A Comparison of Some Similar Chimpanzee and Human Behaviors
Bonobo Peace Keeping
Description: Aggressive behavior is typical of most primates. Gorillas,
humans and chimpanzees kill members of their own species. The need for
social and physical contact is also characteristic of most primates.
Species that live in groups need to reconcile aggression. Social groups
require some form of conflict resolution. Sexual behavior is one such
mechanism to overwhelm aggression.
Bonobo sex life is divorced from reproduction and also serves the functions
of pleasure and conflict resolution. Females are in a sexually attractive
state most of the time, and almost continuously sexually active. Sexual
activity is very frequent. Males, females and juveniles all engage in
erotic activity. Age and gender are not sexual boundaries among the
Bonobo. A typical sexual pattern is genital rubbing between adult females.
Erotic contacts in Bonobos includes oral sex, genital massage and intense
tongue-kissing.
Whereas in most other species sexual behavior is a fairly distinct
category, in the Bonobo it is part and parcel of social relations. Sex
seems to cement Bonobo bonds. Females use sex to form alliances against
males. Consequently males do not dominate females or coerce them sexually.
Bonobo culture is female-centered, egalitarian and substitutes sex for
aggression.
Context: Bonobos live in groups of 50 to 120 animals. Bonobo society
appears to be female-dominated. Male status is linked to that of his
mother. Older females occupy the highest rank. The strongest social
bonds are between females. Raising offspring is an exclusively female
activity.
In Bonobo society sexual excitement and aggression
rates are higher at feeding times. Dominant males may delay sharing food
with females who are not sexually disposed. Cofeeding takes place between
intimates. Among Bonobos, embracing, friendly touching and sexual contact
rates jump after an aggressive incident. According to zoologist Frans
de Waal, "The majority of mounts and matings occur in tense situations." "(C)onflict
resolution is the more fundamental and pervasive function of Bonobo
sex." Sex in Bonobo society is definitively a mechanism for keeping
the peace.
Bonobo-Human Comparisons: Human nuclear families are presumably incongruous
with the sex habits found in Bonobo culture. Many of the roots of human
behavior can be traced to our primate heritage, including survival through
cooperation and mutual assistance. While the same mechanisms and purposes
may underlie Bonobo and human social behavior, distinct solutions have
evolved in these two groups. In particular, humans and Bonobos have
developed different mechanisms for peacekeeping. Cultural transmission
and highly developed symbolic language are particularly unique to humans.
Human conflicts and aggression are typically reconciled and avoided
through language.
The use of sex to reconcile or avoid conflict is present in human culture,
though it is nowhere near as pervasive a factor as among the Bonobos.
Conflicts are less likely to recur after body contact between aggressors.
This similarity to Bonobo use of sex can be seen in the custom of adversaries
shaking hands after conflict, or close friends kissing and making up
after a fight. Intimate human couples engage in sexual activity after
conflicts. Sexual receptivity maintains pair bonding in humans much
as it does group cohesion in Bonobos.
Unlike Bonobos, sexual control is evidenced in humans. Marriage typically
serves as a sexual control mechanism. Human males participate in child
rearing and, due to monogamous marriages, have some assurance of paternity.
In most cultures men honor proprietary rights of husbands over their
wife or wives. Marriage typically involves exclusion and control over
a female's sexual life. Humans also demonstrate sexual coercion and
jealousy between intimates. Most human cultures are male-dominated.
Symbolic Communication
Description: Apes are physically unable to produce human speech, so
investigation of their ability for symbolic communication has been difficult.
Gardner and Gardner taught American Sign Language (ASL) to Washoe, and
subsequently to four other chimpanzees. Washoe's instruction began at
age one and continued for five years. Washoe learned 132 signs and formed
novel combinations of signs. Other researchers, notably Francine Patterson
and Roger Fouts, also instructed Chimpanzees to use ASL. E. Sue Savage-Rumbaugh,
in the Animal Model Project, improved on the ASL system with lexigrams
and a symbol keyboard system (accompanied by special lighting on the
keyboard, image projection and accompanying sounds to correspond to
the symbols).
Savage-Rumbaugh taught two chimps, Austin and Sherman, lexigrams to
symbolize tools needed to acquire food, among other symbols. Using only
the lexigrams, Austin and Sherman had to communicate which tool was
required to access food. Their success rate was 97 percent correct when
the keyboard with lexigrams was available, and dropped to 10 percent
with the keyboard turned off. This established that their communication
was indeed symbolic. Sherman and Austin had learned to communicate with
each other through the use of learned symbols in the setting of cooperation
to obtain food. These experiments established that chimpanzees are capable
of acquiring or learning symbolic communication.
Context: The benefits of communication can be learned along with an
awareness of the benefits derived therefrom, such as success in food
acquisition. Austin and Sherman learned to communicate symbolically in
a human experimental setting. They have shown the cognitive capacity
to realize that communication can alter the behavior of others, and
they used this capability to obtain food. We cannot as easily ascertain
if symbolic communication occurs in ape societies in the wild. We know
that vocalizations are an important aspect of chimpanzee life, yet we
have no proof that they are employed in a highly symbolic fashion as
is the case with human language.
