• New World monkeys, such as the marmosets, spider monkeys, and howler monkeys

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• New World monkeys, such as the marmosets, spider 
monkeys, and howler monkeys;
• Old World monkeys, such as macaques, baboons, and
colobus monkeys; and
• The hominoids, which comprise apes and humans.
(Monkeys and apes are known collectively as anthropoids.)
Twenty-eight of the 200 modern primate species live in
Madagascar (the lemurs), with approximately 50 species
each found in Central and South America, Africa, and Asia.
Apart from humans, there are no native, modern primate
species in Europe, North America, or Australia. (See figure
10.1.)
Modern primate species constitute an extraordinarily 
varied order, in terms of both morphology and behavior.
Some species are among the most generalized and primitive
of all mammals, while others display specializations not seen
in other mammalian orders. Nevertheless, primate bodies 
are generally primitive. True, some have lost tails and others
have developed large brains. None, however, has turned
hands into wings (as bats have), or reduced fingers and toes
to single digits (as horses have), or lost limbs altogether (as
baleen whales have, being without hindlimbs), or trans-
formed its dentition into something that no self-respecting
primate would put into its mouth (as the baleen whales have,
with their hairlike combs designed for filtering tiny prey out
of water).
Modern primates vary enormously in size, ranging from
the diminutive mouse lemur, which weighs in at 80 grams, 
to the male gorilla, at more than 2000 times the mouse
lemur’s size. Whatever their size, primates are quintessen-
tially animals of the tropics (see figure 10.2). Although dif-
ferent primate species occupy every major type of tropical
environmentafrom rainforest, to woodland, shrubland,
savannah, and semidesert scruba80 percent of them are
creatures of the rainforest. Several Old World monkeys and
one apeathe mountain gorillaalive in temperate and even
subalpine zones. Among primates, Homo sapiens is unique in
ranging so wide geographically and in tolerating so extreme a
variety of environments.
Primates, the order to which humans belong, are extraordinarily 
varied, in their size, mode of locomotion, and diet. Grasping hands,
enlarged brain, hindlimb-dominated locomotion, and low reproduct-
ive potential are some of the characteristics that define what it is to be
a primate. The origin of the order is still a subject of discussion.
Homo sapiens is one of approximately 200 species of living 
primate, which collectively constitute the order Primates.
(There are 22 living orders in the class Mammalia, which
includes the bats, rodents, carnivores, elephants, and marsu-
pials.) Just as we, as individuals, inherit many resemblances
from our parents but also are shaped by our own experi-
ences, so it is with species within an order. Each species
inherits a set of anatomical and behavioral features that char-
acterize the order as a whole, but each species is also unique,
reflecting its own evolutionary history.
Matt Cartmill, of Duke University, says of anthropology:
“Providing a historical account of how and why human
beings got to be the way they are is probably the most import-
ant service to humanity that our profession can perform.” An
understanding of our primate heritage provides the starting
point for writing that historical account. In this unit we will
consider what it is to be a primate, in terms of anatomy and
behavior.
The study of primatesaprimatologyahas undergone
important changes in recent years for two reasons. First, 
ecological research has been thoroughly incorporated into
primate studies. As a result, primate biology can be inter-
preted within a more complete ecological context. Second,
the science of sociobiology has enabled a keener insight 
into the evolution of social behavior (see unit 13). And 
primates, if nothing else, are highly social animals. Modern
primatology therefore promises to serve as the focus of some
of the most serious intellectual challenges of behavioral 
ecology.
Modern primates can be classified into four groups:
• The prosimians, which include lemurs, lorises, tarsiers,
and bushbabies;