Inside a Chimpanzee Community
Chimpanzees and
humans are both very social species. We both surround ourselves with
family members and close companions, even individuals we don’t get
along with. Although we are similar, the structure of the social
interaction of humans and chimpanzees can vary quite significantly.

Chimpanzees have a complex social structure called a
fission-fusion
society. An example of a fission-fusion society you can think of a
group of college students residing at a campus. During the day,
groups of students have different classes, and may hang out
together, scattered on the campus grounds. At night, all of the
college residents come back to the dorms to sleep. This is like
chimpanzees in that, chimpanzees live in a large community with
different subgroups that break apart during the day but come
together in a central location at night to sleep. They will disperse
themselves in these smaller groups to find food throughout their
forest territory. These subgroups will then congregate in their
large community and sleep near each other, up in the trees, at
night. The subgroups will
switch constantly, with different chimps spending time together day
to day. As humans, we do this too. On different days, we may spend
time with different groups of friends or family members.
.JPG)
A chimpanzee
community consists of adult males and females with adolescents
offspring. The size of the subgroups can change depending on the
chimpanzees’ activity. For example, a hunting party will have a
large number of chimpanzees because it is easier to catch prey with
more hunters. Foraging parties also have a large number of
individuals when food is plentiful. While traveling from one food
source to another, chimpanzees may be in small groups or alone
because individuals travel at different speeds. Even in our lives,
the number of individuals we spend time with varies with our day to
day activities.
Male chimpanzees
often spend their entire life in the community they were born in,
whereas female chimpanzees may travel to different communities.
Males tend to be more social than females and prefer each other’s
company but females tend to be less social and spend most of their
time with their young. Females tend to find food alone instead of in
groups because of food competition. Females need to spend their time
taking care of their young and cannot waste energy fighting over
food. Male chimpanzees are able to fight over food because they do
not take care of the young.
Chimpanzee
society is dominated by male strength. The adult males of a
community will fight for the top ranking position called an alpha
male. Usually the alpha male is the strongest chimpanzee in the
community but this is not always the case.

Some male chimpanzees
are not strong enough to overtake the position as alpha male by
physically fighting, so they overtake the position with their
smarts. A male chimpanzee can gain support from the other
chimpanzees in the community. If enough chimpanzees favor one male
over the alpha male, then the community can help the favored male
take the position as alpha male. When a male is in the alpha
position, he often displays his strength. When his hair sticks
straight up we call this piloerection he does this to make
himself look bigger and he runs around making loud shrieking
vocalizations. He may break branches off trees and throw rocks
to intimidate the other chimpanzees and help him keep the power he
has within the group. Could
you imagine throwing a temper tantrum every time you wanted to get
everyone to respect you? It would get pretty tiring after a while.
Chimpanzees lower in rank than the alpha male will offer their hand
while grunting to the alpha male as a sign of submission. The
position of alpha male is never permanent and often changes from
male to male.
Female
chimpanzees also have a dominance hierarchy in the group in order to
gain first access to food and other resources. Their status is not
as extreme as the males. A dominant female’s offspring will inherit
the status of her mother. Have you ever met someone who was born
into a wealthy or highly respected family? Well, that gain of status
can be paralleled to this phenomenon in chimpanzees.
The male has to
be accepted by the females before he can gain his status. Females
can be very choosy and if the females do not like approve of the
alpha male they will not let him mate with them. Females provide all
the care for their offspring and they do not want a male as their
leader unless he is the one they feel can best provide for the
group. Females can choose to support another male they see being a
better leader for the group. So it’s important for males to have
good relationships with the females of the troupe.
Chimpanzees are
very territorial. Different communities live in different parts
of the rainforest. When a chimpanzee community is on the
boundary of their territory conflicts can arise between
chimpanzee communities. Mother chimpanzees with babies have to
be cautious on the territory edges because often babies will be
killed by other chimpanzees from neighboring communities.
Aggression usually doesn’t occur within the community unless it
has to do with fighting for the alpha male position or fighting
over females.
A female
chimpanzee becomes more social when she is ready to mate. Usually
when a female is ready to mate when there is food readily available.
This benefits the female because the female needs more food to
support her baby chimp. The female has 10-12 days available to mate
and become pregnant. During these days male chimpanzees may fight
over the female. Usually, the alpha male gets the opportunity to
mate with the female. A male chimpanzee will shake a branch to
invites the female to mate with him. When a female is ready to mate,
a male may guard her so no other male can mate with her. After the
female is pregnant, the male has nothing to do with the baby or
mother. We humans, unlike chimpanzees are monogamous and usually
both the male and female will contribute to raising the child.
Message from CAC'ers
When we were in Tanzania, we got the great
opportunity to see a fission-fusion society at work. We
spent three days in Mahale and three days at Gombe. In both
places we saw certain recognizable individuals each of the
three days we were there. It was really cool to take note
that different individuals were hanging out with each other
from day to day. We even got to see males doing their
dominance displays! We sure thought it was
intimidating!
|
|