Chapte 1

A. Adaptation, Variation, and Change • Adaptation is the process by which organisms cope with environmental forces and stresses. o Human adaptation involves interaction between culture and biology. o For example, human adaptation to high altitudes (see Recap 1.1) uses both cultural and biological means: ▪ Technological adaptation (cultural) ▪ Genetic adaptation (biological) ▪ Long-term physiological adaptation (biological) ▪ Short-term physiological adaptation (biological) • Through time, social and cultural means of adaptation have become increasingly important for human groups. o Human groups have devised diverse ways of coping with a wide range of environments. o The rate of cultural adaptation has been rapidly accelerating during the last 10,000 years. ▪ Food production originated between 12,000 and 10,000 years ago, after millions of years during which foraging was the sole basis for human subsistence. ▪ The first civilizations developed between 6,000 and 5,000 B.P. (before the present). ▪ More recently, the spread of industrial production has profoundly affected human life. o Today’s global economy and means of communication link all people in the modern world system. Studying the impact of globalization presents new challenges for anthropology. B. Cultural Forces Shape Human Biology • Anthropology’s comparative, biocultural perspective recognizes that cultural forces constantly mold human biology. A biocultural perspective uses both biological and cultural approaches to understand an issue or problem. o Cultural traditions promote certain activities and abilities, discourage others, and set standards of physical well-being and attractiveness. o Cultural standards of attractiveness and propriety influence participation and achievement in sports (e.g., Brazilian body ideals for women disfavor the big, strong shoulders and firm bodies of female competitive swimmers). III. General Anthropology • The academic discipline of general anthropology in North America includes four main subdisciplines. o Sociocultural anthropology (cultural anthropology) focuses on societies of the present and recent past. o Anthropological archaeology reconstructs lifeways of ancient and more recent societies through analysis of material remains. o Biological anthropology studies human biological variation through time and across geographic space. o Linguistic anthropology examines language in its social and cultural contexts. • The origin of North American (four-field) anthropology can be traced to the nineteenth century. Early American anthropologists were especially concerned with exploring the origins and diversity of Native American groups, studying their customs, social life, language, and physical traits. • The four subdisciplines share a similar goal of exploring variation in time and space to improve the understanding of the basics of human biology, society, and culture—and their interrelations. o Any conclusions about “human nature” must be pursued with a comparative, crosscultural approach. IV. The Subdisciplines of Anthropology A. Cultural Anthropology • Cultural anthropology combines ethnography and ethnology to study human societies and cultures for the purpose of describing, analyzing, interpreting, and explaining social and cultural similarities and differences. o Ethnography consists of fieldwork in a particular cultural setting. ▪ During ethnographic fieldwork, anthropologists collect data that are then organized, analyzed, and interpreted to produce an account (a book, an article, or a film) of a particular community, society, or culture. ▪ Ethnographic fieldwork has traditionally tended to emphasize local behavior, beliefs, customs, social life, economic activities, politics, and religion. Today, anthropologists also explore the impact of external forces and events on communities. ▪ Anthropology differs from other social sciences in its focus on local (often poor and powerless) people rather than the policy and decision making ofelites. ▪ Since cultures are not isolated, ethnographers must investigate the linkages among local, regional, national, global systems of politics, economics, and information that affect people’s lives across the world. o Ethnology examines, interprets, analyzes, and compares the results of ethnography. Ethnology compares and contrasts the particular data gathered in different societies to make generalizations about society and culture. ▪ Ethnology uses ethnographic data (and findings from the other subfields) to identify and explain cultural differences and similarities, to test hypotheses, and to form theories that enhance our understanding of social and cultural systems.B. Anthropological Archaeology • Anthropological archaeology (or archaeology) reconstructs, describes, and interprets human behavior and cultural patterns through material remains. o The material remains of a culture include artifacts (potsherds, jewelry, and tools), garbage, burials, wild and domesticated grains, and the remains of structures. These remains help archaeologists reconstruct patterns of production, trade, and consumption. o Archaeologists use paleoecology (the study of ecosystems of the past) to examine the intersections of nature and human culture and how they influence each other. ▪ Ecology is the study of interrelations among living things in an environment. o Archaeologists use excavation to reconstruct behavior patterns and lifestyles of the past, as well as changes over time in a given area. o Archaeology is not restricted to prehistoric societies. ▪ Studying sunken ships off the Florida coast, underwater archaeologists have verified the living conditions on the vessels that brought ancestral African Americans to the New World as enslaved people. ▪ William Rathje’s “garbology” project in Tucson, Arizona, drew attention to the anthropological information to be discovered in modern landfills. C. Biological Anthropology • Biological anthropology investigates human biological diversity through time and as it exists today. o There are five specialties within biological anthropology: ▪ Paleoanthropology: the study of human evolution as revealed by the fossil record▪ Human genetics ▪ Human growth and development ▪ Human biological plasticity: the living body’s ability to change as it copes with environmental conditions, such as heat, cold, and altitude ▪ Primatology: the study of monkeys, apes, and other nonhuman primates o A commonality among all five specialties is an interest in biological variation among humans, including their ancestors and closest animal relatives (monkeys and apes). o These varied interests link biological anthropology to biology, zoology, geology, anatomy, physiology, medicine, and public health. D. Linguistic Anthropology • Linguistic anthropology is the study of language in its social and cultural context throughout the world and over time. o Some linguistic anthropologists investigate universal features of language that may be linked to uniformities in the human brain. o Linguistic anthropologists have studied linguistic differences to examine the relationship of language structure and thought patterns in different cultures. o Historical linguists reconstruct ancient languages and study linguistic variation through time. o Sociolinguistics investigates relationships between social and linguistic variation. V. Applied Anthropology • Applied anthropology refers to the application of anthropological data, perspectives, theory, and methods to identify, assess, and solve social problems. • Applied anthropologists come from all four subfields of anthropology. o Applied medical anthropologists consider the sociocultural and biological contexts and implications of disease and illness. o Applied archeology, or public archeology, includes work in cultural resource management (CRM), public educational programs, and historic preservation. ▪ CRM involves deciding what needs saving when entire archaeological sites cannot be saved. VI. Anthropology and Other Academic Fields • Anthropology is distinguished among other fields of study by its holism, which uniquely blends biological, social, cultural, linguistic, historical, and contemporary perspectives. o Anthropology is a science, in that it is a systematic field of study that usesexperiment, observation, and deduction to produce reliable explanations of human cultural and biological phenomena. o Anthropology also has strong links to the humanities in that it encompasses the study and cross-cultural comparison of