Summaries of chapters Flashcards
1
Q
Chapter 1
A
▶ The chapter objective was to introduce the fields of physical anthropology and archaeology and place
them within the overall context of
anthropology, a social science that
also includes cultural anthropology
and linguistics as major subfields.
▶ Physical anthropology studies
aspects of human biology (emphasizing evolutionary perspectives),
nonhuman primates, and the hominin fossil record. Physical anthropologists are interested in how
hominins came to possess culture
and how this process influenced
the direction of human evolution.
Especially regarding the study of
early hominins, physical anthropologists work in close collaboration
with many specialists from archaeology, geology, chemistry, and other
disciplines that form the interdisciplinary field of paleoanthropology.
▶ Archaeology provides time depth
for our understanding of humans as
biocultural organisms. Systematic
examination of the archaeological
record provides the basis for archaeologists’ interpretations of extinct
lifeways as well as the construction
of cultural chronologies, explanations for observable cultural changes, and interpretations of the cognitive and symbolic patterns that
mark our past. Like the larger field
of paleoanthropology (which also
draws heavily on archaeological
methods), archaeological research
involves input from many related
disciplines. This collaborative examination of the archaeological record
yields nearly all we know, if not all
we are likely to ever know, about
prehistoric human behavior and
activities.
2
Q
Chapter 2
A
▶ Our current understanding of evolutionary processes is directly traceable to developments in intellectual thought in western Europe and the East over the past 400 years. Darwin and Wallace were able to discover the process of natural selection and evolution because of the discoveries of numerous scientists who had laid the groundwork for them. Among others, Galileo, Lyell, Lamarck, Linnaeus, and Malthus all contributed to a dramatic shift in how people viewed the planet and themselves as part of a system governed by natural processes. ▶ Charles Darwin and Alfred Russel Wallace recognized that there was variation among individuals in any population (human or nonhuman). By understanding how animal breeders selected for certain traits in cattle, pigeons, and other species, Darwin formulated the theory of natural selection. Stated in the simplest terms, natural selection is a process whereby individuals who possess favorable traits (characteristics that permit them to survive and reproduce in a specific environment) will produce more offspring than individuals who have less favorable traits. Over time, the beneficial characteristics will become more frequent in the population, and the makeup of the population (or even a species) will have changed. ▶ As populations of a species become reproductively isolated from one another (perhaps due to distance or geographical barriers), they become increasingly different as each population adapts, by means of natural selection, to its own environment. Eventually, the populations may become distinct enough that they can no longer interbreed; at this point, they are considered separate species. ▶ In the United States, and increasingly in some Muslim countries, evolutionary processes are denounced because they are seen as contradictory to religious teaching. In recent years, Christian fundamentalists in the United States have argued in favor of teaching “creation science” or “intelligent design” in public schools. So far, courts have ruled against various attempts to promote “creation science” because of separation of church and state as provided for in the U.S. Constitution
3
Q
Chapter 3
A
▶ Cells are the fundamental units
of life. They can be either somatic
cells, which make up body tissues,
or gametes (eggs and sperm), which
are reproductive cells that transmit
genetic information from parent to
offspring.
▶ Genetic information is contained in
the DNA molecule, found in a cell’s
nucleus. The DNA molecule is capable of replication (making copies of
itself) during mitosis and meiosis.
DNA also controls protein synthesis
by directing cells to arrange amino
acids in the proper sequence for
each particular type of protein.
▶ Gregor Mendel discovered the principles of segregation, independent
assortment, and dominance and
recessiveness by doing experiments
with pea plants. Characteristics
influenced by only one genetic locus
are called Mendelian traits. In contrast, many characteristics, such as
stature and skin color, are polygenic, meaning that they’re influenced
by more than one genetic locus
and show a continuous range of
expression.
