The Human Strategy

Description

The Human Strategy brings a unique and accessible evolutionary approach to the study of human anatomy. Bridging the disciplines of anthropology and biology, it acknowledges that human beings are vertebrates, mammals, and primates, and that the anatomical systems of the human body reflect adaptations from each of these levels of classification. John H. Langdon identifies the significance of those traits that make humans distinct from other vertebrates, exploring adaptations to the musculoskeletal, nervous, and reproductive systems and to systems of homeostasis. He addresses the question: "What functions are represented in the body structure and what history lies behind them?" Framing the answers in terms of physiological goals, functional adaptation, and evolutionary contingency, he covers both soft- and hard-tissue systems. Langdon considers how behavioral changes in our ancestors--bipedalism and a changing diet that incorporated meat--relate to anatomical changes in nearly every organ system and contributed to expansion of the brain, a higher energy budget, and a prolongation of life history.
Integrating the most recent research in the field, The Human Strategy features more than 250 clear and well-labeled illustrations that explain anatomical systems and processes. It includes tables that detail the differences between the major classes of vertebrates, helping students to put evolutionary variations among species in context. A comprehensive glossary and an extensive bibliography are also provided. Ideal for upper-level undergraduate and graduate courses in human evolutionary anatomy, The Human Strategy can also be used in human anatomy and human evolution courses. Taking a more complete look at the human body in an evolutionary sense than any other existing text--and demonstrating that the human present is best understood in terms of our past--this volume serves as an excellent starting point for discussion, critical thinking, and further research.

Table of Contents

List of Tables
Preface
PART I. INTRODUCTION
1. EVOLUTION AND ADAPTATION
What Is Evolution?
The Theory of Evolution
The Evidence for Evolution
Darwinism: Evolution by Natural Selection
Natural Selection
Evidence for Natural Selection
The Origin of Heritable Variation
How Variation Takes Form
Differences in Degree of Development
Differences in Direction of Development
The Limits of Natural Selection
Sexual Selection
Adaptationism: An Evolutionary Perspective
Other Paths to Adaptation
Important Evolutionary Concepts
2. A PLACE IN NATURE: HUMANS IN AN EVOLVING WORLD
A Place in Time
A Place in Life: Biological Classification
Comparative Background of the Human Species
Kingdom Animalia
Phylum Chordata
Subphylum Vertebrata
Tetrapods
Class Mammalia
Order Primates
Family Hominidae
The Emergence of Humans
PART II. MUSCULOSKELETAL SYSTEM
3. BONES, JOINTS, AND MUSCLES
Stresses and Strains
Cartilage
Bone
Development and Growth of Bone
Remodeling of Bone
Adaptations of Mammalian Bone
Ligament and Tendon
Joints
Accessory and Conjunct Motions
Muscle
Concepts of Functional Design
Reduction of Mass
Energetic Efficiency
4. THE SKULL
The Human Skull
Evolution of the Mammalian Skull
Origins of the Vertebrate Cranium
Mammalian Modifications of the Tetrapod Skull
Changes in the Primate Skull
The Primate Face
Orbital Convergence
Shortening the Face
The Cranial Vault
Browridges
Basicranial Flexion
Mechanics of Head Balance
Jaws
The Mandibular Symphysis and the Chin
The Australopithecine Chewing Complex
The Problem of Skeletal and Dental Reduction
5. TEETH
Tooth Development
Evolution of Vertebrate Teeth
Origins of Teeth
Mammalian Dental Adaptations
The Tribosphenic Molar
Hominin Teeth
Dental Formulae
Anterior Dentition
Posterior Dentition
The Dental Arcade and the Chewing Cycle
Hominin Enamel Adaptations
Dental Adaptations of the Neanderthals
Modern Trends and Variations in Human Dentition
6. THE SPINE
Stages in the Evolution of Vertebrate Body Design
Fish
Early Tetrapods
Mammals
Structure of the Human Vertebral Column
Intervertebral Joints
Regions of the Human Spine
Curvatures of the Spine
Fossil Evidence
Musculature of the Trunk
7. THE UPPER LIMB
Evolution of the Forelimb
The Origin of Tetrapod Limbs
The Mammalian Forelimb
Hominoid Adaptations
The Pectoral Girdle
The Elbow
Hands
Knuckle-Walking
Human Hands
Adaptations for Manipulation
Evolution of the Thumb
Fossil Tool-Makers?
