More than 100 different behaviors are known in chimpanzees.
After Jane Goodall told Leakey that wild chimps make and use tools, he
replied "Now we will have to redefine tool, redefine man, or accept
chimps as man."
Humans are not the only animals to use tools. Tool usage is especially
common in chimps: sticks for termites, wad of chewed leaves to remove
water from tree holes, stout sticks to dig up ant, bee, or termite nests,
leafy branches for sandals or gloves, leaf cushions to protect from thorny
branches, bone picks to extract bone marrow, leaf napkins to clean themselves
and infants, leaves to scoop water, natural objects to carry water, and
mortar and pestle to smash palms. Not all chimp populations have the same
practices/tool usage-- these are passed down in each population as a learned
behavior. Chimpanzees regularly use tools in all parts of their range
and in all habitats. In captivity they have created flaked stone tools.
There are differences in the tool usage in different populations which
some have considered to represent a primitive sort of culture (McGrew,
1992; Fouts, 1997). A greater frequency of nut smashing has been observed
in chimpanzees in far West Africa while ants compose a greater part of
the chimp diet in East and Central Africa. Some populations hunt a greater
percentage of adult colobus monkeys while others hunt a greater percentage
of infant colobus (Wrangham, 1994).
Although chimps and other primates have a greater capacity for tool use
and language ability than is observed in their wild behavior (Guy, 2006).
Tool use occurs in a variety of animals but is most advanced in chimps
(Pruetz, 2007). Chimps are the only animals other than humans which habitually
use tools to hunt vertebrate animals. Male, female, and immature chimps
have been observed to fashion spear-like tools from tree branches to hunt
for nocturnal prosimians hiding in the crevices they hide in during the
day. Tool preparation can include several steps such as trimming off side
branches and trimming the tip of the spear (Pruetz, 2007).
Stone tools have been identified in an African rainforest which date
to more than four thousand years old. The structure of the tools and nut
remains (which include sources typically used by chimps and others used
exclusively by chimps) indicate that these were used by chimps rather
than by humans. Modern chimps in the region continue to use rocks for
nut cracking, suggesting that this behavior has been passed on for more
than 200 generations. The concept of a "Chimpanzee Stone Age"
leads to the interesting hypothesis that the use primitive stone tools
might have arisen prior to the first hominids (Mercader, 2007).
With the exception of the use of shelters to protect from rain, tool
usage is not as common in Bonobos as it is in common chimps. Gorillas
and gibbons have also not been observed to use tools extensively, although
in none of these species have the studies been as extensive as those observing
common chimpanzees. In captivitiy, orangutans have learned to manipulate
fire (McGrew, 1992).
There are gender differences in the tools used by common chimpanzees.
Females spend more time extracting termites and ants and thus use these
materials more frequently. Males are more likely to use sticks and stones
as weapons (McGrew, 1992).
Chimps, gorillas, and orangutans all build nests and this behavior is
not known in any other species of catarrhine primate. Gorillas build their
nests on the ground while both species of chimpanzee and orangutans build
tree nests. In Bonobo chimpanzees, females make their nests higher in
trees and they require more time to build them (Wrangham, 1994).
An 18th century Cardinal once said to a chimp "Speak and I shall
baptize thee." (Some families which have kept chimps have baptized
them without speech.)
Because the human head is held upright over the spinal cord, the pharynx
and oral cavity meet at almost a 90 degree angle unlike the slope present
in other apes. This determines the repertoire of sounds which can be produced.
The tongue and larynx are anchored lower in the neck. Although there have
been attempts to teach apes to talk vocally (with a few words mastered),
their tongues are too thin and the larynx too high to permit much success
anatomically. Apes are also fairly quiet in the wild so this isn't a natural
behavior (Savage-Rumbaugh, 1998; Fouts, 1997). Sign language is also more
difficult for non-human apes since the hands are also used for quadrupedal
locomotion and not as dexterous as human hands (Savage-Rumbaugh, 1998).
