Descartes' issues: reasoning or just machine-like?
Claws, wings, teeth, feathers, etc. are all adaptations that specialize
creatures. While primates too have specializations, they retain greater
adaptability only useful in certain circumstances, e.g. longevity, slow
maturation, high parental investment.
These have to be open, flexible, to be of maximum benefit; yet they need to be
acquired early in life for the same reasons. Hence, human primates --to a
lesser degree our close relatives -- are paradoxically specialized to be
general! That is, we have evolved brain mechanisms that enable us to "learn to
learn" specific things such as human language, which in turn enables learning
from others far more efficiently than any form of social priming.
Human culture and behavior is synonymous with tool use. The practical value of
tools --from clubs, knives, and needles to computers and science -- even
language --needs no comment.
The obvious differences between the universal use of tools by humans and their
sparse use by NHPs suggests understanding tool use may reveal much about human
nature and its origins.
One might get the impression from some recent writers that NHP use of tools was
a recent and surprising--even dismaying discovery. Savage-Rumbaugh (1995)
says, for example, "The belief that man alone can make tools had gone by the
wayside in the first years of Jane Goodall's observations in the field. p.
Despite such suggestions to the contrary, tool use in NHPs has been known at
least since Darwin. He noted, for example,:
Some of the earliest experimental work including that of Kohler and others
documented considerable tool-using capability in the laboratory, supplementing
the anecdotal observations from performing apes and early naturalistic
observations (Garner, 189x).
Recent research --Goodall's observations on chimpanzees' use of sticks in ant
fishing, detailed accounts of nut-cracking-- as well as experimental work
demonstrate and more imortantly refine both the degree and limitations of
tool-use in NHPs. This research does not radically change our conception of
the primate order--except perhaps for those who were ignorant of prior work.
The more sophisticated recent analysis, do however, raise subtle and important
questions about how individuals and social groups come to utililize tools.
We can imagine Descarte's answer to the question --only if it is a flexible
general usage with some understanding of cause-effect relationships.
Bryne says: "single, isolated cases of object manipulation give little
confidence that the perpetrators have a general understanding of cause and
effect relations among objects; a wider repertoire of tool use, showing some
flexibilty, would point more clearly to intelligent usage....for a few species
of primates....a picture of animals that can use a range of tools for a range
of purposes, animals that can choose between methods. This suggests real
These have relatively large brains and are generally thought quite intelligent
for monkeys. Bryne suggests their success stems from their great activity
rather than insight into why an object makes a useful tool. 93
Only the western chimps systematically crack nuts; this reflects availability
and possibly some natural selection at work.
Orangs are the most obvious example. They apparently can do anything chimps do
in captivity but seem to little in the wild.
The basic point here is that humans clearly can acquire knowledge from others
by observation and instruction. Apes surely benefit from the presence of
others with solutions to problems but exactly how remains unclear as
Tomasello's (1994) experiments suggest. See Bryne (1995) for a thorough
Also see Nagell, K., Olguin, R. S., & Tomasello, M. (1993). Processes of
social learning in the tool use of chimpanzees (Pan troglydytes) and human
children (Homo sapiens). Journal of Comparative Psychology, 107,
174-186. (video data)
Bryne (1995), following Tomasello (1990) distinguishes "emulation" from other
types of social priming in that the goal of the observed animal is emulated.
Tomasello (1994) compares chimps with humans on this dimension.
"I believe these studies suggest that chimpanzees and human children understand
the tool-using behavior of conspecifics in different ways. For human children,
the goal or intention of the demonstrator is a central part of what they
perceive and, thus, her actual methods of tool use--the details of the way she
is attempting to accomplish that goal become salient. For chimpanzees, the
tool, the food, and their physical relation are salient; the intentional states
of the demonstrator and her preceise methods, on the other hand, are either not
perceived or seem less relevant. p. 305"
Kohler and others, Wright (1972) in HP, 232,, and Kanzi (video) all show skills
at tools use--not to mention hundreds of imaginable circus acts and the
achievements of the home-raised chimps.
Much of this is captured in the descriptive features of the stages in Piaget's
Human tool use is not only universal; so is the culture of tool making.
This sort of feedback is only likely when there are extreme advantages to using
tools. In the rainforest environments, these advantages may not be great.
Recall how the Tai chimps devised a modest nut-cracking culture.
Indeed the unique human hand, with its opposable thumb and precision grip may
have been shaped by the increasingly important tool use of our ancestors.
Susman (1994, 1995) argues that tool use shows up in the fossil record of the
hominid hand about 2 million years ago, about 500,000 years after the earliest
stone tools have been dated.
While there are many reports of hand preference in primates, only humans as a
species consistently show a right hand preference across many tasks.
Annett (19xx, 1991) has argued handedness is a genetic trait related to
MacNeilage (19xx) argues in his "postural origins" theory that handedness has
its roots back in ancient prosimians who clung to branches with their right
hand and reached for food with the left. One implication from this theory is
that to really evaluate handedness, the animal has to be put in certain
situation for a handedness tendency to reveal itself.
Overall species, there appear to be three general tendencies. The prosimians,
like their ancestors, still display a left hand preference. whereas apes in
varying degrees and situations and of course humans , prefer their right hand.
McGrew and Merchant, 1992, for example found no handedness in termite fishing
but a right hand bias in reaching. Hopkins, Bard, Jones, and Bales, 1993 found
an interesting relationship between throwing hand, position, and sex. Captive
females were more likely to throw with the right hand in both four and two
legged positions; while males used their right side much more when bipedal.
This raises some interesting speculation about the possible interrelationship
of human lateralized function, language, and bipedality.
"Evolution could not supply an animal with mental or physiocal quipment of
which it has no need, because there can be no selection pressure if the
equipment is of no value in promoting survival. 222 HP"
Discuss the use of tools by the large primates. Describe and contrast typical
use contexts, advantages, and acquisition of these skills in the various
species. What factors play a role in tool use and the evolution of those
behaviors? What are some issues in interpreting the origin of these behaviors
in individuals (ontogeny)? For example, what distinguishes "intelligent" tool