languages, texts, philosophies, arts, music, performances, and other forms of creative expression. A. Cultural Anthropology and Sociology • Like anthropology, sociology studies society, including human social behavior, social relations, and social organization. • Key differences between the two disciplines are reflected in the types of society that each has traditionally studied and the methods used by each. o Sociologists typically have studied contemporary, Western, industrial societies, whereas anthropologists have focused on nonindustrial and non-Western societies. o Sociologists have tended to employ surveys and other quantitative methods, which apply sampling and statistical techniques. As anthropologists focus more on modern nations, they often employ similar tools. o In ethnographic study, the anthropologist takes part in the events that are being observed, described, and analyzed. • In many areas and with many topics, anthropology and sociology are converging. B. Anthropology and Psychology • Psychological anthropology has contributed a cross-cultural perspective to concepts developed in psychology, both on psychoanalytic propositions and on issues of development and cognition. • One application is in the study of culturally-specific syndromes: patterns of unusual, aberrant, or abnormal behavior confined to a single culture or a group of related cultures. o Twenty-first century psychological anthropology must recognize how local indigenous patterns interact with the forces of globalization. VII. The Scientific Method • As a science, anthropology aims for reliable explanations that predict future occurrences. A. Theories, Associations, and Explanations • Scientists strive to improve our understanding of the world by hypothesis testing. o A hypothesis is a suggested but as of yet unverified explanationA hypothesis must be tested to confirm the explanation is good. o An explanation shows how and why one variable causes or is closely associated with another variable that one wants to explain. • Theories provide explanations for associations. o An association is an observed relationship between two or more measured variables. o A theory is a set of ideas formulated to explain something. • A law is a generalization that applies to and explains all instances of an association. o Associations are explored to help illustrate a general principle—like the association between the state of water and the air temperature. o In the social sciences, associations are usually stated probabilistically: two or more variables tend to be related in a predictable way, but there are exceptions. B. Case Study: Explaining the Postpartum Taboo • Theories suggest patterns, connections, and relationships that may be confirmed by new research. o The study of the connection between the postpartum sex taboo (dependent variable) and a low-protein diet (predictor variable), suggested that the taboo is advantageous to the health of babies with low-protein diets because as a result of the taboo they breastfeed longer. • In hypothesis testing, the relevant variables should be clearly defined and measured reliably; and results should be evaluated with legitimate statistical methods. o A common mistake is citing cases that confirm a hypothesis while ignoring those that do not do so. o The best procedure is random selection of cases from a wide sample. C. The Value, and Limitations, of Science • Science isn’t the only way of understanding the world; cultural anthropology often utilizes approaches that are more interpretive, qualitative, and humanistic. VIII. Features Focus on Globalization: World Events • The study of global–local linkages is an important part of modern anthropology and is facilitated by mass media, which draw people together to participate in world events. • Some examples of world events that have generated global interest include the Apollo 11 moon landing in 1969; Prince William and Catherine Middleton’s wedding in 2011;and many international sports competitions such as the Olympics and World Cup soccer. • Although American baseball has little worldwide mass appeal, it is an ethnically diverse sport that shows us a multiethnic world in miniature.

Chapter 2

CHAPTER OUTLINE I. Introduction: Understanding Ourselves • Americans are enculturated to view themselves as individuals. In contrast, this chapter views people as members of groups first and individuals second. o For example, different national cultures have their own standards for appropriate physical displays of affection. Consequently, the bodily interaction of a Brazilian and an American might lead one to construct the other as either cold or overbearing. o Thinking that there is only one right or natural way of doing such things is an example of ethnocentrism. II. What Is Culture? • Sir Edward Tylor defined culture as, “that complex whole which includes knowledge, belief, arts, morals, law, custom, and any other capabilities and habits acquired by man as a member of society.” • Enculturation is the process by which a child learns his or her culture. A. Culture Is Learned • Cultural learning is unique to humans. • Cultural learning is the accumulation of knowledge about experiences and information not perceived directly by the organism but transmitted to it through symbols. o Symbols are signs that have no necessary or natural connection with the things they signify or for which they stand. o Anthropologist Clifford Geertz described cultures as sets of “control mechanisms—plans, recipes, rules, instructions” and likens them to computer programs that govern human behavior. • Culture is learned through direct instruction and observation, providing conscious and unconscious means for the acquisition of cultural knowledge. • Anthropologists agree that all human populations share the same capacity for culture. B. Culture Is SymbolicThe human ability to use symbols is the basis of culture. • A symbol is defined as something verbal or nonverbal within a particular language or culture that comes to stand for something else. o In addition to language, there is a rich array of nonverbal symbols. Flags are one example. • Other primates have demonstrated a rudimentary ability to use symbols, but only humans have elaborated cultural abilities such as to learn, to communicate, to store, to process, and to use symbols. C. Culture Is Shared • Culture is an attribute not of individuals per se but of individuals as members of groups. • The social transmission of culture tends to unify people by providing them with common experiences. • Such experiences in turn shape people’s values, memories, and expectations. D. Culture and Nature • Cultural habits, perceptions, and inventions mold human nature in many directions. • People’s culture and cultural changes affect the ways in which they perceive nature, human nature, and the natural world. E. Culture Is All-Encompassing • The anthropological concept of culture includes all aspects of human social life. • Everyone is “cultured,” not just wealthy people with elite educations. F. Culture Is Integrated • A culture is an integrated, patterned system: changes in one dimension of culture will likely generate changes in other dimensions. • Core values are sets of ideas, attitudes, symbols, and judgments that further integrate a particular culture and distinguish it from others. G. Culture Is Instrumental, Adaptive, and Maladaptive • Like other animals, humans adapt biologically; but culture is the main instrument of human adaptability and success. • People use culture to fulfill their needs. o These include basic biological needs for food, drink, shelter, comfort, and reproduction. o They also include psychological and emotional needs for such things as friendship, companionship, and approval. • Sometimes adaptive behavior that offers short-term benefits to particular individuals may harm the environment and threaten a group’s long-term survival, thus making certain cultural traits, patterns, and inventions ultimately maladaptive. III. Culture’s Evolutionary Basis • The human capacity for culture has an evolutionary basis that extends back at perhaps 3 million years. o Similarities between humans and apes are apparent in anatomy, brain structure, genetics, and biochemistry. o Humans are most closely related to chimpanzees and gorillas. ▪ Hominids: chimps and gorillas ▪ Hominins: a group that leads to humans but not to chimps and gorillas o Many human traits reflect the fact that the ancestors lived in trees, including