68 CHAPTER 3 | Living Primatesis that an emphasis on human origins in primatology meant
that Old World species were favored by researchers. The sec-
ond is that nearly all New World species are arboreal, which
makes it more difficult for researchers to observe them. In
recent decades, however, primatologists have conducted
numerous long-range field studies on a variety of species.
For example, anthropologist Karen Strier has studied
the woolly spider monkey, or muriqui, in the state of Minas
Gerais, Brazil, for close to three decades. Her field studies
progressed from examining muriqui diet, social structure,
and demographics (population characteristics such as the
number of individuals of each age and sex) to tracking
the reproductive cycles and health of these large, peace-
ful forest dwellers. She pioneered a noninvasive method
to measure reproductive hormone levels and the presence
of parasites through analysis of the feces of individual ani-
mals. Her fieldwork included waiting to catch feces (in a
gloved hand) the moment it was dropping from the trees
or quickly retrieving it from the ground. Through analysis
of these samples, Strier was able to document correlations
between diet and fertility.
Strier also documented a reduced parasite load in
muriquis that consumed certain plants—apparently for
their medicinal/therapeutic value. Amazonian peoples
have been known to use some of these plants for the same
reason. As these human populations become increasingly
removed from their traditional lifeways due to globaliza-
tion and modernization, the muriqui may become a valu-
able source to reclaim knowledge of the forest. According
to Strier, “While traditional peoples of the Amazon have
survived long enough to impart some of their knowledge of
forest plants, the indigenous human societies of the Atlantic
forest are long gone. The muriqui and
other monkeys may provide humans
with their best guides to the for-
est’s medicinal values.”^4
Field studies like Strier’s
not only have contributed
to our understanding of
the behavior and biology
of New World monkeys
but have also played a ma-
jor role in bringing back
a number of species from
the brink of extinction.
New World monkeys—
unlike Old World mon-
keys, apes, and humans—
possess a 2-1-3-3 dental
formula (three, rather than
two, premolars on eachNew World Monkeys
New World monkeys live in tropical forests of South and
Central America. In outward body plan they closely re-
semble Old World monkeys, except that New World mon-
keys are characterized by flat noses with widely separated,
outward-flaring nostrils. Their infraorder name platyr-
rhine (from the Greek for “flat-nosed”) comes from this
characteristic. There are five different families of New
World monkeys, and they range in size from less than a
pound to over 30 pounds.
There are two reasons why New World monkeys have
not been studied as extensively as other primates. The firstGrasping hands and three-dimensional vision enable primates like
this South American monkey to lead an active life in the trees. In
some New World monkey species, a grasping or prehensile tail makes
tree life even easier. The naked skin on the underside of the tail re-
sembles the sensitive skin found at the tips of our fingers and is even
covered with whorls like fingerprints. This sensory skin allows New
World monkeys to use their tails as a fifth limb.© Ingo Arndt/Minden Pictures
demographics Population characteristics such as the number
of individuals of each age and sex.Atlantic
Pacific Ocean OceanVENEZUELABOLIVIA Minas
PARAGUAY GeriasARGENTINAPERUCOLOMBIAURUGUAYGUYANA
SURINAME
FRENCH
GUIANABRAZILCHILE(^4) Strier, K. (1993, March). Menu for a monkey. Natural History, 42.