Human Comparisons: The human mind evolved from the earlier hominid
mind, and that diverged from the ape mind. Human cognitive processes
had their direct antecedent in the ape brain. Chimpanzees resemble humans
more than any other animal with regard to mental processes. Except in
regard to size, human brains are very alike to chimpanzee brains. The
major differences between humans and apes are not anatomical, but rather
behavioral. The most significant behavioral difference in humans is
the complex uses of objects and language. Human children refer to items
in a representational manner at an early age. Chimpanzees do not show
this behavior. This does not imply a lack in apes of the cognitive abilities
which facilitate this behavior in humans.
Humans definitely use symbolic communication to acquire
food and other resources. We have the cognitive capacity to realize that
communication can alter the behavior of others at an age before we can
uttering one word sentences. We very readily understand that saying, "Please pass
the salsa," alters the behavior of others.
In humans the capacity for symbolic communication has evolved to surpass
the level of this capacity in our ape cousins. Our reasons for and use
of symbolic communication is far greater and more diverse than in the
apes, to the best of our knowledge. If symbolic vocalizations occur
at all among apes, only an understanding of primate vocalizations can
enlighten us of the actual degree of this important difference between
our species.
A cooperative resource sharing strategy and group planning in our common
ape ancestors probably fueled reproductive success and evolution to
greater mental capacities related to communication and language in humans.
Our very evolution evidences the ability for symbolic communication
in humans.
Medicinal Plant Usage
Description: Detailed evidence for the use of medicinal plants in the
chimpanzee has been recently documented (Huffman). Chimpanzees are susceptible
to parasites that also infect humans. Parasite study identified nematodes,
trematodes and protozoae as chimpanzee parasites. Two types of medicinal
plant use, whole leaf-swallowing and bitter pith chewing are known in
chimpanzees.
Sixteen plant species of possible medical use have been observed and
identified to be ingested by chimpanzees across equatorial Africa. This
behavior has also been observed in the Bonobo and the eastern lowland
gorilla. Analysis of the feces collected from individuals observed leaf-swallowing
revealed that they were suffering from parasite infections. Plant specimens
were collected concurrently with observations of their use. The chemical
and physical properties of the plants were analyzed. In some cases worms
were expelled with leaves. Some of the worms were actually firmly stuck
to the surface of the leaf. Anti-parasite activity due to chemicals
produced by these plants (whole leaf swallowing) was ruled out. Short
hairs located on the leaves appear to be responsible for the eviction
of the parasites. Chimpanzees select these plant species for their physical,
roughness properties, resulting in the physical purging action of adult
parasites by the leaves. Thus whole leaf swallowing is one self-medication
strategy used by chimpanzees against gastrointestinal parasites.
Bitter leaf-chewing is another method. Infection of parasites drops
noticeably after chewing of Vernonia amygdalina pith. Chemical
analyses has revealed sesquiterpene lactones and new steroid glucosides
with antiparasitic activity against Schistosoma, Plasmodium and
Leishmania.
Context: Field observations have shown that ill chimpanzees consume
the remedial plants. Incidence of the medicinal plant use is higher
during the rainy season when parasite infections are also at their highest.
Chimpanzees have learned to distinguish between harmful plant parts
and parts that contain beneficial compounds. This behavior is learned
from other group members, which allows the group to benefit from the
experience of an individual.
Human Comparisons: The WaTongwe people also traditionally use V.
amygdalina as a treatment for similar symptoms. Among other African
peoples this plant is used for stomach aches and parasite infections.
The leaves of a domesticated variety is used as a food in order to restore
stamina. This is one example of the pervasive use of medicinal plants
among humans. The chimpanzee practice of parasite removal by use of
the physical properties of leaves has not been documented among humans.
Many populations in the Amazon Basin use Banisteriopsis for
its purgative and evacuative effect, an analogous activity with a somewhat
different mechanism and more profound side effects. While living in
the Amazon basin this author also discovered the use of a tea with anesthetic
properties to be totally efficacious in curing an infection which was
likely amoebic dysentery. The active ingredient was found in the root
bark of a small plant.
Most interestingly, it is possible to acquire new medicines and new
medical techniques for humans by watching the behavior of sick animals.
Sources:
de Waal, Frans, Peacemaking among Primates, Harvard University
Press, Cambridge, Massachusetts, 1989.
de Waal, Frans B. M., Bonobo Sex and Society, Scientific American,
March 1995, pp. 82-88, accessed via: http://soong.club.cc.cmu.edu/~julie/bonobos.html.
Huffman, Michael A., The Medicinal Use of Plants by Chimpanzees
in the Wild, Primate Research Institute, Kyoto University, Japan,
http://jinrui.zool.kyoto-u.ac.jp/CHIMPP/CHIMPP.html.
Jacobs, James Q., A Brief Note Regarding Campa Medical Practices,
http://www.jqjacobs.net/writing/ethnomed.html
Primate Behavior, http://www.leeds.ac.uk/chb/lectures/anthl_11.html.
Pan paniscus, Bonobo or pygmy chimpanzee, Animal Diversity Web,
University of Michigan, http://www.oit.itd.umich.edu/projects/ADW/.
Pan troglodytes. Chimpanzee, Animal Diversity Web, University
of Michigan, http://www.oit.itd.umich.edu/projects/ADW/.
Savage-Rumbaugh, E. Sue, Ape Language, Columbia University Press,
New York, 1986.
Smuts, Barbara, Commentary - Apes of Wrath, Discover Magazine,
August 1995.
The Evolution of Morality, Yerkes Regional Primate Research
Center, http://www.emory.edu:80/YERKES/NEWSROOM/dewaal.html, August
30, 1996.
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