Determination of the relative or absolute age of materials or objects by measurement of the degree of racemization of the amino acids present. With the exception of glycine, the amino acids found in proteins can exist in two isomeric forms called d- and l-enantiomers. Although the enantiomers of an amino acid rotate plane-polarized light in equal but opposite directions, their other chemical and physical properties are identical. Amino acid handedness or homochirality is one of the most distinctive features of terrestrial life. It was discovered by L. Pasteur around 1850 that only l-amino acids are generally found in living organisms, but scientists still have not formulated a convincing reason to explain why life on Earth is based on only l-amino acids. See also: Amino acids

The observation, measurement, and explanation of human variability in time and space. Anthropology is a science concerned with the interrelations of the biological, cultural, geographical, and historical aspects of humankind, including modern human beings and their ancestors (Fig. 1). It also includes the study of biological variability and the study of cultural, or learned, behavior among contemporary human societies. In general, anthropological studies are closely allied with the fields of archeology and linguistics. Studies range from rigorously scientific approaches, including investigations into the physiology, demography, and ecology of hunter-gatherers, to more humanistic research on symbolism and ritual behavior. See also: Archeology; Bioarcheology; Dental anthropology; Forensic anthropology; Human biological variation; Human ecology; Molecular anthropology; Origins of symbolic behavior; Physical anthropology; Sociobiology

The systematic quantitative representation of the human body. Anthropometric techniques are used to measure the absolute and relative variability in size and shape of the human body.

The interdisciplinary study that attempts to determine how much astronomy prehistoric people knew and how it influenced their lives. Archeoastronomy (Fig. 1) involves multiple disciplines: astronomy to chart the heavens, archeology to probe the cultural context, engineering to survey sites, and anthropology and ethnology to provide clues to the cultural past. Archeoastronomy has prompted valuable insights into the astronomy of the past and has even revolutionized some models of prehistoric cultures, given that the sky can perform a special role in the scheme of cultural systems. Archeoastronomy and its loose family of disciplines are sometimes subsumed under a broader field of study called cultural astronomy. See also: Anthropology; Archeology; Astronomy; Engineering

The application of chemical techniques to the study of archeological materials in order to elucidate aspects of the human past. The materials used in archeological chemistry might be anthropogenic (for example, pottery or metal) or natural (from worked stone tools to animal or plant remains that were accidentally included in the archeological deposit), and they range in scale from the microscopic to an entire landscape. See also: Anthropology; Archeology; Chemistry; Dating methods

The establishment of the temporal sequence of prehistoric events. An event can be defined as a duration of time during which certain features came together to form a set, for example, when certain materials were formed into an object (manufacturing event) or when a set of objects were deposited at a single location (occupation event). An event can be dated only if the relevant features have properties that are dependent on time. A distinction is drawn often between dating events, which are those events that can be dated, and target events, which are the events of interest. Where these do not coincide, “bridging arguments” are required to link them.

The scientific study of past material culture. The initial objective of archeology (often spelled archaeology) is to construct cultural chronologies that order past material culture into meaningful temporal segments. The intermediate objective is to breathe life into these chronologies by reconstructing past ways of life (Fig. 1). The ultimate objective of contemporary archeology is to determine the cultural processes that underlie human behavior, both past and present. Thus, archeology is both scientific and humanistic. Throughout many parts of the world, archeology is considered a subdiscipline of anthropology, focusing on the anthropology of past cultures. In other parts of the world, archeology is regarded as an extension of history, attempting to write a prehistory of people who may lack a written history of their own. See also: Anthropology; Archeological chronology; Bioarcheology; Physical anthropology; Prehistoric technology

The application of chemistry to the technical examination, authentication, and preservation of cultural property. Chemists working in museums engage in a broad range of investigations, most frequently studying the chemical composition and structure of artifacts, their corrosion products, and the materials used in their repair, restoration (see illustration), and conservation. The effects of the museum environment, including air pollutants, fluctuations in temperature and relative humidity, biological activity, and ultraviolet and visible illumination, represent a second major area of research. A third area of interest is the evaluation of the effectiveness, safety, and long-term stability of materials and techniques for the conservation of works of art. Though analytical techniques appear to dominate, many other areas of chemistry, biology, physics, and engineering, including polymer chemistry, kinetic studies, imaging methodologies, biodegradation studies, dating methods, computer modeling, metallography, and corrosion engineering, play active roles in conservation science.

Any member of an adaptively diverse group of extinct hominin species that inhabited Africa between approximately 4.2 million years ago (MYA) and 1.2 MYA. The term australopith is used in preference to the term australopithecine, which is sometimes still erroneously employed in the paleoanthropological literature, because australopithecine implies that its members form a meaningful taxonomic group (that is, the Australopithecinae) and it is clear that they do not. Rather, the australopiths are a paraphyletic group of species that are linked by relatively few morphological features, but which are believed to share a general “adaptive grade.” In addition to being bipedal (a characteristic shared by all hominins), they possess an ape-sized brain (approximately 350–550 cm³; 21–34 in.³); small, nonhoning canines, relatively large premolars and molars with thick enamel; and thickly buttressed mandibles. There are nine species considered as australopiths and although some workers regard them all as belonging to a single genus, Australopithecus, it is evident from numerous studies that at least two and possibly three genera are represented. All nine australopith species are known only from Africa; the fossils come from a wide geographical area, encompassing parts of South Africa, Malawi, Tanzania, Kenya, and Ethiopia. The species are listed in the table, together with their currently known geographical and geochronological distributions. Their geochronological distribution is compared with other hominin species in Fig. 1. See also: Anthropology; Apes; Fossil apes; Fossil humans; Fossil primates; Molecular anthropology; Physical anthropology

The study of skeletal remains from archeological sites by biological (or physical) anthropologists. Bioarcheology differs in several ways from traditional skeletal research (see illustration). Previous work focused on individual case studies (for example, individuals with identifiable diseases) or on typological analyses of cranial form. Bioarcheology looks at populations rather than individuals, often highlighting variation within groups as much as differences between them. In addition, it considers the interaction of biology with human culture and behavior, and the effects of the latter upon skeletal morphology or form. Technological advances in computers and methodology have opened up new fields of study, such as biomechanics and paleonutrition, while revolutionizing older interests, such as biological distance studies (a measure of genetic relatedness). Finally, bioarcheology, in part because of the specialized nature of some subfields and in part because of its biocultural approach, emphasizes collaboration with other anthropologists as well as researchers in other disciplines. See also: Anthropology; Archeology; Physical anthropology