[Paleopsych] SW: On Advanced Ape Technology

Premise Checker checker at panix.com
Sun May 22 22:08:53 UTC 2005

Animal Behavior: On Advanced Ape Technology

[A tremendous trove here. Thanks for Eugen for forwarding Science Week's 
digest, though I don't recall looking at it before. I'm going into their 
archive, too. Lots of goodies, indeed! And the articles are short.]

    The following points are made by W.C. McGrew (Current Biology 2004
    1) The use of tools by animals to solve natural problems, especially
    in foraging, is well-known natural history [1]. The manufacture of
    tools, rather than merely using found objects, is far less common,
    being restricted to great apes and a few bird species [2]. Only
    chimpanzees and orangutans have tool-kits, that is, repertoires of
    different tool-types, that vary across populations [3-5]. Now comes
    the first report [6] of customary use of tool-sets -- two or more
    different types of tool used in sequence to achieve a single goal --
    by a community of wild chimpanzees (Pan troglodytes) in the Congo
    Basin. The finding emerged from the innovative use of modern
    technology in field primatology: "spy-cams" to monitor shy apes in the
    2) Non-human use of objects as tools is widespread: woodpecker finches
    prise out grubs with twigs, sea otters crack molluscs on stones,
    digger wasps tamp down burrow entrances with pebbles [1]. These
    animals, however, are "one-shot wonders", that is, each species is
    good at only one type of tool-use, and the objects are collected,
    used, and discarded on the spot, unaltered. Such simple acts require
    no inventiveness, being behavioral adaptations to fit certain task
    3) The fabrication of objects by transforming raw materials into
    instruments is a cognitive step forward, in that reshaping an item by
    reduction, combination, extension, and so on renders it more efficient
    [2]. Such elementary technology must be learned from others who are
    more proficient than the novice. Social learning probably underlies
    the making of palm leaf probes by New Caledonian crows, who use the
    resulting hooked instrument to extract insect larvae. Wild chimpanzees
    use twig, vine, bark, stem, or leaf-stalk probes to fish out ants,
    termites or honey from their arboreal or terrestrial cavities. Such
    flexible probes are clipped, peeled, stripped, split, etc. to the
    necessary specifications to do the job. Goodall first described this
    40 years ago in the case of termite fishing by the chimpanzees of
    Gombe, Tanzania.
    4) As long-term studies of wild chimpanzees proceeded, first in East
    Africa, then in West Africa, it became clear that populations of apes
    make and use a variety of tools, in foraging, social life, and body
    maintenance [2]. Moreover, each population has a different repertoire
    of elementary technology: some types are universal, such as
    bed-making; others are regional, such as nut-cracking in far West
    Africa [5]; and still others are unique to a single population, such
    as pestle-pounding at Bossou, Guinea. Systematic comparison across
    populations shows patterns that resemble those found cross-culturally
    when human societies are compared, for example, in that the present
    distribution of a custom reflects past diffusion from a likely single
    invention. Thus, a population's tool-kit is a technological profile of
    its material culture.
    5) Further field studies revealed that chimpanzees spontaneously use
    tool-sets: a sequence of two or more tools needed to accomplish a
    single task. The first, anecdotal description was of an A-B-C-D
    sequence, in which a stout chisel-stick (A) was used to batter the
    entrance to a bees' nest containing honey. After this, a more pointed
    chisel-stick (B) weakened the barrier at a single point; then a
    bodkin-like stick (C) pierced the barrier; and finally a slender,
    flexible probe (D) dipped out the honey. Tool-sets are cognitively
    demanding, in that a correct ordering is required: thus, a dipstick is
    only useful once the honey reservoir has been made accessible by a
    bodkin. Late reports of tool-sets elsewhere emerged, but behavioral
    data were scarce, with most information coming
    (quasi-archaeologically) from the tools left behind [].
    6) Sanz et al.[6] have now reported the use of two new tool-sets by
    chimpanzees in the Goualougo Triangle area of the Republic of Congo,
    in Central Africa. In this Congo Basin rainforest, wild chimpanzees
    tap termites from their earthen homes, using techniques that relate to
    the shape of the insects' mounds. For emergent, castle-like mounds,
    the apes perforate with a twig the mound's surface to re-open exit
    holes used by the termites. Having gained access, they use a slender
    probe to fish out the insects for food. This technique was known from