grasping, manual dexterity, opposable thumbs, depth and color vision, a large brain, a substantial parental investment in limited offspring, sociality, and cooperation. o Manual dexterity and depth perception are essential in manipulating objects and making tools. o The ratio of brain size to body size among primates exceeds that of most mammals, as is the size of the brain’s outer layer, concerned with memory, association, and integration, permitting monkeys, apes, and humans to learn more. A. What We Share with Other Primates • Humans and other primates can modify learned behavior and social patterns instead. • The most studied form of ape toolmaking involves “termiting,” in which chimps make tools to probe termite hills. • The ability to aim and throw objects • Primate research shows that other primates, especially chimpanzees, are habitual hunters. B. How We Differ from Other Primates • Cooperation and sharing are much more characteristic of humans. • Human females lack a visible estrus cycle and have concealed ovulation, leading to more durable pair bonds, or marriage. • Marriage leads to exogamy, kinship groups, and lifelong ties with children.IV. Universality, Generality, and Particularity • Anthropologists distinguish among the universal, the generalized, and the particular in studying human diversity. o Cultural universals are certain biological, psychological, social, and cultural features that are found in every culture. o Cultural generalities include features that are common to several but not all human groups. o Cultural particularities are features that are unique to certain cultural traditions. A. Universals and Generalities • Biologically based universals include a long period of infant dependency, year-round sexuality, and a complex brain that enables people to use symbols, languages, and tools. • Social universals include life in groups and families of some kind. • Generalities occur in certain times and places, but not in all cultures. o The nuclear family is one cultural generality that is present in many but not all societies. o Cultural generalities may arise through cultural borrowing (diffusion), inheritance from a common cultural ancestor, or through domination, such as when a more powerful nation imposes its customs and procedures on another group. B. Particularity: Patterns of Culture • Practices that are unique to a single place, culture, or society are cultural particularities. • Cultures are integrated and patterned differently and display tremendous variation and diversity. V. Culture and the Individual • Individual human beings make up the system—meaning culture, society, social relations, or social structure—but are also constrained by its rules and the actions of others. o While cultural rules provide guidance, people use their culture actively and creatively; they have the ability to avoid, manipulate, subvert, and change the rules and patterns of their own cultures. o Culture is contested, and supposedly common symbols may have radically different meanings to different individuals and groups in the same culture. o Some anthropologists find it useful to distinguish between ideal culture, or the normative descriptions of a culture given by its people, and real culture, or behavior as observed by an anthropologist. o Culture may be described as having interrelated public and individual dimensions. o Contemporary anthropologists tend to view culture as a process in action, practice, and resistance, rather than as an entity transmitted across generations. ▪ Agency is the actions individuals take, both alone and in groups, in forming and transforming cultural identities. o Practice theory is an approach to culture that focuses on how varied individuals, through their ordinary and extraordinary actions and practices, manage to influence, create, and transform the world in which they live. A. Levels of Culture • National culture refers to the experiences, beliefs, learned behavior patterns, values, and institutions shared by citizens of the same nation. • International culture refers to cultural practices that extend beyond and across national boundaries. • Subcultures are identifiable cultural patterns and traditions associated with particular groups in the same complex society. B. Ethnocentrism, Cultural Relativism, and Human Rights • Ethnocentrism is the tendency to view one’s own culture as superior and to apply one’s own values in judging the behavior and beliefs of people raised in other cultures. o What may seem alien to one culture might appear normal, proper, and prized elsewhere. o The fact that cultural diversity calls ethnocentrism into question. • What happens when cultural practices, values, and rights come into conflict with human rights? o Some cultures in the Middle East and Africa have customs requiring female genital modification. Clitoridectomy and infibulation are two such practices. ▪ These procedures are traditional where practiced but are opposed by human rights advocates for infringing on the basic human right to control one’s body and sexuality. (Does circumcision of infants in the United States, and other male genital operations, fall into a similar category?) • The concept of cultural relativism asserts that behavior in one culture should not be judged by the standards of another culture. o Cultural relativism is not a moral position in anthropology but a methodological one; in order to understand a culture, one must try to understand how people in that culture see things. • The concept of human rights invokes a realm of justice and morality beyond andsuperior to countries, cultures, and religions; rights that are vested in the individual. • Cultural rights are vested not in individuals but in groups and include a group’s ability to preserve its cultural traditions. o Indigenous intellectual property rights (IPR) allow indigenous groups to control who may know and use their collective knowledge and its applications. • An understanding of cultural relativism and cultural rights does not preclude an anthropologist from making a judgment based on what he or she refers to as international standards of justice and morality. VI. Mechanisms of Cultural Change • Diffusion, defined as the spread of cultural traits through borrowing between cultures, has been a source of cultural change throughout human history. o Diffusion is direct, when two cultures trade, intermarry, or wage war on one another. o Diffusion is forced when one culture subjugates another and imposes its customs on the dominated group. o Diffusion is indirect when cultural practices or traits move from group A to group C via group B without any firsthand contact between groups A and C. • Acculturation is the exchange of cultural features that results when groups come into continuous firsthand contact. o Pidgin is an example of acculturation because it is a language form that develops by blending elements from different languages in order to facilitate communication between the populations in contact, such as in trade relationships. • Independent invention is the process by which humans innovate, creatively finding solutions to problems. o Cultural generalities are partly explained by the independent invention of similar responses to similar cultural and environmental circumstances. o The independent invention of agriculture in the Middle East and Mexico is one example. VII. Globalization: Its Meaning and Its Nature • Globalization encompasses a series of processes that work transnationally to promote change in a world in which nations and people are increasingly interlinked and mutually dependent. o The forces of globalization include international commerce and finance, travel and tourism, transnational migration, and the media—including the Internet and other high tech information flows. • The primary meaning of globalization—and the meaning on which this book focuses—is worldwide connectedness and linkages.o A second, political meaning has to do with efforts to create a global free market for goods and services. • The media play a key role in globalization. o Media spread information about products, events, lifestyles, and perceived benefits of globalization. o People increasingly live their lives across borders, maintaining connections with more than one nation-state. o Money, resources, and information are transmitted rapidly across vast distances. • The effects of globalization are broad and often unwelcome, representing threats to locals’ autonomy, identity, and livelihood.