In 1967 Adriann Kortlandt identified the use of hand-signs in wild populations
of chimps, with 3 different populations had 3 different "stop"
signs (Fouts, 1997).Chimp signs consistent with our definition of language
(Bodamer, 2002; Fouts, 1997). Chimps can understand some human speech
and recognize affective aspects of human speech. Sign language has been
taught to gorillas, common chimpanzees, and Bonobo chimpanzees (Savage-Rumbaugh,
1998; Savage-Rumbaugh, 1986). Common chimpanzees and bonobos use similar
facial and vocal signals. In contrast, gestures are more variable within
a species and between the two species and are thus probably under a greater
amount of voluntary control. Monkeys use facial and vocal signals but
not gestures. It is possible that the use of gestures in apes laid the
foundations for human language (Pollick, 2007). Twenty-five hand signals
are known in to occur in Bonobo sex (Bagemihl, 1999).
Dan Fouts has spent decades teaching chimpanzees sign language. He began
with a chimp named Washoe. At 10 months Washoe combined signs "Gimme
sweet", "Come open"; and later "you me hide."
Washoe and Lucy invented new signs that they had not been taught (even
when their trainers used a different set). Their toilet was called "dirty
good", the refrigerator was "open food drink", watermelon
was "candy drink" and "drink fruit", radish was "cry
hurt food", and swan was "water bird." Contrary to expectations,
only 5% of the observed chimp conversations were about food (Fouts, 1997).
By age 5, Washoe was using 132 signs and understood hundreds of others.
When tested to determine her accuracy, she received scores of 71% to 86%.
The random use of signs would have produced accuracies well under 5%.
Even when she was mistaken, there was the indication of understanding--she
might mistake "comb" for "brush" or "nuts"
for "berries" but not "comb" for "berries."
Washoe understood word order such as the difference between "me tickle
you" and "you tickle me". Washoe "read out loud"
--signed to herself while reading a magazine alone and identified pictures.
On seeing other chimps for the first time and asked what they were,Washoe
called them "black bugs". After getting to know one, she became
During her second pregnancy, when asked "what in your stomach?",
Washoe replied "baby, baby" and cradled her arms. When taking
care of a 10 month old infant (to replace hers which had died), she at
first said "come baby" and taught him a sign on her 8th day
with him. Washoe repeated signs over and over with him; Loulis was regularly
signing to humans and chimps after 8 weeks, all signs were learned from
Washoe (the humans were taking care not to sign). This was the first nonhuman
to teach a human language to another nonhuman (Fouts, 1997).
The following is a sample conversation between Roger Fouts (human)
and Washoe from Fout's book Next of Kin:
R (looking at watch anxiously): You me go home now.
R: What do you want?
R: OK. OK. You can have candy at home.
W (very happy): You me hurry go.
The following passage is also taken from Next of Kin:
One of our long time volunteers, Kat Bach, once told me that when she
first met Washoe she was amazed that a chimpanzee could use human language.
But after getting to know the chimps, she was instead amazed by what
Washoe communicated. In the summer of 1982 Kat was newly pregnant, and
Washoe doted over her belly, asking about her BABY. Unfortunately, Kat
had a miscarriage, and she didn't come to the lab for several days.
When she finally came back Washoe greeted her warmly but then moved
away and let Kat know that she was upset that she'd been gone. Knowing
that Washoe had lost two of her own children, Kat decided to tell her
the truth. MY BABY DIED, Kat signed to her. Washoe looked down to the
ground. Then she looked into Kat's eyes and signed CRY, touching her
cheek just below her eye. That single word CRY, Kat later said, told
her more about Washoe than all of her longer, more grammatically perfect
sentences. When Kat had to leave that day, Washoe wouldn't let her go.
PLEASE PERSON HUG, she signed (Fouts, 1997).
OTHER COMPLEX THOUGHTS
Plato felt that only humans remembered the past and planned for the future.
In Fouts' chimp group, one begins asking for "candy tree" (Christmas
tree) almost every year after Thanksgiving; one asked for "bird meat"
(Thanksgiving) after Halloween. The chimp Dar had her "birthday"
the day after a human researcher's birthday, after the person's birthday
party a chimp asked "ice cream Dar?" (Fouts, 1996)
Apes are the only animals other than humans which recognize their own
reflection in mirrors.
Washoe once jumped an electric fence to save a human in trouble by the
edge of water (Linden, 1986).
Chimps paint enthusiastically in captivity and title own their paintings.