▶ Building on fundamental
nineteenth-century contributions
by Charles Darwin and the rediscovery of Mendel’s work in 1900,
advances in genetics throughout
the twentieth century contributed to contemporary evolutionary
thought. In particular, the combination of natural selection with
Mendel’s principles of inheritance
and experimental evidence concerning the nature of mutation have
all been synthesized into a modern understanding of evolutionary
change, appropriately termed the
Modern Synthesis.
▶ In this contemporary theory of evolution, evolutionary change is seen
as a two-stage process. The first
stage is the production and redistribution of genetic variation. The
second stage is the process whereby natural selection acts on that
variation.
▶ Mutation is crucial to all evolutionary change because it’s the only
source of completely new genetic
material (which increases variation).
▶ Natural selection is the crucial factor
that influences the long-term direction of evolutionary change. How
natural selection works can best be
explained as differential net reproductive success—that is, how successful individuals are in producing
offspring for succeeding generations. Genetic drift (the random loss
of alleles due to small population
size) and gene flow (the exchange
of genes between populations) are
also very important to evolutionary
change.
4
Q
Chapter 4
A
▶ Physically visible traits, traditionally used in attempts to classify humans into clearly defined groups (“races”), have emphasized such features as skin color, hair color, hair form, head shape, and nose shape. ▶ However, all of these physical characteristics are not only influenced by several genetic loci but are also modified by the environment. As a result, these traditional markers of race aren’t reliable indicators of genetic relationships, and they’re not biologically useful in depicting patterns of human diversity. ▶ Since the 1990s, the development and rapid application of comparative genomics have drastically expanded genetic data. Current population studies are aimed at reconstructing the microevolutionary population history of our species and understanding the varied roles of natural selection, genetic drift, gene flow, and mutation. ▶ For humans, culture also plays a crucial evolutionary role. Interacting with biological influences, these factors define the distinctive biocultural nature of human evolution. Two excellent examples of recent human biocultural evolution relate to resistance to malaria (involving the sickle-cell allele) and lactase persistence. ▶ Another major focus of modern human biological studies concerns adaptation. Skin color variation is one characteristic that is investigated to understand how it has evolved in different populations and the role of natural selection balancing the effects of UV radiation and the requirements for adequate production of vitamin D. ▶ Other well-documented examples of modern human adaptation include adaptations to heat, cold, and high altitude. ▶ Cultural innovations and contact with nonhuman animals have increased the spread of many infectious diseases, including HIV/AIDS, influenza, and malaria.
5
Q
Chapter 5
A
▶ To understand the large-scale evolutionary history of life on earth, two major organizing perspectives prove indispensable: (1) schemes of formal classification to organize organic diversity and (2) the geological time scale to organize geological time. ▶ There are two differing approaches to classifying and interpreting lifeforms: evolutionary systematics and cladistics. ▶ Because primates are vertebrates and, more specifically, mammals, it’s important to understand how these major groups are connected to our own origins. ▶ Theoretical perspectives relating to contemporary understanding of macroevolutionary processes (especially the concepts of species and speciation) are crucial to any interpretation of long-term aspects of evolutionary history, be it vertebrate, mammalian, or primate. ▶ Because genus and species designation is the common form of reference for both living and extinct organisms (and we use it frequently throughout the text), it’s important to understand how these terms are used and their underlying biological significance.
6
Q
Chapter 6
A
▶ The mammalian order Primates includes humans and approximately 230 nonhuman species: apes, monkeys, tarsiers, and lemurs. Most nonhuman primates live in tropical and subtropical regions of Africa, India, Asia, Mexico, and South America. ▶ The order Primates is divided into two suborders: Strepsirhini (lemurs and lorises) and Haplorhini (tarsiers, monkeys, apes, and humans). ▶ As a group, the primates are very generalized, meaning they’ve retained many anatomical characteristics that were present in early ancestral mammalian species. These traits include five digits on the hands and feet, different kinds of teeth, and a skeletal anatomy and limb structure that allow for different forms of locomotion (climbing, brachiation, quadrupedalism, and bipedalism). ▶ In general, primates have relatively larger, more complex brains than other mammals. ▶ Most primates are diurnal and live in social groups. ▶ Because of habitat loss and human hunting, the majority of nonhuman primates are endangered today, and some are on the verge of extinction. Without concerted efforts to preserve primate habitat and control hunting, many species, including mountain gorillas, bonobos, chimpanzees, and many monkeys, could well become extinct by 2050.