Chapter 3

chapter 4

I. Introduction: Understanding Ourselves • Compared to other primates, humans are incredibly social. Social networking sites like Facebook, Twitter, and Instagram provide a particularly modern illustration, but the human body demonstrates that there has been a long evolutionary history of human sociality. • In particular, humans—unlike their primate relatives—require assistance during childbirth because of the way bipedalism has shaped the pelvis and how increased cranial capacity has molded the infant skull. o As a result, almost all human societies provide assistance to women during childbirth as the infant navigates the winding human birth canal. II. Research Methods in Archaeology and Biological Anthropology • Archaeology and biological anthropology are two of anthropology’s four subfields. o Archaeologists tend to study material culture; biological anthropologists tend to study biological remains. A. Multidisciplinary Approaches • Biological anthropologists and archaeologists collaborate with scientists from diverse fields in the study of sites, fossils, and artifacts. o Paleontologists study ancient life through the fossil record. o Palynology, the study of ancient plants through pollen samples, is used to shed light on a site’s environment at the time a given culture occupied it. o Bioarchaeologists examine human remains to reconstruct physical traits, health status, and diet. • Archaeologists can draw on microscopic evidence, such as fossil pollen, phytoliths (plant crystals), and starch grains, to gain a picture of what a site looked like originally. o Because phytoliths are inorganic and do not decay, they can reveal which plants were present at a given site even when no other plant remains survive. o Starch grains can also be recovered because they preserve well in humid, tropical locations where other organic remains usually decay. • Remote sensing, or the use of aerial and satellite images to locate sites on the ground, plays an important role in locating certain types of archaeological features, such as a system of ancient canals that would otherwise not be visible to the naked eye. o Remote sensing enabled archaeologists to discover and study ancient footpaths in Costa Rica around a volcano called Arenal (Sheets 2006). o Volcanic ash, sediment, and vegetation had hidden the paths, which were up to 2,500 years old. o The ancient trails showed up as thin red lines, reflecting the dense vegetation growing over them. • Originally developed for space applications, a technology known as LiDAR (light detection and ranging) is a remote sensing technique that uses lasers to map 3D surfaces and visualize landscapes. o LiDAR has enabled scientists to map more than 800 square miles (2,100 square kilometers) of the Maya Biosphere Reserve in the Petén region of Guatemala. B. Studying the Past • Fossils are remains, traces, or impressions of ancient life forms. • Teams of interdisciplinary scholars work to identify sites where fossils exist in order to compile the fossil record of human evolution. • Other materials from a site, such as pollen and soil samples, rock samples, and sediments, help provide valuable information and are used in dating techniques. C. Survey and Excavation • Archaeologists work in teams, adopting both local (e.g., excavation) and regional (e.g., survey) approaches. Systematic Survey • A systematic survey provides a regional perspective by gathering information on settlement patterns. • Surveying is one of the ways in which archaeologists locate sites that might be candidates for excavation in the future. • During a survey, the team records the location, size, and approximate age of the site. • Settlement patterns are important for making inferences regarding the prehistoric communities that lived in a given area, including population estimates and levels of social complexity. o Among hunter-gatherers and farmers, there are generally low numbers of people living in small campsites or hamlets, with little variation in architecture. o With increasing social complexity, population levels rise (that is, more people come to live in the same space) and a variety of sites exist along a settlement hierarchy—cities, towns, villages, and hamlets—with increased architectural variation among sites. Excavation • During excavation, scientists dig through layers of deposits that make up a site. Excavation complements regional survey data with more fine-grained data collected at the level of a specific site. • The layers or strata that make up a particular site help archaeologists establish a relative chronology for the material recovered. o The principle of superposition states that in an undisturbed sequence of strata, the oldest layer is on the bottom and each successive layer above is younger than the one below. o Artifacts from lower strata are thus older than artifacts from higher strata, and artifacts from the same strata are roughly the same age. • Nobody digs a site without a clear reason, because there are so many site possibilities and excavation is very expensive and labor-intensive. o Cultural resource management (CRM) is concerned with excavating sites that are threatened by modern development. o Most other sites are selected for excavation because they are well suited to address a series of specific research questions. • Before a site is excavated, it is first mapped and surface data is collected, so that the archaeologist can make an informed decision about where to dig. o A grid is drawn to represent and subdivide the site, after which equal-sized sections of the grid are marked off on the actual site. o The grid enables archaeologists to record the exact location of any artifact, fossil, or feature found at the site. • Digging can be done either according to arbitrary levels or by following the natural stratigraphy. o Using arbitrary levels is a faster but less refined method, during which important information can be lost. o Following the natural stratigraphy is a more labor-intensive but also more precise way of excavating a site, as each layer—natural or cultural—is peeled off one by one. • Archaeologists use a range of techniques to recover materials from an excavation. o All of the excavated soil is passed through screens to increase the likelihood that small and fragmented remains are recovered.o Flotation is used to recover carbonized and very small materials like fish bones and seeds. III. Kinds of Archaeology • Archaeologists pursue diverse research topics. o Experimental archaeologists try to replicate ancient techniques and processes like toolmaking under controlled conditions. o Historical archaeologists use written records as guides and supplements in their study of societies with written histories. ▪ Colonial archaeology is a type of historical archaeology that uses written records to locate and excavate postcontact sites in North and South America. o Classical archaeologists study the literate civilizations of the eastern region of the Old World, such as Greece, Rome, and Egypt. o Underwater archaeology is a growing field that investigates submerged sites, most often shipwrecks. • Archaeologists carry out cultural resource management and contract archaeology by applying their techniques of data gathering and analysis to manage sites that are threatened by development, public works, and road building. IV. Dating the Past • The archaeological record is not a representative sample of all the plants and animals that have ever lived. o Some species and body parts are better represented than others, for different reasons: their level of preservation, the sediment conditions in which they were initially buried, the chemical conditions of fossilization, and their placement in arid regions where they are more likely to be uncovered through erosion. o Taphonomy is the study of the