rare trait, documented in 0.01% of non-primate mammalian species (CHEVALIER-SKOLNIKOFF
AND LISKA 1993 cited in MANN et al. 2008), 10 primate species (≈4% of primates) (BREUER et al. 2005 cited
in MANN et al. 2008) and 30 bird species (≈0.29% of bird species) (LEFEBVRE et al. 2002 cited in MANN et
al. 2008).
In most species the number of different tool-use behaviours exhibited is 1
Exceptions appear limited to primates, birds, elephants and possibly octopi
Chimpanzees stand out: known to perform dozens of different forms of tool use across foraging,
self-maintenance, and the social/communicative domains (MCGREW 2004; WHITEN et al. 2001)
ARE TOOL USERS COGNITIVELY SPECIAL?
Cognitive ability does pose constraints on certain species’ tool use, but one must be cautious with the
conclusion that there is anything cognitively “special” about tool users.
Opposition
Experimental evidence that has not been able to demonstrate clear cognitive differences between tool-
using species and non-tool-using species.
Some cognitively “simple” animals use tools (e.g. invertebrates/insects)
E.g. Ammophila wasp stone hammer (NOTE not an invertebrate – has an exoskeleton)
In “rake tasks” that require animals to pick the correct tool in order to retrieve a reward, for example,
species that don’t typically (i.e. in their natural habitat) use tools have been observed to succeed in trials
that require an understanding of conceptual aspects of the pulling problem.
SANTOS et al. (2006): rake task experiment featuring two non-tool-users – cotton top tamarins (Saguinus
oedipus) and vervet monkeys (Cercopithecus aethiops). Found that both species were able to recognise
that effective pulling tools must be made of rigid materials
