Human Biology

An Evolutionary and Biocultural Perspective

Sara Stinson, Barry Bogin, Dennis H. O'Rourke, Sara Stinson, Barry Bogin, Dennis H. O'Rourke

• Éditeur: Wiley-Blackwell
• Année: 2012
• ISBN:
  9781118108048
• Édition: 2
• Sujet: Social Sciences
• Sous-sujet: Physical Anthropology

This comprehensive introduction to the field of human biology covers all the major areas of the field: genetic variation, variation related to climate, infectious and non-infectious diseases, aging, growth, nutrition, and demography. Written by four expert authors working in close collaboration, this second edition has been thoroughly updated to provide undergraduate and graduate students with two new chapters: one on race and culture and their ties to human biology, and the other a concluding summary chapter highlighting the integration and intersection of the topics covered in the book.

PART I
INTRODUCTION

CHAPTER 1

Human Biology: An Evolutionary and Biocultural Perspective

SARA STINSON, BARRY BOGIN, DENNIS O’ROURKE, and REBECCA HUSS-ASHMORE

INTRODUCTION

What Are the Big Questions?

What is human biology and what do human biologists study? What constitutes the shared biology of people and other nonhuman species? What are the novel characteristics of the human species, and can the time of origin and the reasons for the evolution of these new and novel features be determined? What biological differences are there among and within living human populations, and how are these differences the product of both evolution over generations and plasticity during an individual’s lifetime? These are several of the “big questions” in the field of human biology. This book summarizes current research aimed at answering these questions.

The major points of this chapter are the following:

(1) Human biology is a well-defined discipline.

(2) Human biology is founded on an evolutionary perspective.

(3) The recognition of different types of biological adaptation, including processes of plasticity in development and behavior, is at the core of human biology.

(4) A biocultural and cross-cultural perspective is a unifying principle of all human biological research and thinking.

BOX 1.1 DEFINITIONS OF HUMAN BIOLOGY

There is no single, all encompassing definition of “human biology.” This is due to the fact that the biology of the human species is studied from a variety of disciplines, each with its own perspective. These disciplines vary from the practical applications of clinical medicine for the treatment of human disease to studies to better understand the basic physiological pathways and mechanisms in the human body to research aimed at understanding the adaptive/evolutionary context of human biology. Here we offer a definition and a mission statement found in university catalogs and descriptions of the topics covered in three journals with human biology in their titles to provide a taste of the diversity of thought about human biology.

1. Loughborough University Human Biology Programme definition: “Human Biology is the study of humans from the cellular and individual level to the population level. Human Biologists study human anatomical structure and function and investigate the determinants of biological and behavioural variability in people, including genetic, environmental and cultural factors. Human Biologists study how the human species evolved, how the species changes over the lifespan, how humans adapt to external stressors, and how human biology and culture influence disease risk. Graduates go on to a diverse range of careers, including research, teaching, medicine or allied professions, laboratory work or graduate training schemes. The degree is unique for its emphasis on applied, individual and population level biology and the international perspective that is generated by staff research interests.”

2. Stanford University Program in Human Biology, mission statement: “The Program in Human Biology is an interschool, interdepartmental, undergraduate major. The program’s mission is to provide an interdisciplinary approach to understanding the human being from biological, behavioral, social, and cultural perspectives. The curriculum provides a broad and rigorous introduction to the biological and behavioral sciences and their interrelationships, and explores how this knowledge, in conjunction with studies in other fields, can be applied to formulate and evaluate health, environmental, and other public policies that influence human welfare.”

3. Three journals: (1) American Journal of Human Biology: The transdisciplinary areas covered in the journal include, but are not limited to, epidemiology, genetic variation, population biology and demography, physiology, anatomy, nutrition, growth and aging, physical performance, physical activity and fitness, ecology, and evolution, along with their interactions. (2) Annals of Human Biology: A journal of human population biology, reporting investigations on the nature, development, and causes of human variation, embracing the disciplines of human genetics, auxology, environmental physiology, ecology, and epidemiology. (3) Human Biology: A worldwide forum for state-of-the-art ideas, methods, and techniques in the field, Human Biology focuses on genetics in its broadest sense. Included under this rubric are human population genetics, evolutionary and genetic demography, quantitative genetics, evolutionary biology, ancient DNA studies, biological diversity interpreted in terms of adaptation (biometry, physical anthropology), and interdisciplinary research linking biological and cultural diversity (inferred from linguistic variability, ethnological diversity, archaeological evidence, etc.).

In this chapter, we introduce the subject of this book, human biology, and the evolutionary and biocultural perspective that human biologists use in their work. While there are a number of disciplines that could (and some do) call themselves human biology because they deal with human biological characteristics, the human biology covered in this book is the discipline concerned with variation in biological traits both among and within living human populations and understanding the origin, maintenance, and implications of this variation. Human biologists investigate the genetic, environmental, and cultural determinants of biological variability in living people. They study how the human species evolved, how individual humans change over the lifespan, how humans adapt to external stressors, and how human biology and culture interact to shape disease risk.