processes that affect the remains of dead animals. o Paleontology is the study of ancient life through the fossil record; paleoanthropology studies ancient humans and their immediate ancestors. o Paleoanthropology and paleontology are both interested in establishing a chronology for the evolution of life. A. Relative Dating • Many dating methods depend upon stratigraphy, the study of earth sediments deposited in demarcated layers (strata). • Relative dating establishes a time frame in relation to other strata or materials. • When fossils are found within a given stratigraphic sequence, scientists know their dates relative to fossils in other strata. • Fluorine absorption analysis, another relative dating technique, was used to expose the Piltdown man hoax. B. Absolute Dating: Radiometric Techniques • Absolute dating techniques offer more precise and quantified dates rather than relative dates, although absolute dating may provide a range of dates instead of an exact date. • Radiometric techniques are based on known rates of radioactive decay in elements found in or around fossils. • Examples of radiometric techniques include 14C and potassium–argon (K/A) dating; thermoluminescence (TL); and electron spin resonance (ESR). o Because the half-life of 14C is short, this technique reliably dates specimens up to 40,000 years old; the 14C method can be used only for organic remains. o The half-life of potassium–argon (K/A) is far longer than that of 14C, so this method provides reliable dating for older specimens (more than 500,000 B.P.) rather than more recent ones; in contradistinction to 14C, potassium–argon (K/A) dating can be used only for inorganic substances like rocks and minerals. o TL and ESR dating provide alternate dating methods for fossils that cannot be dated by 14C or potassium–argon methods by measuring the electrons that are trapped in rocks and minerals associated with a fossil, then applying the date of the rock to the fossil. C. Absolute Dating: Dendrochronology • Dendrochronology, or tree-ring dating, is a method of absolute dating based on the study and comparison of patterns of tree-ring growth; this technique also provides information about climatic patterns in specific regions. • Charting ring patterns through time, scientists can compare wood from ancient buildings to known tree-ring chronologies, match the ring patterns, and determine—to the year— the age of the wood used by a historic or prehistoric builder. • Crossdating is the process of matching ring patterns among trees with visual and statistical techniques and assigning rings to specific calendar years. • Dendrochronology is limited to certain tree species that grow in a climate with marked seasons. D. Molecular Anthropology • Molecular anthropology studies genetic similarities and differences to assess evolutionary relationships among species.o The more similar the DNA, the more closely related the species. • Molecular studies are also used to estimate evolutionary distances between species. • Scientists also use DNA comparison to determine whether particular fossil hominin species were human ancestors. • Another use of molecular anthropology is to establish when ancient species lived and when they diverged from other species. o Differences in DNA arise from mutations—changes in genetic structure that are passed on through heredity. o Through time, more and more mutations occur, so that the DNA of descendants differs increasingly from the DNA of their ancestors. • Molecular anthropology is also used to reconstruct waves of human migration and settlement. o Analysis of haplogroups, a biological lineage defined by a specific cluster of genetic traits, has enabled molecular anthropologists to date a major wave of human migration out of Africa beginning around 70,000 years ago. V. Kinds of Biological Anthropology A. Bone Biology • Bone biology is the study of bone as a biological tissue, including its genetics, cell structure, growth, development, decay, and patterns of movement (biomechanics). • Paleopathology is the study of disease and injury in skeletons from archaeological sites. • Forensic anthropologists work in a legal context assisting coroners, medical examiners, and law enforcement agencies in recovering, analyzing, and identifying human remains and determining the cause of death. B. Anthropometry • Anthropometry is the measurement of human body parts and dimensions, including skeletal parts, and is used to study nutrition, growth, and development. C. Primatology • Primatology is a subfield of biological anthropology that is linked to paleoanthropology and sociocultural anthropology. o The most effective primate studies are done in natural settings. o Studies of primate social systems and behavior suggest hypotheses about what humans do and do not share with their nearest living relatives and their hominin ancestorsVI. Doing Anthropology Right and Wrong: Ethical Issues • Anthropologists must be aware of the ethical and legal contexts and value systems in which their work unfolds. o Many biological anthropologists and archaeologists work in foreign countries, frequently as members of multinational teams. o Researchers must communicate with officials and colleagues in the host country and negotiate the details of the research process (for example, where the research materials will be analyzed and stored). o Informed consent (agreement to take part in the research—after having been informed about its nature, procedures, and possible impacts) must be sought in order to ensure that no humans or animals are harmed or endangered by the research activities. • North American anthropologists working abroad should do the following: o Include host country colleagues in research planning and requests for funding. o Establish truly collaborative relationships with these colleagues and their institutions. o Include host country colleagues in dissemination of research results. o Ensure host country colleagues benefit from the research. A. Ownership Issues • Despite these efforts, ethical issues in anthropology continue to arise. o Lawsuits against museums by groups seeking repatriation of remains and artifacts are now common. o The Native American Graves Protection and Repatriation Act (NAGPRA) requires museums to return remains and artifacts to tribes that can prove “cultural affiliation.” • In 1996, a skeleton called “Kennewick Man” became the focus of a court case, as five Native American tribes considered the skeleton an ancestor and wanted it buried, whereas anthropologists wanted to study the skeleton, which is one of the oldest (between 8,500 and 9,500 years old) and best-preserved human remains ever discovered in North America. o The courts ruled in favor of the anthropologists, on the grounds that there was insufficient evidence to link the skeleton with any living group. o One result of the study of this skeleton, however, was the identification of a genetic connection to one of the tribes that claimed “the Ancient One” as their ancestor. o In 2016 President Obama signed an act directing the return of the remains to one of the five Native American nations living in the area where they had been found.B. The Code of Ethics • The American Anthropological Association’s Code of Ethics is a guide for anthropologists to help them fulfill their obligations and to prevent harm to their scholarly field, their research subjects, and the environment. o Anthropologists should be open and honest with all parties affected by research by informing them about the nature, procedures, purpose(s), potential impacts, and source(s) of support for the research. o Researchers should maintain proper relations between themselves and the host nations and communities in which they work. o It may be ethically justifiable to take a stand in order to shape actions and policies on issues.

