INTRODUCTION

BONES HAVE BEEN ENTOMBED for millions of years in sediments left by ancient lakes, swamps, and rivers that once dotted Ethiopia’s Afar Depression. Today, as erosion cuts into these ancient layers, the fossils reach the barren Afar surface, often shattering into small, glistening, multicolored fragments of bone and teeth. Thinly scattered among the osseous and dental remains of thousands of crocodile, turtle, hippopotamus, giraffe, carnivore, baboon, pig, horse, antelope, and other animals found in the surface fossil assemblages are the remains of primitive human ancestors. While paleontologists search Afar outcrops for osteological clues about prehistoric human form, archeologists uncover the osteological remains of the inhabitants of Herculaneum who perished as Mount Vesuvius erupted, burying them with their possessions. On the other side of the globe, anthropologists probe into a recent grave containing skeletal parts that may be those of a Nazi war criminal.

1.1 Human Osteology

A thread that binds these and thousands of other investigations is human osteology, the study of human bones. The scientists performing the investigations employ their knowledge of the human skeleton in recovering and interpreting the bones. Outside of anatomical and medical science, there are three main areas in which knowledge of human osteology is often applied. First, osteological work is often aimed at identification of the relatively recently deceased and is usually done in a legal context. This work, which pertains to the public forum, most often a court of law, is called forensic osteology, a division of forensic anthropology. The other two contexts in which human osteological knowledge is commonly applied are historical. The context can be ancient and purely paleontological, as for the Pliocene pre-cultural hominids of Africa. Alternatively, the context can be relatively recent, part of an archeological record. For example, human bones recovered from the Aztec centers in Mexico were chronicled just a few hundred years ago by the Spanish during the “conquest” of Mexico. Osteological analysis of materials from such cultural contexts is routinely undertaken as part of archeological research. Archeologists concentrate on cultural residues of former human occupations, but they stand to gain a great deal of valuable information from the skeletal remains of the ancient inhabitants. It has recently become fashionable to refer to the study of human remains from archeological contexts as bioarcheology. However, human skeletal parts are only a small part of the biological remains characterizing most archeological sites — indeed, most archeological sites lack human remains altogether!

The information that human or protohuman bones can provide makes the recovery of bones a critically important activity. Skeletal anatomy (including teeth) reflects the combined action of genes and environment. The skeleton forms the framework for the body, whereas the teeth form a direct interface between the organism and its environment. Bones carry in their shape, or morphology, the signature of soft tissues with which they were embedded during life — tissues including muscles, ligaments, tendons, arteries, nerves, veins, and organs. These soft tissues usually disappear soon after death. The skeleton, however, often preserves evidence of the former existence and nature of many of these other body parts.

Because the bones and teeth of the skeleton are resistant to many kinds of decay, they often form the most lasting record of an individual’s existence. It is possible to estimate an individual’s age, sex, and stature from the bones and teeth. Study of the skeleton often makes it possible to discern a variety of pathologies from which the individual may have suffered. Analysis of groups of individuals may offer insights into prehistoric population structure, biological affinities, cultural behaviors, and patterns of disease. The evolutionary history of humanity itself may be read from the fossil record — a record comprising mostly teeth and bones. Figure 1.1 illustrates the place of osteology in relation to other scientific disciplines.

1.2 A Guide to the Manual

The goal of forensic osteology often involves identification of an unknown individual. The process of personally identifying the remains of the recently dead individual is called individuation. To narrow the possibilities, the forensic osteologist first ascertains whether the remains are human and then begins to explore the individual characteristics, such as age, sex, and stature, comparing these variables in the hopes of obtaining an exclusive match with what is known about the missing individual. The human osteologist working in an archeological context usually cannot perform such personal identification. Rather, concerns are with characteristics of the individual and with the insights that skeletal remains of many individuals, representing biological populations, might provide on diet, health, biological affinity, and population history. The osteologist working in a paleontological context (and note that many fossils of Pliocene and Pleistocene age are found in archeological contexts) is also interested in using the normally rare fossil remains of human ancestors and other relatives to learn all these things and also to discern evolutionary relationships.

Skeletal remains can provide meaningful clues about the recent and the ancient past to all these investigators. To use these clues, one must master some fundamentals. The first two basic questions that any human osteologist must answer about a bone or collection of bones whether in a forensic, archeological, or paleontological context are:

Whether the context is forensic, archeological, or paleontological, these questions usually must be answered before further analysis is possible. This manual, a guide to human osteology, emphasizes the anatomy of the human skeleton. The skeletal remains of some other animals, particularly when fragmentary, are often difficult to distinguish from human bones and teeth. Although there are no general differences that ensure effective sorting between human and nonhuman bones, the first step in answering the question of whether the bones are human is to become familiar with the human skeleton in all of its many variations in shape and size. Ubelaker (1989, Fig. 63) illustrates whole bones of mammals most often confused with humans, but this confusion rarely involves whole bones. Fragmentary nonhuman remains are more problematic and are encountered more frequently. Once a familiarity with the range, or envelope, of variation characterizing the modern human species is achieved, further work in comparative osteology of both extinct and extant mammals becomes a much easier task. With further comparative work comes more experience, and with that experience the osteologist is better able to make the basic identifications required.

Information on determining the age, sex, stature, and identity of skeletonized individuals is provided in later chapters of the manual. These second-level questions and many others, including those about biomechanical capability, phylogenetic relationships, and geographic affinities, however, can be answered accurately only after the elements and individuals have been identified correctly. Too often the first, basic identifications are overlooked or hastily performed, and thus any succeeding analyses are built on weak foundations.

Chapters 7–16 form the core of the book. In these chapters we consider one anatomical region at a time, beginning with the bones of the skull. A separate chapter and format are employed for the dentition. We introduce Chapters 7–16 with brief accounts of the phylogenetic history of the body segment(s) and osteological elements described in the chapter. This approach sets the osteological elements in a broad evolutionary framework. These introductory statements are mostly drawn from the excellent functional human anatomy text by Cartmill, Hylander, and Shafland (1987), and the interested reader may pursue further details there and in other comparative texts...