Chapter 6: Biology in the Present: The Other Living Primates
Chapter Outlines
- What Is a Primate?
- History of classification of the order
- Linnaeus first described the order Primates for classification purposes.
- As identified by Le Gros Clark, primates have the following traits:
- Primates are adapted to life in the trees (arboreal adaptation).
- Primates eat a variety of foods (dietary plasticity).
- Primates invest a lot in a few offspring (parental investment).
- Arboreal Adaptation: Primates Live in Trees and Are Good at It
- Primates have a unique combination of specific arboreal adaptations.
- Primates Have a Versatile Skeletal Structure
- Clavicle acts as a strut to keep upper limbs to sides of body.
- Ulna and radius rotate forearm.
- Phalanges allow hand and foot dexterity.
- Opposable thumb (or big toe) allows digit to touch other fingers.
- Primates have a powerful precision grip.
- Primates have a distinctive spinal column with five vertebral types.
- Primates Have an Enhanced Sense of Touch
- The ends of fingers and toes are sensitive and allow for maximum information from environment.
- Primates Have an Enhanced Sense of Vision
- Eyes are rotated to the front of the head with overlapping fields of vision.
- Most primates see in color.
- Primates Have a Reduced Reliance on Senses of Smell and Hearing
- Most higher primates have lost the naked rhinarium (wet nose).
- Some prosimians retain the rhinarium.
- Smell is a secondary sense in most primates.
- Dietary PlasticityPrimates Eat a Highly Varied Diet, and Their Teeth Reflect This Adaptive Versatility
- Primates Have Retained Primitive Characteristics in Their Teeth
- Dental traits in four functionally distinct tooth types
- Primates Have a Reduced Number of Teeth
- Dental formula records number of teeth in one jaw quadrant.
- 2/1/2/3 is the formula for Old World monkeys and apes.
- 2/1/3/3 is the formula for New World monkeys.
- Primates Have Evolved Different Dental Specializations and Functional Emphases
- Premolars and molars used for grinding.
- Molars have different numbers of cusps.
- Bilophodont (two lobes).
- Y-5 (cusps in the shape of a “Y”).
- Canine-premolar honing complex slices food.
- Enamel thickness varies across order.
- Parental InvestmentPrimate Parents Provide Prolonged Care for Fewer, but Smarter, More Socially Complex, and Longer-Lived Offspring
- Female primates give birth to fewer offspring than other mammals.
- Investment in offspring is high.
- Development period is longer, especially in apes.
- Development period is related to larger brain size in primates.
- Humans have the largest brain for body size.
- What Are the Kinds of Primates?
- Over two hundred species with great physical and behavioral diversity
- Differences have occurred through evolution.
- Living primates provide models for understanding evolutionary past.
- Ad Hominin? Genetic vs. Anatomical Classification
- DNA analysis demonstrates humans, gorillas, chimpanzees and bonobos are more closely related than each is to orangutans.
- Chimpanzees and humans are more closely related than either is to gorillas.
- DNA analyses (genetic classification) provide a different window to the relationships between primates from anatomical classification, which provides insight into daptations. This book uses anatomical classification.
- Prosimians: The Lesser Primates
- Among oldest living primates
- Developed sense of smell
- Combination of nails and claws with less dexterity than other primates
- Geographic range: Madagascar and Southeast Asia
- Tarsiers share some traits with prosimians and anthropoids.
- Anthropoids: The Higher Primates
- Old World monkeys (catarrhines)
- Nostrils separated by a septum that points downward.
- Most diverse and most successful nonhuman primates
- Tough sitting pads on the rear (ischial callosities)
- Inhabit terrestrial and arboreal habitats in Africa and Asia
- Two subfamilies: cercophithecoids and colobines
- Baboons, macaques, mandrills, colobus
- New World Monkeys (platyrrhines)
- Rounded nostrils separated by a septum
- Prehensile tail
- Inhabit arboreal habitats in Latin America
- One subfamily: ceboids
- Spider, squirrel, howler monkeys
- Hominoids
- Great Apes: orangutan, chimpanzee, bonobo, gorilla
- Sagittal crest in gorilla, orangutan
- Chimpanzees omnivorous
- Humans characterized by skeletal structure for bipedalism
- Lesser Apes: gibbon, siamang
- Skilled brachiators
- Primate Societies: Diverse, Complex, Long-Lasting
- Diversity of Primate Societies
- Social Behavior: Enhancing Survival and Reproduction
- Social signals establish and maintain social relationships.
- Primate societies are organized.
- Primates form long-term social relationships.
- Social behaviors in primates enhance survival and reproduction and are thought to be maintained by natural selection.
- Primate Residence Patterns
- Primates have a wide variety of residence patterns, divided according to the number of adult males and females present in the group.
- Primate Reproductive Strategies: Males’ Differ from Females’
- Males compete for access to females; this affects male body and canine size.
- Females compete with each other for resources to support young; this affects social behaviors.
- The Other Side of Competition: Cooperation in Primates
- Cooperative levels in primates are also high.
- Altruistic behaviors include alarm calls, grooming, food sharing and caregiving.
- Part of kin selection, or behaviors related to living with relatives who share genetic material
- Seen most in cercopithecoids and chimpanzees
- Getting Food: Everybody Needs It, but the Burden Is on Mom
- Food resources and the search for them occupy over 50 percent of a primate’s waking hours.
- Especially high are the nutritional needs of females with offspring.
- Quality, distribution, and availability all affect a female’s success at foraging.
- Acquiring Resources and Transmitting Knowledge: Got Culture?
- Notion of nonhuman primate culture can be controversial.
- Jane Goodall was the first to assert that chimpanzees possessed material culture.
- Now, other researchers have also seen behaviors related to the use and alteration of objects as a form of material culture.
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