Washoe had a painting named "Electric Hot Red". Tatu wouldn't
stop an unfinished painting, not even for dinner while other chimps were
less inclined and might even eat the paints. Since chimps could "talk"
about their paintings (using sign language), it was shown that the ability
to paint representationally was shown not to be human-specific (Fouts,
Bonobo locomotion involves more hanging and leaping than that of the common
chimp. Different populations vary in the percentage of time spent using
bipedal/quadrupedal locomotion and the amount of time spent in trees (Wrangham,
Chimpanzees are known to eat 25 species of mammals; the 11 species of
primate which are included in their known prey include human infants and
cannibalism of other chimps (McGrew, 1992). Chimpanzees can kill prey
which weigh up to 20 kg (45 pounds) (De Waal, 2001). Chimpanzees seem
to utilize medicinal plants when they are sick (Wrangham, 1994).In determining
which chimps eat meat after a kill, age and kinship are determining factors.
Females in estrus receive more meat than other females (McGrew, 1992).
ARE CHIMPS HUMAN?
Of course not. Humans are unique in many wonderful ways and no one is
arguing otherwise. However, the separation between humans and other animals,
particularly the apes was once perceived as some gaping chasm of qualitative
differences. Now, as we better understand humans and other animals, the
distance between us is nowhere near as great as was once thought.
VIOLENCE IN APES
Biologically, humans are most closely related to apes and descriptions
of ape violence can suggest parallels to human violence. An estimated
10% of gorilla infants are killed by an adult male gorilla who displaces
another male as leader of a harem of females. The majority of males commit
infanticide at least once during their lives and most females will have
an infant killed by an adult male gorilla (Bagemihl, 1999; Wrangham, 1996).
Chimps can attack each other in lethal gang attacks. High ranking female
chimps have been observed to kill low ranking females and to commit infanticide
of the offspring of low-ranking females. Aggression is often displayed
towards immigrant females. High-ranking females mature faster than low
ranking females, perhaps because they are better nourished (De Waal, 2001).Male
chimpanzees are known to kill the infants of chimpanzees who belong to
other groups. A few cases are known in which males killed infants in their
own group if the female was a new immigrant to the group. Infanticide
was not committed on the offspring of immigrant females once they had
mated with the males of the group (De Waal, 2001). Female chimpanzees
can also commit infanticide, perhaps motivated by competition with other
females (Muller, 2007).
Chimpanzees and humans are unusual among animals in that they are prone
to kill individuals of their own species which belong to different social
groups (De Waal, 2001). In 1974, the first case in which non-humans deliberately
sought for an individual of their own species in order to attack and kill
them was recorded. A group of common chimps silently passed into the territory
of a neighboring group, encountered a solitary male, and beat him to death.
In 1977, the members of one group of common chimps fatally assaulted the
males of a neighboring group one by one over time and abducted the females
until the neighboring group no longer existed (Wrangham, 1996).
Compared to common chimpanzees, Bonobo males are less aggressive and
form closer bonds with females which are not limited to the period of
estrus. Unlike common chimp males, Bonobo males do not form lethal raiding
parties or commit infanticide (Savage-Rumbaugh, 1998).
In both orangutans and common chimpanzees, heterosexual intercourse can
involve forceful coercion of the female. In orangutans, female coercion
may be a factor in as many as 1/3 of matings. Once, an orangutan male
raped a human woman. In common chimpanzees, females can be assaulted by
males of the group which apparently results in a female being more likely
to submit to the male (Wrangham, 1996).
Many of the earliest artifacts of human culture (such as cave drawings
and sculptures) indicate that humans have been preoccupied with sex for
as about as long as there have been humans. For thousands of years, human
cultures have also been concerned with identifying what each culture felt
were appropriate expressions of sexuality and which expressions were inappropriate.
Often, the justification for the appropriateness of sexual acts centered
on whether or not it was "natural". As our understanding of
animal sexuality has increased, the variations of sexual behavior which
occur in nature (and thus are "natural" in the original sense
of the word) has grown.
Open mouth kissing (including same sex kissing) occurs in Bonobo chimps,
common chimps, and squirrel monkeys. Open mouth kissing can be intense
in Bonobos (Bagemihl, 1999; Fouts, 1997).