Human biologists’ primary interest is in biological, as opposed to behavioral, characteristics. Among the main topics that human biologists study are variation in genetic traits, disease, health, nutrition, climate responses, growth, aging, and demography. One important feature of human biology is its interest in all human populations. This interest reflects the fact that most human biologists are trained as anthropologists (especially in the United States), and like anthropologists, human biologists often study remote groups whose lives are very different from those of most of the readers of this book. For example, the authors of the chapters in this book have conducted fieldwork in Alaska, Dominica, Mexico, Guatemala, Ecuador, Peru, Bolivia, Kenya, Zaire, Egypt, Tibet, Siberia, China, The Philippines, and Samoa. But human biologists also study populations in industrialized countries, and you will see many examples of this research in this book. Human biologists study populations around the world because they are interested in understanding the effects of the many different environments with which humans must cope, and are often particularly interested in responses to severe environmental stressors such as the extreme cold in Alaska and Siberia or the very high altitudes in Peru and Bolivia.

Because human biologists frequently collect data in the field, meaning outside the laboratory or hospital setting, some traits are more feasible for them to study than others. It would be very difficult (and expensive) to conduct research using CT scans on a large portion of the world’s populations. On the other hand, the instruments for measuring height and weight can be transported relatively easily to even the most remote location. As you read about human biology research, you will see the emphasis we place on developing methods that can easily be used in the field. Over the last several decades, new data collection and analysis methods have greatly increased the questions that human biologists can answer. There are now smaller instruments such as portable heart rate monitors and accelerometers to measure energy expenditure; collection methods that do not require access to electricity, such as measuring hormones from saliva rather than from whole blood; and techniques that reduce the burden on the research participants, such as analysis of blood proteins from spots of blood, from a finger prick, dried on filter paper, rather than from blood drawn from a vein.

Human biologists study individuals, but their primary interest is in the characteristics of groups of individuals, called populations; in fact, the discipline is sometimes called human population biology (Baker 1982; Little and Haas 1989). The importance of populations to the human biologist is illustrated by comparing human biology with Western medicine (frequently called biomedicine), another discipline that is concerned with human biological traits. Both biomedical doctors and human biologists are interested in the biological characteristics of groups, but the main reason for this interest is different. In biomedicine, knowing the blood pressure of an individual is important mainly because it can be used to determine if the value is outside the normal clinical range, and thus if the patient is ill and in need of medical treatment. The “normal clinical range” is that found for people within the clinical population. In the industrialized Western nations of the United States, Canada, the European Union, Australia, and Japan, the clinical population is usually comprised of men of middle and upper socioeconomic status. Women, children, and ethnic minority groups are often not well represented in clinical reference values, even though there has been an effort to increase the participation of women and minorities in recent years (Department of Health and Human Services 1994; http://grants.nih.gov/grants/funding/women_min/guidelines_amended_10_2001.htm; Murthy et al. 2004). In the United States, the National Institutes of Health has explicit guidelines about including women and minorities in studies. Despite these efforts, there has been only limited improvement in the representativeness of biomedical research. Human biologists, on the other hand, are interested in knowing the average blood pressure and range of variation of populations to be able to compare values among and within groups, and to use these comparisons to make statements about population variation. Groups of nonindustrialized people, the hunter–gatherers, horticulturalists, pastoralists, and traditional agriculturalists studied by anthropologists/human biologists often have lower blood pressure than people in Western, industrialized nations (see Chapter 13).

Human biologists’ interest in comparison leads naturally to the questions of how variation arises, why characteristics do or do not persist in given situations, and what are the larger implications of human biological diversity. To understand how human biologists go about answering these questions, we need to look at the explanatory framework that human biologists use: an evolutionary and biocultural perspective. As Peter B. Medawar (1964), who was awarded the Nobel Prize for his work on tissue grafting and was an important theorist of aging, wrote, “Human Biology is not so much a discipline as a certain attitude of mind… .”

EVOLUTIONARY PERSPECTIVE

Human biologists need to account for biological change over time as well as the distribution of traits in space. As a result, human biologists—like most other biological scientists—use the synthetic theory of evolution as their primary explanatory framework.

What do we mean by the “synthetic” theory of evolution? This term refers simply to the fact that the modern theory of evolution is a synthesis of Darwinian theory (Charles Darwin, 1809–1882, published Origin of Species in 1859) and the science of genetics. Darwinian theory revolves around the principles of natural selection. At its simplest, Darwin’s theory has four basic tenets: (1) More organisms are produced than can survive; (2) organisms within a species vary in their traits; (3) some of this variation is heritable; and (4) variants best suited to the environment survive to be represented in the next generation. Mendelian genetics (Gregor Mendel, 1822–1884, proposed that inherited traits are discrete particles) provided a plausible explanation of how variation is inherited. Molecular biology and cytogenetics of the 20th century clarified how variation arises at the level of the deoxyribonucleic acid (DNA) molecule (genetics is explained in more detail in Chapter 3). Another way to explain natural se...