7
Q
Chapter 7
A
▶ One of the major goals of primatology is to discover how certain behaviors influence reproductive fitness and how ecological factors have shaped the evolution of those behaviors. ▶ Behavioral ecology is the discipline that examines behavior from the perspective of complex ecological relationships and how they influence natural selection as it favors behaviors that increase reproductive fitness. ▶ Primates are among the most social of animals, but within social groups there is competition for resources and conflict. Dominance hierarchies help reduce the amount of physical aggression. Also, there are numerous amicable behaviors, such as grooming, that maintain peaceful relationships between individuals. ▶ Communication makes it possible to live in social groups. It occurs in many forms, including vocalizations and gestures. Some primate species are able to communicate about certain aspects of the external environment, indicating some ability to think symbolically. ▶ Several nonhuman primates exhibit aspects of culture, including tool use and regional variation in dietary preferences. Chimpanzees use stones to crack palm nuts in some populations but not in others; some savanna chimpanzees use sharpened sticks to hunt for galagos; and capuchins that live in savannalike habitats use stones to crack nuts and dig for roots. ▶ Long-term language studies with the great apes have shown that these species have the ability to communicate using different kinds of symbols, including sign language. ▶ Biological and behavioral continuity within the primate order reveals how humans are connected to our closest relatives and allows us to explain some aspects of human behavior.
8
Q
Chapter 8
A
▶ To achieve any meaningful understanding of human origins, we must examine both biological and cultural information about the past. ▶ The multidisciplinary approach of paleoanthropology brings together varied scientific specializations to reconstruct the anatomy, behavior, and environments of early hominins. ▶ Archaeology studies the human past primarily through its material remains. Its scope extends roughly from 2.6 mya, with the earliest identified early hominin tools and toolmaking debris, up to the twenty-first century. Archaeologists make the key assumption that the organization and structure of the archaeological record reflects the behavior of humans in the past. ▶ One of the main tasks of this chapter has been to describe the varied ways in which researchers estimate past time. For paleoanthropologists and archaeologists alike, time rather than space is the important dimension that separates us from those we study. ▶ The Olduvai Gorge example illustrates the application of many of the research and dating methods described in this chapter. It also motivates our examination of early hominin paleoanthropological research, which we take up in the next chapter.
9
Q
Chapter 9
A
▶ The earliest very primitive primates evolved in the Paleocene around 65 mya. ▶ Many primate fossil forms more similar to living primates evolved in the Eocene (56–33 mya). Most of these species went extinct, although some show connections to modern lemurs/lorises or to tarsiers. ▶ The first anthropoids probably date to the late Eocene, but are much better documented from the Fayum Oligocene site (about 33 mya). ▶ Large-bodied hominoids are widespread and diverse in the Old World throughout the entire Miocene (23–5 mya). ▶ The first hominins appear 7–6 mya, and for the next 5 million years are all restricted to Africa. ▶ Many species of these early African hominins have been identified and can be summarized within three major subgroups: • Pre-australopiths (6.0+–4.4 mya) – Including three genera of very early, and still primitive (possible) hominins: Sahelanthropus, Orrorin, and Ardipithecus • Australopiths (4.2–1.2 mya). – Early, more primitive australopith species (4.2–3.0 mya), including Australopithecus anamensis and Australopithecus afarensis – Later, more derived australopith species (2.5–1.2 mya), including two genera: Paranthropus and a later species of Australopithecus • Early Homo (2.4–1.4 mya) – The first members of our genus, who around 2 mya likely diverged into more than one species ▶ The earliest known stone tools date to about 2.6 mya, but cut marks on bones and other evidence suggest that hominins were perhaps tool users more than 3.3 mya. ▶ Hominin tool use was such a fundamental change that our subsequent evolution turned in a completely new direction to one that is both biological and cultural. It also marked the beginning of the archaeological record.