chapter 5

I. Introduction: Understanding Ourselves • Although genes do determine some things—blood type, prevalence of sickle cell anemia, hemophilia—other aspects of human physiology are more plastic (changeable). • While many cultural interventions, especially medical ones, are generally viewed favorably, there are those who worry that people may be intervening too much with human biology. • All these concerns are related to the theory of evolution, the central organizing principle of modern biology. Evolution is also a fact. II. Evolution A. Natural History before Darwin • During the 18th century, many scholars became interested in biological diversity, human origins, and the human position within the classification of plants and animals (e.g., the first comprehensive and still influential taxonomy of plants and animals, by Carolus Linnaeus). • The commonly accepted explanation for the origin of species during the 18th century was creationism, which is the belief that biological similarities and differences originated at Creation and that characteristics of life forms are immutable. • The discovery of fossil remains of creatures clearly unknown to modern humans was and remains not accounted for within the terms of simple creationism. • Catastrophism arose as a modified version of creationism that posited divinely authored worldwide disasters that wiped out ancient species; presented new, divine events of species creation; and permitted the survival of some ancient species in isolated areas to explain the existence of fossil remains. • The alternative to creationism and catastrophism was transformism, which is better known as evolution. • Darwin was influenced by Charles Lyell’s principle of uniformitarianism. o Uniformitarianism is the belief that natural forces at work today also explain past events. o It further asserts that current geological structures are the result of long-term natural forces. o Darwin applied the theory of long-term transformation through natural forces to living things. When integrated into evolutionary theory, uniformitarianism cast doubt on whether the world was only 6,000 years old, as posited in creationism. o Darwin argued that all life forms are related and that the number of species has increased over time. B. Evolution: Theory and Fact • Darwin provided a theoretical framework for the understanding of evolution. o Natural selection was the principal mechanism that could explain changes in life forms. • Evolution is both a theory and a fact. • Evolution as a theory is a central organizing principle of modern biology and anthropology. o A theory is a set of logically connected ideas formulated to explain something. It suggests patterns, connections, and relationships that may be confirmed by further research. • The fact of evolution was known prior to Charles Darwin’s influential research and writing, but Charles Darwin contributed a theory of evolution through natural selection, explaining how evolution occurred. o Darwin posited natural selection as a single theory that could explain the origin of species, biological diversity, and similarities among related life forms, reaching this conclusion along with Wallace. o Natural selection is the gradual process by which the forms best suited to survive and reproduce in a particular environment do so in greater numbers than other members in the same population. ▪ For natural selection to work in a given population there must be variety within that population (as there always is) and competition for strategic resources. ▪ The concept of natural selection argues that organisms that have a better fit within their environmental niche will reproduce more frequently than those that fit less well. ▪ Through a gradual branching process that involves adaptation to thousands of environments, natural selection has produced the diverse plants and animals found in the world today. III. Genetics • The science of genetics aims to explain the origin of the variety upon which natural selection operates. o Biochemical changes (mutations) in DNA provide much of the variety on which natural selection operates. A. Mendel’s Experiments • The study of hereditary traits was begun in 1856 by Gregor Mendel, an Austrian monk. • By experimenting with successive generations of pea plants, Mendel came to the conclusion that heredity is determined by discrete particles or units, the effects of which may disappear in one generation and reappear in the next. • Mendel determined that the traits he observed occurred in two basic forms: dominant and recessive. o Dominant forms manifest themselves in each generation. o Recessive forms are masked whenever they are paired with a dominant form of the same trait in a hybrid individual. o It has since been demonstrated that some traits have more than these two forms— the human blood type, for example, has several forms, some of which are codominant. • The traits Mendel identified occur on chromosomes. o Humans have 23 matched pairs of chromosomes, with each parent contributing one chromosome to each pair. o Chromosomes contain several genes, which determine the nature of a particular trait. o Alleles are the biochemically different forms that may occur at any given genetic locus. o Chromosome pairs’ loci may be homozygous (identical alleles) or heterozygous (mixed). • Dominance produces a distinction between genotype, or hereditary makeup, and phenotype, or expressed physical characteristics. B. Independent Assortment and Recombination • Mendel also determined that traits are inherited independently of one another (independent assortment). • The fact that traits are transmitted independently of one another, and hence may occur in new combinations with other traits, is responsible for much of the variety upon which natural selection operates. C. The Role of DNA• Mendel demonstrated that variety is produced by genetic recombination, but mutations, or changes in the DNA molecules of which genes and chromosomes are built, are now known to be even more important as a source of new biochemical forms on which natural selection may operate. • DNA does several things basic to life. o DNA can copy itself, which forms new cells that replace old ones, and produces the gametes, or sex cells, that make new generations. o DNA’s chemical structure guides the body’s production of proteins. • Proteins are built following instructions sent by DNA, with the assistance of another molecule, RNA, which has the same paired-base structure of DNA. o In protein building, RNA carries DNA’s message from the cell’s nucleus to its cytoplasm. o A protein, or chain of amino acids, is constructed by “reading” RNA’s bases as three-letter “words” called triplets, each of which codes for a particular amino acid in order to assemble a proper sequence. o In this way DNA initiates and guides the construction of hundreds of proteins necessary for bodily growth, maintenance, and repair. D. Cell Division • An organism develops from a fertilized egg, or zygote, created by the union of two sex cells, a sperm and an egg (ovum). • A zygote grows through mitosis, or ordinary cell division, wherein one cell splits to form two identical cells. • Sex cells are produced through meiosis, a type of division wherein four cells are produced from one, each with half the genetic material of the original cell (for example, 23 chromosomes instead of 46). • Fertilization allows the products of meiosis from one parent to recombine with those from the other parent. • Chromosomes sort independently, so a human child’s genotype is a random combination of the DNA of its four grandparents. E. Crossing Over • When paired chromosomes temporarily intertwine in the course of reduplication, they often exchange lengths of their DNA. • Crossovers are the sites where homologous chromosomes have exchanged segments by breakage and