Evolution And History

78 CHAPTER 4 | Primate Behavior

In October 1960, the young Jane Goodall sent word back
to her mentor, paleoanthropologist Louis Leakey, that she
had observed two chimps turning sticks into tools for fish-
ing termites out of nesting mounds (or termitarias). Leakey
replied, “Now we must redefine tool, redefine Man, or ac-
cept chimpanzees as humans.”^1 Field studies of primates by
Western scientists have always contained a degree of an-
thropocentrism and a focus on what nonhuman primates
can tell us about ourselves. How and why did humans
develop as we did during the course of our evolutionary
history? Because culture, tool use, and language were
thought to be uniquely human, perhaps studies of primate
behavior might unravel an old nature–nurture question:
How much of human behavior is biologically determined
and how much of it derives from culture?
Research into primate behavior has shown again and
again the behavioral sophistication of our closest living
relatives—the anthropoid primates in general and the homi-
noids in particular. Certainly, biology plays a role in primate
behavior, but there are times that behavior is determined by
the social traditions of the groups. Of course, as with hu-
mans, nature and nurture are linked. Primates require more
time to reach adulthood compared to many other mam-
mals. During their lengthy growth and development, young
primates learn the behaviors of their social group.
While Goodall was originally criticized for giving
names to the chimps she studied (David Greybeard and
Goliath were the two chimps she first observed stripping
twigs of their leaves to fish for termites), field studies have
documented that primates know one another as individu-
als and can vary their behavior accordingly. The same is
true of many other long-lived social mammals, such as
elephants and dolphins. Observations of primates in their
natural habitats over the past decades have shown that
social interaction, organization, learning, reproduction,
care of the young, and communication among our primate
relatives are similar to human behavior.

Primates as Models

for Human Evolution

As we will explore in the human evolution chapters to
come, the human line split from a common ancestor that
we share with the African apes. Although this split occurred
millions of years ago, paleoanthropologists in the mid-20th
century were hopeful that observations made among the
living apes might shed light on the lifeways of the fossil
species they were discovering. Louis Leakey encouraged
Jane Goodall to begin her research with chimpanzees in

Gombe Stream Chimpanzee Reserve

(now a national park) on the

eastern shores of Lake Tan-

ganyika in Tanzania for

this reason.

But the forest ape be-

havior model appeared

flawed to the paleoan-

thropologists of the past.

The fossil evidence indi-

cated that the earliest hu-

man ancestors inhabited

a grassy savannah envi-

ronment rather than the

tropical forests inhab-

ited by the apes. Instead,

paleoanthropologists turned to baboons: a group of Old

World monkey species that inhabit the savannah environ-

ments of eastern Africa where the richest fossil evidence

of our ancestors had also been found. While the savan-

nah environment has certainly been important in human

evolution, recent fossil discoveries and analyses have lead

paleoanthropologists back into the forest. The earliest two-

legged ancestors inhabited a forested environment and

have lead paleoanthropologists to investigate the human

origins in terms of the transition from forest to savannah.

Though baboons differ considerably from our two-

legged ancestors, their survival strategies provide some

clues as to how our ancestors adapted to the savannah envi-

ronment. Members of the genus Papio, baboons are among

the largest of the Old World monkeys. Fully terrestrial,

troops of baboons can be seen sitting together on the dry

savannah earth to forage for corms (thick, nutritious un-

derground reproductive parts of plants). They keep a

watchful eye out for predators while feeding. At the first

sight or sound of danger, alarm calls by members of the

troop will signal for all the individuals to retreat to safety.

Baboons live in groups that vary dramatically in size,

from under ten to hundreds of individuals. In some spe-

cies the groups are multi-male multi-female while others

are made up of a series of harems—one male with several

females that he dominates. Sexual dimorphism— anatomical

differences between males and females—is high in baboons,

and therefore males can use their physical advantages to

overpower females easily. But the degree to which males

choose to do so varies from group to group.

Extrapolating from baboons to theories about our an-

cestors poses problems. To use the words of primatologists

Shirley Strum and William Mitchell, these baboon “models”

often became baboon “muddles.”^2 Paleoanthropologists

MALAWI

BURUNDI

RWANDA

MOZAMBIQUE

TANZANIA

Gombe Stream

National Park

ZAMBIA

ZANZIBAR

CONGO

UGANDA

KENYA

Mt.

Kilimanjaro

Lake

Tanganyika

Indian

Ocean

(^1) Jane Goodall Institute. http://www.janegoodall.org/jane/study-corner/
Jane/bio.asp. (accessed June 16, 2009)
(^2) Strum, S., & Mitchell, W. (1987). Baboon models and muddles. In
W. Kinsey (Ed.), The evolution of human behavior: Primate models.
Albany: State University of New York Press.