10
Q
Chapter 10
A
▶ Homo erectus remains have been found in Africa, Europe, and Asia dating from about 1.8 mya to at least 100,000 ya—and probably even later—and thus this species spanned a period of more than 1.5 million years. ▶ H. erectus likely first appeared in East Africa and later migrated to other areas. This widespread and highly successful hominin displays a new and more modern pattern of human evolution. ▶ H. erectus differs from early Homo, with a larger brain, taller stature, robust build, and changes in facial structure and cranial buttressing. ▶ The long period of H. erectus existence was marked by a remarkably slow rate of technological change compared to modern human culture. Even so, equipped with more sophisticated tools (as part of the Acheulian industry) and a growing cultural capacity to adapt to new habitats and environments, H. erectus populations spread quickly across much of the Old World. The most important fossil discoveries discussed in this chapter are summarized in “What’s Important.”
11
Q
Chapter 11
A
▶ Premodern humans from the Middle Pleistocene show similarities both with their predecessors (H. erectus) and with their successors (H. sapiens). They’ve also been found in many areas of the Old World—in Africa, Asia, and Europe. ▶ Most paleoanthropologists call the majority of Middle Pleistocene fossils H. heidelbergensis. Similarities between the African and European Middle Pleistocene hominin samples suggest that they all can be reasonably seen as part of this same species, although contemporaneous Asian fossils don’t fit as neatly into this model. Further support for this view comes from the Middle Paleolithic archaeological record, which doesn’t vary consistently across premodern human species. ▶ Neandertals have been considered quite distinct from modern H. sapiens, but recent genetic evidence confirms that some interbreeding took place between these hominins (likely 80,000–50,000 ya). ▶ The composite tool was one of the most significant Middle Paleolithic technological innovations. It enabled the creation of new kinds of tools, made many existing tools more effective, and may have coevolved with grammatical language. The pace of cultural change began to accelerate as the use of composite tools became widespread. In “What’s Important,” you’ll find a useful summary of the most significant premodern human fossils discussed in this chapter.
12
Q
Chapter 12
A
▶ Two main hypotheses have been used to explain the origin and dispersal of modern humans: – The regional continuity model suggests that different groups of modern people evolved from local populations of premodern humans. – Various replacement models, especially those emphasizing partial replacement, suggest that modern humans originated in Africa and migrated to other parts of the world. However, when they came into contact with premodern human groups, they did not completely replace them, but interbred with them to some extent. ▶ New DNA evidence from ancient Neandertals as well as from modern people demonstrate that some modest interbreeding did take place, probably between 80,000 and 50,000 ya. These findings clearly support a partial replacement model. ▶ Archaeological finds and some fossil evidence (although the latter is not as well established) also support the view that intermixing occurred between modern H. sapiens and Neandertals. ▶ The earliest fossil finds of modern H. sapiens come from East Africa (Ethiopia), with the oldest dating to about 200,000 ya. The second find from Herto is very well dated (160,000 ya) and is the best evidence of an early modern human from anywhere at this time. ▶ Modern humans are found in South Africa beginning around 100,000 ya, and the first anatomical modern H. sapiens individuals are found in the Middle East dating to perhaps more than 100,000 ya. ▶ The Upper Paleolithic is a cultural period traditionally viewed as showing many innovations in technology, development of more sophisticated (cave) art, and, in many cases, elaborate burials rich in grave goods. Similar cultural developments occurred in Eurasia and Africa. ▶ Many of the cultural innovations that have been long attributed to the Upper Paleolithic appear to have originated tens of thousands of years earlier during the Middle Stone Age of Africa. Recent archaeological research in Africa is rapidly revising our understanding of the beginnings of modern human behavior. In “What’s Important,” you’ll find a useful summary of the most significant fossil discoveries discussed in this chapter.