recombination. • Crossing over provides an important source of variety on which natural selection operates, as each new chromosome in a crossover is partially different from eithermember of the original pair. IV. Population Genetics and Mechanisms of Genetic Evolution • Population genetics studies the genetic characteristics of populations in which most breeding normally takes place. o Gene pool refers to all the alleles, genes, chromosomes, and genotypes within a breeding population. o Genetic evolution is defined as change in gene frequencies over time, across generations. • The four principal mechanisms that produce genetic variation include natural selection, mutation, random genetic drift, and gene flow. A. Natural Selection • Essential to understanding evolution through natural selection is the distinction between genotype and phenotype. o Genotype refers to hereditary factors only—genes and chromosomes. o Phenotype is an organism’s evident biological characteristics and develops over the years as environmental forces influence the organism. • Natural selection can operate only on a phenotype, or on what is exposed, not on what is hidden. o A phenotype includes outward physical appearance as well as internal organs, tissues and cells, and physiological processes and systems. o Environmental influence in this interaction is extremely important, lending great plasticity to human biology. o The environment works on the genotype to build the phenotype, and certain phenotypes do better in some environments than others. Directional Selection • Natural selection affects gene frequencies within a population. The long-term selection of the same trait(s) is referred to as directional selection. • Directional selection occurs when specific adaptive genes are selected over a long period, causing a major shift in gene frequency. • Traits that are the most adaptive (favored by natural selection) will be selected again and again from generation to generation. • Maladaptive genes are “selected against”; that is, organisms containing them reproduce less frequently, over several generations. • Directional selection continues as long as the environmental forces stay the same;however, if the environment changes, new selective forces start working, favoring different phenotypes. • Selection operates only on traits that are present in a given population. • Some species are adapted to a narrow range of environments while others, such as Homo sapiens, tolerate more environmental variation because their genetic potential permits many adaptive possibilities. Sexual Selection • a. Sexual selection operates through competition for mates in a breeding population and through differential success in mating. Stabilizing Selection • Selective forces can maintain genetic variety through stabilizing selection—by favoring a balanced polymorphism. • This occurs when frequencies of two or more alleles of a gene remain constant from generation to generation. • One well-studied example of balanced polymorphism involves two alleles, HbA and HbS , which affect the production of the beta strain (Hb) of human hemoglobin. o Homozygous HbA produces normal hemoglobin; homozygous HbS produces lethal sickle-cell anemia; in some circumstances, heterozygosity for this gene produces the deleterious but nonlethal sickle-cell anemia. o It was discovered that in certain populations in Africa, India, and the Mediterranean, HbS existed at surprisingly high frequencies. o This is largely explained by the fact that the populations noted were in heavily malarial areas and that the heterozygous form produced a phenotype resistant to malaria, thus making it the phenotype most fit for that environment. • Traits that are maladaptive in one environment, as would be the heterozygote HbA HbS in a malaria-free zone, can be adaptive in a different environment, and the reverse is also true. B. Mutation • Mutations are the most important source of variety on which natural selection depends and operates. o The simplest mutations result from the substitution of just one base in a triplet by another. o Another form of mutation is a chromosomal rearrangement, in which pieces of a chromosome break off, turn around and reattach, or migrate somewhere else on that chromosome. ▪ A mismatch of chromosomes resulting from rearrangement can lead to speciation—the formation of a new species. • Mutation rates vary, but for base substitution mutations, the likely average is 1029 mutations per DNA base per generation—or approximately three mutations for every sex cell. • Mutations may be neutral, conferring neither advantage nor disadvantage, though they can also be harmful or acquire an adaptive advantage through changing selective forces. C. Random Genetic Drift • Random genetic drift refers to random changes in gene frequency as the result of chance (not natural selection). They are most typically seen in small populations. • Fixation—or the total replacement of genes—happens randomly, not because the genes conferred any selective advantage or disadvantage. D. Gene Flow • Gene flow, the exchange of genetic material between populations of the same species, may occur through either direct interbreeding or an indirect chain of connection. • Gene flow works in conjunction with natural selection, introducing a variety upon which selection can act. • Gene flow inhibits speciation unless subgroups of the same species are separated for a sufficient length of time. o A species is a group of related organisms whose members can interbreed to produce offspring that can survive and reproduce. o Speciation occurs when populations of the same species become isolated from each other (thus stopping gene flow), allowing natural selection and genetic drift to gradually produce gene pools that are different to the extent that successful interbreeding is no longer possible. V. Microevolution, Macroevolution, and Extinction • Microevolution and macroevolution are two ends of a continuum of evolutionary change in which gradually changing gene frequencies in a population can eventually lead to the formation of new species. o Microevolution refers to genetic changes in a population or species over a few, several, or many generations, but without speciation. o Macroevolution describes larger-scale changes in allele frequencies in a population over a long period that may culminate in the evolution of a new species. The contrast between microevolution and macroevolution should not be exaggerated. ▪ Microevolution and macroevolution happen in the same way and for the same reasons, reflecting the mechanisms of genetic evolution. A. Punctuated Equilibrium • Charles Darwin saw life forms arising through gradual, orderly microevolutionary change over time. Advocates of a theory called punctuated equilibrium believe, however, that long periods of stasis, during which species change little, are punctuated by evolutionary leaps. • Punctuated equilibrium may occur through the extinction of one species followed by the invasion of a closely related species, the replacement of one species by a more fit related group in a particular environment, and a period of sudden environmental change that permits the survival of a radically altered species with significant mutations or a combination of genetic changes. B. Extinction • Although species can survive radical environmental shifts, a more common fate is extinction. o The largest mass extinction occurred 245 million years ago and wiped out 4.5 million of the Earth’s estimated 5 million species. o The second-largest mass extinction, 65 million years ago, destroyed the dinosaurs. • The fossil record shows that there are periods of more intense evolutionary change. Speciation responds to many factors, including the rate of environmental change, changes in geographic barriers, competition, and a group’s adaptive response.

