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

PRIMATE
HERITAGE
10

---

instead, encompassing all aspects of their anatomy and
behavior, a definition constructed from universal or near-
universal characteristics is possible, says Martin.
“Primates are typically arboreal inhabitants of tropical and
sub-tropical forest ecosystems,” begins Martin’s definition. 
It goes on to describe features of hand and foot anatomy,
overall style of locomotion, visual abilities, intelligence,
aspects of reproductive anatomy, life-history factors (such as
longevity and reproductive strategy), and dental architec-
ture. The definition generally depicts species that have a
rather special niche in the world. The University of Sussex
anthropologist Alison Jolly recently noted, “If there is an
essence of being a primate, it is the progressive evolution of
intelligence as a way of life.”
Some of the key components of Martin’s definition are
described below.
Primate hands and feet have the ability to grasp and are
therefore equipped with opposable thumbs and opposable
great toes. Humans are an exception, as the human foot has
Definition of primate
Although humans have clearly departed from our primate
roots in colonizing so broad a range of habitats, many of 
the characteristics that we often envision as separating us
from other primatesasuch as habitual upright walking, great 
intelligence, and more complex forms of social organization
and behavior socialityaare actually extensions of, rather
than discontinuities with, what it means to be a primate. We
should therefore ask, What is it to be a primate?
Surprisingly, this question, which essentially asks for a
definition of “primate,” has proved difficult to answer con-
cisely. “It has, in fact, been a common theme throughout 
the literature on primate evolution that primates lack any
clear-cut diagnostic features of the kind found in other 
species of placental mammals,” notes Robert Martin, of the
Field Museum, Chicago. The difficulty, he suggests, stems
from an overemphasis on “skeletal features identifiable in
the fossil record.” If one looks at living primate species
10: Primate Heritage