8. THE LOWER LIMB
The Pelvis
Adaptations of the Hip Joint for Bipedalism
The Thigh
The Knee
Adaptations of the Knee for Bipedalism
The Leg
The Ankle and Foot
The Bones of the Foot
The Toes
Evolutionary Trends in Ankle and Foot Musculature
The Longitudinal Arch of the Foot
Conversion Mechanism of the Foot
Support for the Arch
Function of the Longitudinal Arch
Functional Variation in the Design of the Arch
9. THE HUMAN STRATEGY: BIPEDALISM
The Transition to Bipedalism
The Pelvis and Hip
The Knee
The Foot
The Australopithecine Body
After the Australopithecines
The Adaptive Significance of Bipedalism
Historical Speculations Concerning the Origin of Bipedalism
The Problem with Cultural Models
Reconstructing the Transition
PART III. THE NERVOUS SYSTEM
10. ORGANIZATION OF THE BRAIN
Initial Development of Nervous System
General Anatomy of the Brain
The Brainstem
The Forebrain
Diencephalon
Cerebrum
Functional Organization of the Brain
Specific and Nonspecific Projections
Consciousness
Functional Localization
Somatotopic Organization
Phylogenetic Layering
The Motor System
Decussation
Functional Lateralization
Language and Lateralization
The Evolution of Language and Lateralization
Lateralization in Primates
Evidence of Language in Nonhuman Primates
Fossil Evidence for Language
Integration with Other Systems
The Neuroendocrine System
The Autonomic Nerves
The Neuroendocrine Axis
Neuroendocrine Integration: The Stress Response
Integration with the Immune System
Integration with Consciousness: The Limbic System
Emotions
The Reward System
Memory
11. THE HUMAN STRATEGY: BRAIN SIZE
Comparing Brains
The Relation of Brain and Body Size
Brain Size and Function
The Rate of Hominin Brain Evolution
Selecting for Brain Size
The Social Model
Dietary Models
Metabolic Needs
Environmental Models
Overcoming Constraints
Selecting for Reorganization and New Abilities
Developmental Possibilities
Qualitative Differences in Function
12. THE SPECIAL SENSES
Olfaction
Central Pathways
The Evolution of Smell
The Vomeronasal Organ
Taste
Vision
Frontally Directed Vision
Photoreceptors and Color Vision
Evolution of Vision in the Brain
Equilibrium
Hearing
The Outer and Middle Ears
The Evolution of the Ear
PART IV. SYSTEMS OF HOMEOSTASIS
13. SKIN
The Anatomy of Skin
The Epidermis
The Dermis
The Hypodermis
Differences among Vertebrates
Getting a Grip: Fingerprints and Nails
Friction Pads and Fingerprints
Nails
Hair
Hair Reduction
Glands of the Skin
Apocrine Glands
Eccrine Glands
Sweat and Hair Reduction as a Human Strategy for Thermoregulation
A Problem of Fat
Fat as Insulation
Fat Is an Adaptation for the Brain
Explaining Human Skin Pigmentation
Melanin and Photoprotection
The Vitamin D Hypothesis
Other Hypotheses of Human Pigmentation
More Pigments
Hair and Eye Color
Melanin in Other Tissues
Genetics of Skin Pigmentation
14. DIGESTION AND DIET
A Natural Diet
The Digestive System
The Coelom and the Peritoneum
Tissue Structure of the Alimentary Canal
Organs of the Digestive Tract
The Start of the Canal
Esophagus
Stomach
Small Intestine
Accessory Glands
Colon
Reconstructing the Diet of Early Hominins
The Evidence of Dental Anatomy
The Evidence of Dental Microwear
Bone Composition and Diet
Archaeological Evidence of Meat Consumption
And Other Evidence. . .