chapter 6

I. Introduction: Understanding Ourselves • Human biological diversity encompasses not just the traits visible to the naked eye like skin or eye color but also those that cannot be seen, such as disease resistance or the ability to digest certain kinds of food. o Understanding these differences, how they came to be, and what the implications are can be critical. o For instance, knowledge of a correlation between blood type and adverse reactions to the smallpox vaccine can save lives. • As a result of migration, contemporary North America is rich in biological diversity. Anthropology seeks to understand and explain it. II. Race: A Discredited Concept in Biology • Historically, the study of human biological diversity has been approached in the following two main ways: o Racial classification: the attempt to assign humans to discrete categories—races— based on common ancestry (now largely abandoned). o The explanatory approach, which focuses on understanding specific differences. • In biological terms, a race is a geographically isolated subdivision of a species that is capable of reproducing with individuals from other subspecies of the same species but does not do so because of its geographic isolation. o Humans lack such races because human populations have not been isolated enough from one another to develop into discrete groups. • Racial classification assumes that humans belong to distinct races and that each race has a biological basis. However, race is a cultural category that is perceived and perpetuated in particular societies, not a biological reality. o Discrimination against a group perceived to be biologically different is racism. o Racism has not always existed, nor is it intrinsic to humanity. • Biological differences are real, important, and apparent to all. o Gradual, rather than abrupt, shifts in gene frequencies, called clines, exist between neighboring human populations. o Race is supposed to reflect shared genetic variation, but racial categories have been based on phenotypes, which are the evident physical traits of humans. ▪ There are hundreds of detectable physical traits, ranging from skin color and hair form to blood type and enzyme production, and there is no logical hierarchy of phenotypic features. However, early European and American scientists gave priority to the readily apparent feature of skin color in determining race.o The three so-called great races—black, white, and yellow—identified in the late 19th and early 20th centuries are more a reflection of European colonial politics than an accurate representation of human biological diversity. A. Races Are Not Biologically Distinct • Another problem with classifying people by skin color is that many populations do not fit neatly into any one of the three “great races.” • Skin-color-based race models that include more than three categories still do not accurately represent the wide range of skin color diversity among human populations. • Traits such as skin color, stature, skull form, and facial features don’t go together as a unit, and the amount that heredity (versus environment) contributes to such phenotypic traits is often unclear. B. Genetic Markers Don’t Correlate with Phenotype • Humans are much more alike genetically than are other hominoids (the living apes). o This suggests that all humans share a common ancestor, perhaps as recent as 70,000 to 50,000 years ago. o The fact that African populations are the most genetically diverse points to Africa as the site of human origins. • Contemporary researchers construct haplogroups—lineages defined by specific genetic mutations—as they attempt to trace the dispersion of humans across the globe. o They sample mitochondrial DNA in women and Y chromosomes in men. o Members of the major haplogroups (M and N for mtDNA; C and F for the Y chromosome) are found throughout the globe. • Although long-term genetic markers exist, they do not correlate neatly with phenotypical similarities and differences. C. The AAA RACE Project • The American Anthropological Association (AAA) offers a RACE education program for middle-school children, with three key messages: o Race is a recent human invention. o Race is about culture, not biology. o Race and racism are embedded in institutions and everyday life. • The AAA’s statement on race stresses that inequalities among “racial” groups are not a result of biological differences but are instead products of social, economic, educational, and political circumstances. III. Human Biological Adaptation• Scientists have made considerable progress in explaining variation in human skin color, along with many other features of human biological diversity. Natural selection plays a key role. A. Explaining Skin Color • Natural selection is the process by which the forms most fit to survive and reproduce in a given environment do so. • Variation in skin color is a complex biological trait that is influenced by a number of different genes. The amount of melanin in the skin is the primary determinant of human skin color. Melanin protects against a number of maladies. • Prior to the 16th century, most of the world’s darkest-skinned populations lived closest to the tropics, and a gradient of average skin color could be observed moving north from the region of the tropics in Africa, for example. This does not hold true in the Americas, however, which were settled in the relatively recent past (no more than 20,000 years ago) by Asian ancestors of Native Americans. • Selective advantages and disadvantages (see Recap 6.1) are important factors. o Light skin in the tropics is selected against, because it burns more easily, thus subjecting light-skinned individuals to a greater likelihood of infection and disease. o Sunburn impairs the body’s ability to withstand heat by reducing the skin’s ability to sweat and regulate its own temperature in the process. o Light skin is more susceptible than dark skin to skin cancer. o The effect of sunlight on vitamin D formation indicates how dark skin might have been selected for in tropical environments, and against in lower-sunlight environments (protection against rickets); it further indicates how light skin might have been selected for in low-sunlight environments and against in the tropics. • Today, people from Pakistan and India are seen as people who have migrated to northern areas of the United Kingdom having a higher rate of rickets and osteoporosis, demonstrating that dark skin in northern areas becomes a biological disadvantage. • Eskimos (Inuit), who have darker skin, can survive in northern areas where people would expect them to have lighter skin because they have inhabited the area only recently in geological time and eat diets supplemented by high vitamin D (seafood and fish oils). When they don’t eat the traditional seafood diet, they suffer high rates of vitamin D deficiency. • Additionally, natural sunlight and UV destroy folate, a nutrient essential to preventing neural tube defects (NTDs) in humans. Higher melanin levels (leading to darker skin) conserve folate in humans. Thus, lower rates of severe folate deficiency are seen in darker-skinned people than in lighter-skinned ones. • Today, cultural alternatives to biological adaptation permit people to live all over the globe• Jablonski and Chaplin (2000) explain variation in human skin color as a balancing act between evolutionary needs to protect against all UV hazards while maintaining an adequate supply of vitamin D. B. Facial Features • Thomson’s nose rule asserts that noses tend to be longer in colder climates, an adaptive mechanism for warming air as it is breathed in. • Native Australians’ sand-permeated diet has selected over time for larger teeth than is usually seen in other human populations. C. Size and Body Build • Different climates have selected variant body types. • Bergmann’s rule states that larger bodies are found in colder areas and smaller bodies in warmer ones. o Because of the respective ratios between mass and surface area, smaller bodies dissipate heat faster and larger bodies retain heat better. D. Genes and Disease • Much of human biological diversity is the result of human genetic adaptation to environmental stresses, including diet, disease, and climate. o The high frequencies of the HbS heterozygote in malarial environments provide one example. • Infectious diseases posed an increasing threat to human mortality with the spread of food production (farming and herding) around 12,000–10,000 years ago. • Human blood types play an important role in resistance to some diseases. o There is evidence that the various alleles producing human blood types interact with infectious and noninfectious ailments. o For example, the presence of type A or AB blood cells seems to make a person more susceptible to smallpox, while the presence of O or B blood cells appears to increase resistance to smallpox. • Genetic resistance is particularly significant in the case of diseases for which there are no known cures. o People exposed to HIV vary in their risk for developing AIDS and in the rate at which the disease progresses. o Individuals who are homozygous for the allele CCR5-∆32 are resistant to invasion by the CCR5 receptor used by HIV. o This is an immunity that illustrates preadaptation or preselection. o The original selection for the allele had nothing to do with HIV, instead spreadingbecause it conferred resistance to earlier disease. E. Lactose Tolerance • The term phenotypical adaptation refers to changes that occur to an individual organism during its lifetime. Phenotypical adaptation is made possible as a result of humans’ biological plasticity, or the ability to change in response to the environments humans encounter while growing. • Individuals from herding populations in northern Europe and parts of Africa maintain their ability to digest milk (that is, they continue to produce the enzyme lactase) into adulthood, whereas people from other populations can digest milk (specifically milk sugar, called lactose) only during childhood. • A comparison of European and East African lactose tolerant groups shows that different mutations favor lactose tolerance between and within these groups, indicating that the same phenotype can be produced by different genotypes. • The fact that lactose intolerance can vary during an individual’s adult life, depending on how much milk is consumed, indicates that some phenotypic adaptation also takes place.

chapter 10