13
Q
Chapter 13
A
▶ By the early to middle Holocene, modern humans had expanded into all the inhabitable regions of the globe. ▶ The first humans arrived in the New World from northeastern Asia between 30,000 and 13,500 ya, most likely after 16,500 ya. They entered the New World on foot by way of the Bering land bridge, on foot or by boat along the Pacific coastal route, or by some combination of the two routes. ▶ The earliest New World skeletal evidence shows considerable morphological diversity, but cultural and biological traces clearly link the first Americans with their northeast Asian roots. ▶ There are general similarities of material culture between the earliest sites in the Americas and northeastern Asia. ▶ By about 12,000 ya, after the end of the last Ice Age, significant climatic changes altered the weather, seasonal variations, average temperatures, topography, sea levels, and animal and plant communities across much of the Northern Hemisphere, including North America and Eurasia. ▶ Many species of megafauna became extinct during the Late Pleistocene, particularly in North America; Paleo-Indian hunters may have contributed to the demise of mammoths and a few other species. ▶ Early Holocene foragers in Europe, the Near East, and North America adapted readily to the ongoing environmental changes. Generalized food-getting economies promoted long-term cultural stability for many hunter-gatherers ▶ Long-term, and in some cases permanent, settlements became part of Holocene hunter-gatherer lifeways in many regions. ▶ Sites like Ohalo II demonstrate that some food-collecting communities experienced economic changes as long ago as the Last Glacial Maximum, which led to the use of a wide range of wild plants and animals as food. The next two chapters of this text are organized around two primary cultural developments associated with humans in the later Holocene epoch: first, the process of food production, and second, the rise of civilizations. Much of what we associate with modern humanity is linked to these central driving forces. In “What’s Important,” you’ll find a useful summary of the most important archaeological sites discussed in this chapter.
14
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Chapter 14
A
▶ The early Holocene rise of plant and animal domestication and the invention of agriculture is called the “Neolithic revolution.” Agriculture soon became a major force in human biocultural evolution. ▶ Major theories to explain the development of agriculture fall into two broad groups: ● Environmental approaches: External or natural forces were the active ingredients in the development of agriculture. Human agency played little role. ● Cultural approaches: Human agency and culture was sufficient to push some societies to seek ways to increase locally available food resources. Environmental factors played little role. ▶ The origins of domestication and agriculture are complex problems for which there may be multiple valid explanations. ▶ Plant microfossils (phytoliths, starch grains, pollen) are important new data sources for the reconstruction of the development of plant domestication. ▶ The Old and New World examples show that in those areas where food production was adopted, farming transformed human subsistence, technology, society, habitation patterns, relationships with other species, and much more. In a few areas of the world, the emergence of large-scale, complex societies followed quickly on the heels of the Neolithic revolution. In Chapter 15, we’ll consider the development and course of early civilizations founded on Neolithic food-producing economies in the Old World and in the Americas. In “What’s Important,” you’ll find a useful summary of the most important archaeological sites discussed in this chapter.
15
Q
Chapter 15
A
▶ The earliest civilizations developed independently in several world regions directly after people achieved sustainable food production. ▶ Environmental and cultural factors are insufficient by themselves to explain the rise of the earliest civilizations. ▶ The earliest civilizations found only a limited number of ways to create new decision-making institutions and the distribution of power and authority. ▶ Broad similarities exist between the earliest Old and New World civilizations, but there are also important differences. ▶ New World civilizations emerged in more ecologically diverse locations than those of the Old World. ▶ New World civilizations also relied less than their Old World counterparts on domesticated animals, wheels, or metal for technological purposes. In “What’s Important,” you’ll find a useful summary of the most important archaeological sites discussed in this chapter. And in the final chapter of the book, we’ll consider some of the important points to be derived from the story of human biocultural evolution.
