Chapter Study Outline

1. What Is a Primate?

a. History of classification of the order

i. Linnaeus first described the order Primates for classification purposes.

ii. As identified by Le Gros Clark, primates have the following traits:

(1) Primates are adapted to life in the trees (arboreal adaptation).

(2) Primates eat a variety of foods (dietary plasticity).

(3) Primates invest a lot in a few offspring (parental investment).

b. Arboreal Adaptation: Primates Live in Trees and Are Good at It

i. Primates have a unique combination of specific arboreal adaptations.

ii. Primates Have a Versatile Skeletal Structure

(1) Clavicle acts as a strut to keep upper limbs to sides of body.

(2) Ulna and radius rotate forearm.

(3) Phalanges allow hand and foot dexterity.

(4) Opposable thumb (or big toe) allows digit to touch otherfingers.

(5) Primates have a powerful precision grip.

(6) Primates have a distinctive spinal column with five vertebraltypes.

iii. Primates Have an Enhanced Sense of Touch

(1) The ends of fingers and toes are sensitive and allow for maximum information from environment.

iv. Primates Have an Enhanced Sense of Vision

(1) Eyes are rotated to the front of the head with overlapping fields of vision.

(2) Most primates see in color.

v. Primates Have a Reduced Reliance on Senses of Smell and Hearing

(1) Most higher primates have lost the naked rhinarium (wet nose).

(2) Some prosimians retain the rhinarium.

(3) Smell is a secondary sense in most primates.

c. Dietary Plasticity—Primates Eat a Highly Varied Diet, and Their Teeth Reflect This Adaptive Versatility

i. Primates Have Retained Primitive Characteristics in Their Teeth

(1) Dental traits in four functionally distinct tooth types

ii. Primates Have a Reduced Number of Teeth

(1) Dental formula records number of teeth in one jaw quadrant.

(2) 2/1/2/3 is the formula for Old World monkeys and apes.

(3) 2/1/3/3 is the formula for New World monkeys.

iii. Primates Have Evolved Different Dental Specializations and Functional Emphases

(1) Premolars and molars used for grinding

(2) Molars have different numbers of cusps.

(a) Bilophodont (two lobes).

(b) Y-5 (cusps in the shape of a “Y”).

(3) Canine-premolar honing complex slices food.

(4) Enamel thickness varies across order.

d. Parental Investment—Primate Parents Provide Prolonged Care for Fewer, but Smarter, More Socially Complex, and Longer-Lived Offspring

i. Female primates give birth to fewer offspring than other mammals.

ii. Investment in offspring is high.

iii. Development period is longer, especially in apes.

iv. Development period is related to larger brain size in primates.

v. Humans have the largest brain for body size.

2. What Are the Kinds of Primates?

a. Over two hundred species with great physical and behavioral diversity

i. Differences have occurred through evolution.

ii. Living primates provide models for understanding evolutionary past.

b. Ad Hominin? Genetic vs. Anatomical Classification

i. DNA analysis demonstrates that humans, gorillas, chimpanzees, and bonobos are more closely related than each is to orangutans.

ii. Chimpanzees and humans are more closely related than either is to gorillas.

iii. DNA analyses (genetic classification) provide a different window to the relationships between primates from anatomical classification, which provides insight into adaptations. This book uses anatomical classification.

c. Prosimians: The Lesser Primates

i. Among oldest living primates

ii. Developed sense of smell

iii. Combination of nails and claws with less dexterity than other primates

iv. Geographic range: Madagascar and Southeast Asia

v. Tarsiers share some traits with prosimians and anthropoids.

d. Anthropoids: The Higher Primates

i. Old World monkeys (catarrhines)

(1) Nostrils separated by a septum that points downward.

(2) Most diverse and most successful nonhuman primates

(3) Tough sitting pads on the rear (ischial callosities)

(4) Inhabit terrestrial and arboreal habitats in Africa and Asia

(5) Two subfamilies: cercophithecoids and colobines

(6) Baboons, macaques, mandrills, colobus

ii. New World Monkeys (platyrrhines)

(1) Rounded nostrils separated by a septum

(2) Prehensile tail

(3) Inhabit arboreal habitats in Latin America

(4) One subfamily: ceboids

(5) Spider, squirrel, howler monkeys

iii. Hominoids

(1) Great Apes: orangutan, chimpanzee, bonobo, gorilla

(a) Sagittal crest in gorilla, orangutan

(b) Chimpanzees omnivorous

(c) Humans characterized by skeletal structure for bipedalism

(2) Lesser Apes: gibbon, siamang

(a) Skilled brachiators