    scanty evidence, mostly of tools found at mounds, but Sanz et al.[6]
    have supplied the behavioral data to go with the artifacts.
    References (abridged):
    1. Beck, B.B. (1980). Animal Tool Behavior. (New York: Garland STPM
    2. McGrew, W.C. (1992). Chimpanzee Material Culture. Implications for
    Human Evolution. (Cambridge: Cambridge University Press)
    3. Van Schaik, C.P., Ancrenaz, M., Borgen, G., Galdikas, B., Knott,
    C.D., Singleton, I., Suzuki, A., Utami, S.S. and Merrill, M. (2003).
    Orangutan cultures and the evolution of material culture. Science 299,
    4. McGrew, W.C., Tutin, C.E.G. and Baldwin, P.J. (1979). Chimpanzees,
    tools, and termites: cross-cultural comparisons of Senegal, Tanzania,
    and Rio Muni. Man 14, 185-214
    5. Boesch, C. and Boesch, H. (1990). Tool use and tool making in wild
    chimpanzees. Folia Primat. 54, 86-99
    6. Sanz, C., Morgan, D. and Gulick, S. (2004). New insights into
    chimpanzees, tools, and termites from the Congo Basin. Am. Nat. 164,
    Current Biology http://www.current-biology.com
    Related Material:
    Notes by ScienceWeek:
    In this context, let us define "animals" as all living multi-cellular
    creatures other than humans that are not plants. In recent decades it
    has become apparent that the cognitive skills of many animals,
    especially non-human primates, are greater than previously suspected.
    Part of the problem in research on cognition in animals has been the
    intrinsic difficulty in communicating with or testing animals, a
    difficulty that makes the outcome of a cognitive experiment heavily
    dependent on the ingenuity of the experimental approach.
    Another problem is that when investigating the non-human primates, the
    animals whose cognitive skills are closest to that of humans, one
    cannot do experiments on large populations because such populations
    either do not exist or are prohibitively expensive to maintain. The
    result is that in the area of primate cognitive research reported
    experiments are often "anecdotal", i.e., experiments involving only a
    few or even a single animal subject.
    But anecdotal evidence can often be of great significance and have
    startling implications: a report, even in a single animal, of
    important abstract abilities, numeric or conceptual, is worthy of
    attention, if only because it may destroy old myths and point to new
    directions in methodology. In 1985, T. Matsuzawa reported experiments
    with a female chimpanzee that had learned to use Arabic numerals to
    represent numbers of items. This animal (which is still alive and
    whose name is "Ai") can count from 0 to 9 items, which she
    demonstrates by touching the appropriate number on a touch-sensitive
    monitor. Ai can also order the numbers from 0 to 9 in sequence.
    The following points are made by N. Kawai and T. Matsuzawa (Nature
    2000 403:39):
    1) The author report an investigation of Ai's memory span by testing
    her skill in numerical tasks. The authors point out that humans can
    easily memorize strings of codes such as phone numbers and postal
    codes if they consist of up to 7 items, but above this number of
    items, humans find memorization more difficult. This "magic number 7"
    effect, as it is known in human information processing, represents an
    apparent limit for the number of items that can be handled
    simultaneously by the human brain.
    2) The authors report that the chimpanzee Ai can remember the correct
    sequence of any 5 numbers selected from the range 0 to 9.
    3) The authors relate that in one testing session, after choosing the
    first correct number in a sequence (all other numbers still masked),
    "a fight broke out among a group of chimpanzees outside the room,
    accompanied by loud screaming. Ai abandoned her task and paid
    attention to the fight for about 20 seconds, after which she returned
    to the screen and completed the trial without error."
    4) The authors conclude: "Ai's performance shows that chimpanzees can
    remember the sequence of at least 5 numbers, the same as (or even more
    than) preschool children. Our study and others demonstrate the
    rudimentary form of numerical competence in non-human primates."
    Nature http://www.nature.com/nature
    Related Material:
    The following points are made by N.J. Emery and N.S. Clayton (Science
    2004 306:1903):
    1) Throughout folklore, the corvids (crows, jays, ravens, and
    jackdaws) have been credited with intelligence. Recent experiments
    investigating the cognitive abilities of corvids have begun to reveal
    that this reputation has a factual basis. These studies have found
    that some corvids are not only superior in intelligence to birds of
    other avian species (perhaps with the exception of some parrots), but
    also rival many nonhuman primates.
