Evolution And History

58 CHAPTER 3 | Living Primates

Suborder Infraorder Superfamily (family) Location

I.

Prosimii

(lower primates)

Lemuriformes

Lorisiformes

Lemuroidea (lemurs, indriids,

and aye-ayes)

Lorisoidea (lorises)

Tarsioidea (tarsiers)

Madagascar

Asia and Africa

Asia

Anthropoidea

(higher primates)

Platyrrhini (New World

monkeys)

Catarrhini

Ceboidea

Cercopithecoidea (Old World monkeys)

Hominoidea (apes and humans)

Tropical Americas

Africa and Asia

Africa and Asia (humans worldwide)

II.

Strepsirhini Lemuriformes

Lorisiformes

Lemuroidea (lemurs, indriids,

and aye-ayes)

Lorisoidea (lorises)

Madagascar

Asia and Africa

Haplorhini Tarsiiformes

Platyrrhini (New World

monkeys)

Catarrhini

Tarsioidea (tarsiers)

Ceboidea

Cercopithecoidea (Old World monkeys)

Hominoidea (apes and humans)

Asia

Tropical Americas

Africa and Asia

Africa and Asia (humans worldwide)

researchers to establish a clade, a taxonomic grouping that

contains a single common ancestor and all of its descendants.

Genetic analyses allow for precise quantification, but it is not

always clear what the numbers mean (recall the Original

Study from Chapter 2). When dealing with fossil specimens,

paleoanthropologists begin their analyses by comparing the

specific shape and size of the bones with which they work.

The Linnaean system divides primates into two sub-

orders: the Prosimii (from the Latin for “before mon-

keys”), which includes lemurs, lorises, and tarsiers, and

the Anthropoidea (from the Greek for “humanlike”),

which includes monkeys, apes, and humans. The prosim-

ians have also been called the lower primates because they

resemble the earliest fossil primates. On the whole, most

prosimians are cat-sized or smaller, although some larger

forms existed in the past. The prosimians also retain cer-

tain features common among nonprimate mammals that

are not retained by the anthropoids, such as claws and

moist, naked skin on their noses.

In Asia and Africa, all prosimians are nocturnal and ar-

boreal creatures—again, like the fossil primates. The isolated

but large island of Madagascar, off the coast of Africa, how-

ever, is home to a variety of diurnal ground-dwelling pros-

imians. In the rest of the world, the diurnal primates are all

anthropoids. This group is sometimes called the higher pri-

mates, because they appeared later in evolutionary history

and because of a lingering belief that the group including

humans was more “evolved.” From a contemporary biologi-

cal perspective, no species is more evolved than any other.

Molecular evidence led to the proposal of a new pri-

mate taxonomy (Table 3.1). A close genetic relationship

was discovered between the tarsiers—nocturnal tree

dwellers who resemble lemurs and lorises—and monkeys

to be redrawn, and scientists often disagree about these
categorical distinctions.
There are two hot spots in the classification of primates
where scientists argue for alternate taxonomies: one at the
level of dividing the primate order into two suborders and
the other at the level of the human family and subfamily.
In both cases, the older classificatory systems, dating back
to the time of Linnaeus, are based on shared visible physi-
cal characteristics. By contrast, the newer taxonomic sys-
tems depend upon genetic analyses. Molecular evidence
has confirmed the close relationship between humans and
other primates, but genetic comparisons have also chal-
lenged evolutionary relationships that had been inferred
from physical characteristics. Laboratory methods involv-
ing genetic comparisons range from scanning species’ en-
tire genomes to comparing the precise sequences of base
pairs in DNA, RNA, or amino acids in proteins.
Both genetic and morphological (body form and struc-
ture) data are useful. Biologists refer to the overall similarity
of body plans within taxonomic groupings as a grade. The
examination of shared sequences of DNA and RNA allows

grade A general level of biological organization seen among

a group of species; useful for constructing evolutionary

relationships.

clade A taxonomic grouping that contains a single common

ancestor and all of its descendants.

Prosimii A suborder of the primates that includes lemurs,

lorises, and tarsiers.

Anthropoidea A suborder of the primates that includes New

World monkeys, Old World monkeys, and apes (including

humans).

Table 3.1 Two Alternative Taxonomies for the Primate Order: Differing Placement of Tarsiers