Later Hominins
A Backward Look from the Present
Modern Hunter-Gatherer Diet
Feeding the Brain
Anatomical Adaptations
Frugivory, Carnivory, Omnivory
Recent Changes in Diet and Health
15. RESPIRATION
Evolution of Vertebrate Breathing
The Problem of Gas Exchange and Transport
Gills
Lungs and Swim Bladders
Breathing in Simple Tetrapods
Breathing in Mammals
Mechanics of Human Respiration
Functional Specializations of the Human Respiratory Tract
The Nasal Passages
The Pharynx
The Larynx
The Evolution of Speech
Climatic Adaptations
16. CIRCULATION
The Heart
The Chambered Heart
Structure and Function of the Human Heart
Evolution of Vertebrate Circulation
Circulation through Gills
Circulation through Lungs
Human Ontogeny Recapitulating Phylogeny
The Fetal Circulation Pattern
Changes at Birth
Circulation and Thermoregulation
Countercurrent Exchanges: Maintaining a Temperature Differential
Cooling the Body: Regulating Cutaneous Blood Flow
Cooling the Brain
17. EXCRETION
Evolution of the Vertebrate Kidney
The Vertebrate Nephron
Vertebrate Strategies
Kidneys of Simple Vertebrates
The Mammalian Kidney
The Concentration of Urine
Human Water Balance
18. THE HUMAN STRATEGY: ENERGY FLOW, HOMEOSTASIS, AND ENDURANCE
Limitations on Energy Processing
Endurance Requires Energy
Energy and Oxygen Consumption
Managing Heat
The Significance of Body Size and Form
Body Form and Climate Adaptation
The Human Strategy
PART V. REPRODUCTION
19. REPRODUCTION
The Origin of Sexual Reproduction
Gametes and the Basis of Sexual Selection
Dimorphism and Secondary Sexual Characteristics
Vertebrate Reproductive Strategies
Mammalian Strategies
Menstruation
The Placenta
Labor and Delivery
Labor: A Positive Feedback Mechanism
The Anatomy of Delivery
The Evolution of Birth
Lactation and the Breast
The Composition of Milk
Breasts and the Female Figure
Breasts as Erotic Attractors
Breasts as Advertisements
Breasts as Deceitful Advertisements
The Problem of Gender Recognition
20. SEX AND HUMAN EVOLUTION
Sexuality and Mating among the Apes
Two Adaptationist Models
The Pair-Bond Model
The Promiscuity Model
Contrasting the Models
Sexual Selection in the Human Species
Sexual Dimorphism in Body Size
Evidence for Sexual Selection of Men
Sexual Selection and Genital Size
Sperm Competition
Evidence for Sexual Selection among Women
Sexual Selection and Contemporary Mate Selection
Women: Choosing Status
Men: Choosing Reproductive Potential
Support for the Pair-Bond Model
Human Sexual Behavior
The Problem of Estrus
Is Ovulation Concealed?
The Pleasure of Sex
The Obscuring of Estrus: Support for the Promiscuity Model?
Human Mating Systems Are Flexible
Conclusions
21. THE HUMAN STRATEGY: LIFE HISTORY
The r and K Strategies
Trends
Human Life History
Stages of Life History
Fetal Life
Infancy and Nursing
Juvenile Life and Childhood
Subadults and Maturity
Postreproductive Life
Longevity and Evolution of the Modern Life Span
Dental Maturation in Early Hominins
Foraging, Energy, and Society
Glossary
Bibliography
Index