    2) Traditionally, studies of complex cognition have focused on monkeys
    and apes [1]. However, there is no reason to assume that complex
    cognition is restricted only to the primates [2]. Indeed, the social
    intelligence hypothesis [3] states that intelligence evolved not to
    solve physical problems, but to process and use social information,
    such as who is allied with whom and who is related to whom, and to use
    this information for deception [4]. There is evidence that some other
    large-brained social animals, such as cetaceans, demonstrate similar
    levels of intelligence as primates [5]. Corvids also appear to meet
    many of the criteria for the use of social knowledge in their
    interactions with conspecifics.
    3) The crow has a brain significantly larger than would be predicted
    for its body size, and it is relatively the same size as the
    chimpanzee brain. The relative size of the forebrain in corvids is
    significantly larger than in other birds (with the exception of some
    parrots) [2], particularly those areas thought to be analogous to the
    mammalian prefrontal cortex: the nidopallium and mesopallium. This
    enlargement of the "avian prefrontal cortex" may reflect an increase
    in primate-like intelligence in corvids.
    4) To fully appreciate how corvid and ape psychology are similar, it
    is important to describe how corvids may represent their physical and
    social worlds, and how these forms of mental representation may be
    similar or dissimilar to those used by apes in solving similar
    problems. The authors use the term "understanding" to convey the idea
    that corvids and apes reason about a domain (physical or social) in a
    way that transcends basic associative and reinforcement processes.
    5) Tool use is defined as "the use of an external object as a
    functional extension of mouth, beak, hand, or claw, in the attainment
    of an immediate goal". Although many birds, primates, and other
    animals use tools, it is not clear whether any of these species
    appreciate how tools work and the forces underlying their function.
    Perhaps the most convincing candidates are New Caledonian crows, who
    display extraordinary skills in making and using tools to acquire
    otherwise unobtainable foods. In the wild, they make two types of
    tools. Hook tools are crafted from twigs by trimming and sculpting
    until a functional hook has been fashioned and are used to poke out
    insect larvae from holes in trees using slow deliberate movements.
    6) The crows also manufacture stepped-cut Pandanus leaves, which are
    used to probe for prey under leaf detritus, using a series of rapid
    back-and-forth movements or slow deliberate movements that spear the
    prey onto the sharpened end or the barbs of the leaf, if the prey is
    located in a hole. These tools are consistently made to a standardized
    pattern and are carried around on foraging expeditions. The
    manufacture of stepped tools appears to be lateralized at the
    population level and tool use at the individual level.
    7) There are many aspects of corvid and ape cognition that appear to
    use the same cognitive tool kit: causal reasoning, flexibility,
    imagination, and prospection. The authors suggest that nonverbal
    complex cognition may be constructed through a combination of these
    cognitive tools. Although corvids and apes may share these cognitive
    tools, this convergent evolution of cognition has not been built on a
    convergent evolution of brains. Although the ape neocortex and corvid
    nidopallium are both significantly enlarged, their structures are very
    different, with the ape neocortex having a laminar arrangement and the
    avian pallium having a nuclear arrangement [2]. It is unclear what
    implications these structural differences have. However, cognition in
    corvids and apes must have evolved through a process of divergent
    brain evolution with convergent mental evolution. The authors suggest
    this conclusion has important implications for understanding the
    evolution of intelligence, given that it can evolve in the absence of
    a prefrontal cortex.
    References (abridged):
    1. M. Tomasello, J. Call, Primate Cognition (Oxford Univ. Press, New
    York, 1997)
    2. N. J. Emery, N. S. Clayton, in Comparative Vertebrate Cognition:
    Are Primates Superior to Non-Primates? L. J. Rogers, G. Kaplan, Eds.
    (Kluwer Academic, New York, 2004), pp. 3-55
    3. N. K. Humphrey, in Growing Points in Ethology, P. P. G. Bateson, R.
    A. Hinde, Eds. (Cambridge Univ. Press, Cambridge, 1976), pp. 303-317
    4. R. W. Byrne, A. Whiten, Machiavellian Intelligence: Social
    Evolution in Monkeys, Apes and Humans (Clarendon Press, Oxford, 1988)
    5. L. Marino, Brain Behav. Evol. 59, 21 (2002)
    Science http://www.sciencemag.org

More information about the paleopsych mailing list