APE BEHAVIOR


More than 100 different behaviors are known in chimpanzees.


TOOL USE
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).


LANGUAGE
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 "black woman".

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.
W: No
R: What do you want?
W: Candy
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).

ART
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, 1997).

LOCOMOTION
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, 1994).

DIET
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).

SEXUALITY
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.

KISSING
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).

HETEROSEXUAL INTERCOURSE
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 (Wrangham, 1994).
Female gorillas average 7 births per female while chimpanzees average 4 (Wrangham, 1994).


SELF-STIMULATION
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
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).

HOMOSEXUAL ACTIVITY
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, 1999).

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, 1999).

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).

INTERSPECIES INTERCOURSE
Bonobos can have sexual interactions with redtail monkeys in the wild. Male orangutans may have homosexual encounters with male crab-eating macaques (Bagemihl, 1999).