People of the forest (10/09/03 revision)

Flo and her "F" family, as observed by Jane Goodall and filmed by her ex-husband, Hugo Van Lawick over a period of nearly 30 years. Narration is somewhat anthropomorphic, romantic and at times pure soap opera! Observe the following as you view the video. These are the so-called "common chimpanzees" rather than the somewhat more neotenous "bonobo" or "pygmy" chimpanzee. (Anthropomorphism is attributing human traits to non-humans, generally without much thought of alternatives and implications.). These bonobos will be seen in a subsequent video.

varieties of chimps?

We should be cautious in generalizing behaviors across all chimps on the basis of observations in one locale. There are many local varieties and the environment itself selects both genetically and behaviorally. A recent report on the origin of the HIV virus suggests: ..that different subspecies of chimps harbor different strains of HIV-like viruses, and that one particular chimp subspecies found in a region that includes Gabon, Cameroon, and Equatorial Guinea is the source of human HIV-1 infections..... Science, 2/5/99.

(Note the nut-cracking video coming soon, on Western Tai forest chimps).

effects of observations -"provisioning" on chimps

Goodall used provisioning (laying out a pile of bananas) to attract chimps for better observation. But to what extent were these observations colored by the provisioning? Much ape behavior is governed by access and control of food and some of these greedy and angry displays might be very unlikely in a more natural setting. Later Jane recognized this but it seemed a good idea at the time.

1 physical structure

A. changes during maturation

contrast with human paedomorphosis . Young chimps are more like human infants than older chimps are like older humans.

B male and female differences

physical (sexual dimorphism)

Note thata female chimps are not as small as female orangs and gorillas, compared with chimp males. This reflects a different sexual/mating situation. There is no dominant chimp male who exclusively mates with all females.
behavioral sex differences

1 interest in infants
2 aggressive behavior
3 "harassment" and intimidation of females

Somewhere Franz de Waal notes that if we held chimps to contemporary human standards of sexual behavior, they all would be in the slammer! (Think about the many implications of this.) More on this later.

2 social structure

Each is part of a community of 50 animals, highly structured socially-- a "fusion-fission society.". Both kinship and aggression determine the structure that changes periodically. See "Family of Chimps" and deWaal books. He and others suggest it is the complexity of social relationships that gives chimps their intelligence. See readings by Humphrey and Cheney & Seyfarth (1990)

Some very good film of the very expressive, individual faces, close social relationships, and physical structure of face and hands utilized in these relationships. Also it is important to note that the feeding habits strongly determine structure of a species.

role of unique faces and individuality (I wonder if chimps are "specialized" for facial recognition as it seems humans are? Do they have cases of "prosopagnosia?" too?)

3 daily activities


A. knuckle walking
B. climbing
C. bipedal potential (recall differences in human adaptations for bipedalism)


Nomadic foragers moving several (2 to 6) miles per day in smaller sub-groups of close relations and "friends." These often are females with offspring.

Eating up to 7 hours per day: fruit, leaves, some insects and meat.



Probably mostly a social interaction rather than practical flea, etc. removal.

individuality seen in faces


A. very quiet unless excited (and then they are very loud!)

See pages from Goodall (1985) in readings for vocalization types

it has proven nearly impossible to train vocalizations in chimps (see the Vicki video notes.)

B. gestures and facial expressions

(Not so different from any primate.)


A. vegetation

fruits, flowers, nuts, and leaves

B. insects

fishing for termites. Note the clumsy (by human standards) skills here and elsewhere in throwing, striking with sticks, nestbuilding.

C. hunting

get the baboon! -- eat'im up! Colobus monkeys are other favorite meals when they can be hunted down.

D. nursing

continues until past 3 years--maybe to 5, gradual increase of solid foods. See the Nutcracking chimps video.

tree nest building
"rain dances"

What is this about?

sexual activities (see below)
dangers and diseases

goiter on "Ollie-longface"

polio--recall Darwin's (1871) remarks. Here is an interesting summary of human-chimp disease comparisions.

very few animal dangers (humans, baboons, leopards)

4 reproductive characteristics

1 sex organs

Behavior from morphology here too? Note the large testicles! Why so big? Note the extreme vaginal swellings when females are fertile and the relatively large visible penises when erect.

2 mating

a promiscuous society where paternity is unknown When females mature they leave the group to find another. Mothers and sons stay together.

Goodall reports that a female may elicit up to 50 matings per day! This promotes much competition among the sperm of the males mating and one can imagine various adaptations to facilitate conception.

Recent investigations of West African "Tai" forest chimps revealed using DNA to determine paternity, that a fair number of infants were sired by males not in the group and that two-thirds of infants were sired by males who had relatively high dominance sometime in their lives. (See Gagneux, P., Woodruff, D. S., & Boesch, C. (1997). Furtive mating in female chimpanzees. Nature, 387, 358-359.) Even more recent work, however, calls this into question. In any case, no chimp is likely to know who its father is!!


3 rates of reproduction

related to nursing and diet . Do chimps have anythiing like human menopause?

5 infant morphology, care and behavior

1 neoteny and paedomorphosis

Excellent examples of closer similarity to humans in body proportions, lack of hair, and feet. Note efforts to "walk" at 5 months compared with 8 to 12 for human infants. Take a good look at the newborn chimps hand, which is much like a human's compared with its mother's hand.

2 maternal care

A. clinging. attachment and security

protection-contrast with human conditions

B. role of other females than mother
C. weaning

Or lack of it in "Flint" the pathological delinquent. Generally weaning is important as it increases the mother's fertility, enabling her to conceive again. It has even been suggested that one virtue of lactose intolerance in humans is to assist in weaning. While this may be just pure speculation, it is clear that the success of our human ancestors lies largely in their ability to reproduce much more efficiently than the great apes today. Many synergistic factors are involved in this.

D. role of mother or other caretaker in acquiring skills

3 male role

There is relatively little "male parental investment" in chimp society beyond sperm contribution and some protection for the young. This is thought to be related to lack of knowledge about paternity. Some of the videos show males interacting with young ones to some extent that might serve as a "role model" for others.

6 aggression and reconciliation

1 males are dominant in aggression

but there are exceptions, especially when infants are involved

2 among other chimps within group

A. dominance

Males may become dominant by virtue of size, strength, cleverness (recall Mike banging the empty can) and importantly ability to form coalitions with other males and even females.

B. sex and communication
C. coalitions within groups including females

3 chimps outside groups
4 towards other species
5 cannibalism? Passion and Pom killings of infants

7. chimp intellect

Note examples of the following

tool use
impulsivity -(note how this relates to "intelligent" behavior
(brain similarity to humans)
(mirror experience) in readings

Chimps, like orangutans but not gorillas, seem to be able, with experience to recognize themselves in a mirror. This suggests they may have the rudiments of self-identity or even consciousness.