Apes have displayed a diverse array of sexual practices, some of which
were previously thought to be unique to humans. These include the "missionary"
position (Orangs and Bonobos; common chimps do rarely while this is the
position of 1/3 of Bonobo matings), a variety of sexual positions (Bonobos);
and sex used for purposes other than procreation (to reconcile, make friends,
and calm tension in Bonobos; in exchange for food in common chimps).
In gibbons, Bonobos, and Old World monkeys, sexual activity can occur
when females are not able to conceive. Bonobo females are continually
sexually receptive (Savage-Rumbaugh, 1998). Face to face intercourse occurs
in gorillas, Bonobos, gibbons, and dolphins. Anal stimulation frequently
occurs in heterosexual encounters between orangutans Bagemihl, 1999).
The former name for chimpanzees was Pan satyrus for their sexual activity.
In a colony with four males, a female may mate six times a day during
estrus (although the mating typically lasts for less than 15 seconds).
Dominant males mate more frequently than males of lower rank. Females
experience climax (De Waal, 1982). Female common chimpanzees may mate
several hundred times per conception. (Bagemihl, 1999).
Bonobos engage in sexual activity more frequently than in common chimpanzees
and this activity plays a factor in female relationships and group cohesiveness
Female gorillas average 7 births per female while chimpanzees average
4 (Wrangham, 1994).
Clitoral rubbing in bonobo chimps, rhesus monkeys, and gorillas.
Female penetration can involve fingers, tails (dolphins), an erect clitoris
(Bonobo chimps), and foreign objects . Mutal masturbation occurs in macaques.
Masturbation is known in in gorillas, rhesus monkeys, macaques, vampire
bats, and proboscis monkeys (Bagemihl, 1999). Lucy (a chimp) would masturbate
with a vacuum cleaner (after plugging it in) and would "read"
National Geographic regularly until estrus at which time she preferred
Playgirl (Fouts, 1997).
Oral sex which involves sucking occurs in Bonobos, orangutans, siamangs,
stumptail macaques; licking more common in animals as diverse as hyenas,
cheetahs, sheep, and vampire bats (Bagemihl, 1999).
Same-sex sexual activity is known in more than 450 kinds of animals including
representatives of every major group of animals and every continent of
the world. Same-sex contact includes lip contact and open-mouth kissing
(Bagemihl, 1999). Male anal intercourse occurs in orangutans, bonobo chimps,
rhesus monkeys, bison, and bighorn sheep. Same sex pairs may raise young,
especially in birds.
Same-sex mounting and genital manipulation has been observed in a number
of species of New World monkeys. Same-sex mounting has been observed in
some prosimians. (Bagemihl, 1999).
All female Hanuman langurs have same-sex relationships (Bagemihl, 1999).
Amoung macaques, most females are bisexual while many are heterosexual
and some are exclusively homosexual. In an number of Old World monkeys
and apes, the frequency of homosexual encounters varies from population
to population (Bagemihl, 1999).
Homosexual activity in orangutans includes male anal intercourse, oral
genital contact, kissing, and manual masturbation. Most males probably
bisexual, at least when young and most females are bisexual (Bagemihl,
Gorilla females and males frequently engage in same-sex affectionate
relationships, often with a particular individual of the group. In both
males and females, same-sex interactions last longer than heterosexual
ones and more frequently use face to face interactions as opposed to mounting
from the rear. Most males are bisexual (at least when young and in all-male
groups) and some are exclusively heterosexual or homosexual. There is
variation among females as to whether they are bisexual, predominantly
heterosexual, or predominantly homosexual (Bagemihl, 1999).
About 1/3 of the mounting between common chimps occurs between males.
Manual stimulation and same-sex kissing can also be common in males and
females. In some populations, almost all males may participate in homosexual
activity. Some individuals seem to have a homosexual orientation (Bagemihl,
Bonobo chimps utilize G-G rubbing, orgasm, female group sex, anal stimulation,
oral sex, same sex kissing; 40 to 50% of sexual activity is homosexual
and almost all bonobos are bisexual. (Bagemihl, 1999).
Bonobos can have sexual interactions with redtail monkeys in the wild.
Male orangutans may have homosexual encounters with male crab-eating macaques