Supplements The following students supplements are available with the textbook: • The Kottak Anthropology Atlas, available shrink-wrapped with the text, offers 26 anthropology related reference maps. • The Student's Online Learning Center features a large number of helpful study tools and self quizzes, interactive exercises and activities, links, readings and useful information at www.mhhe.com/kottak. • PowerWeb, available via a link on the Student's Online Learning Center, offers help with online research by providing access to high quality academic sources."
This chapter discusses the emergence of the genus Homo. It discusses the dispersal of Homo erectus beyond Africa and the emergence of Anatomically Modern Humans. Modern Humans
Early Homo • Finds in East Africa indicate the Homo habilis was not very different from the australopithecines in terms of body size and shape. • The earliest Homo erectus remains indicate rapid biological change. • The fossil record for the transition from H. habilis to H. erectus supports the punctuated equilibrium model of evolution.
Gradual and Rapid Change • Gradualism is a model of evolution proposing that most species were produced by the gradual, steady effects of natural selection operating on whole populations. • Punctuated equilibrium is a model proposing that most species were produced by genetic drift, occurring in relatively quick leaps (of 50,000 years, or so) interspersing long periods of relative stasis (of several million years). • Transitional fossils, such as those documenting the development of heavy grinding structures among the australopithecines, are thought to support gradualism. • An absence of transitional fossils, despite the presence of sequentially related species, is used as evidence supporting punctuated equilibrium.
Gradual and Rapid Change: Early Homo • The early Homo fossil sequence displays rapid change and therefore supports punctuated equilibrium. • One possible key to explaining such rapid change may lie in H. erectus’ greater reliance on cultural means of adaptation. • With the emergence of H. erectus there is a rapid proliferation in the number and diversity of tools being made. • Cultural treatment of food began to select for smaller dentition. • Cultural manipulation of the environment allowed erectus to exploit a wider array of environments.
Paleolithic Tools • Three Paleolithic Divisions • Lower Paleolithic (Homo erectus). • Middle Paleolithic (archaic Homo sapiens, including Neandertals). • Upper Paleolithic (Homo sapiens sapiens, up to 15,000 years ago). • Technique Differentiation • Paleolithic stone toolmaking was marked by advancing refinement of technique, recognizable groupings of which are called toolmaking traditions. • A basic distinction is between core and flake tools. • The primary tradition of the Lower Paleolithic is the Acheulian.
Adaptive Strategies of Homo erectus • Culture/Biology Synergy • Acheulian tools and essentially modern bipedalism aided hunting. • Biological changes increased hunting efficiency. • H. erectus’ average brain size (1000 cc) is double that of the australopithecines. • Hunting and Gathering • H. erectus’ bipedalism, the--relative to the australopithecines--de-emphasis on chewing (smaller molars), and the emphasis on the front teeth (possibly for eating flesh) all suggest hunting and gathering as its primary adaptive strategy. • The skeletal evidence for hunting and gathering is supported by site remains, such as those found at Terra Amata (approximately 300,000 years ago).
Adaptive Strategies of Homo erectus: Language • No evidence clearly supporting H. erectus’ use of language exists. • Kottak argues that Acheulian tools and apparent, complex hunting techniques, which do exist in the fossil record, support the possibility of rudimentary speech.
The Evolution and Expansion of Homo erectus • Important H. erectus Sites • East, West Turkana, Kenya, dated 1.6 m.y.a. (Leakey). • Upper Bed II, Olduvai, dated 1 m.y.a. • Trinil, Java, Indonesia, dated approximately 700,000 years ago (Dubois). • Zhoukoudian, China (a.k.a. “Peking Man”) is a massive site, dated 500,000-350,000 years ago. • Europe has nonskeletal remains dating 700,000 years ago, and skeletal remains dated at 500,000. • The site of Dmanisi, in the former Soviet Republic of Georgia, has produced two skulls that have been dated to 1.75-1.7 m.y.a. • The vast environmental differences encompassed by the H. erectus sites, and the associated lack of physical variation, attest to the success of culture as an adaptive strategy.
Archaic Homo sapiens • It is likely that the Archaic Homo sapiens population was most concentrated in tropical regions, but thus far more work has been done in Europe. • Archaic Homo sapiens (300,000-35,000 B.P.) includes Homo sapiens neandertalensis (Neandertals, 130,000-35,000 years ago). • The range of Homo sapiens was even more extensive than that of Homo erectus.
The Neandertals • Cold-Adapted Neandertals • The combination of relatively large torso and short limbs, along with large, broad nasal passages, is evidence of adaptation to a cold climate. • Neandertal front teeth were extremely large and the remains of these show evidence of wear. • The face, particularly the large browridge, was designed to support considerable stress on the front teeth (possibly the result of chewing animal hides). • Neandertal cranial capacity was well within (possibly exceeding) the average for H. sapiens (1350 cc). • Later Neandertal remains show a decrease in the robustness of the front teeth and face, suggesting the use of tools (Mousterian) replaced teeth, and suggesting selection against the larger teeth (possibly due to infections in crowded jaws).
TheNeandertals and Modern People • Two basic models attempt to answer the debate about Neandertals’ place in Homo sapiens sapiens ancestry. • Neandertals were fully Homo sapiens, their differences constituting a minor sub-specific variation that disappeared as Neandertals were assimilated into the broader H. sapiens population. • “Replacement Hypothesis”: Neandertals were the product of a split within the H. erectus population, wherein one side moved into northern Europe and became Neandertals, and the other side evolved into Homo sapiens sapiens (AnatomicallyModern Humans--or AMHs) in the Middle East, Africa, or Asia and then drove Neandertals to extinction upon moving into their territories.
TheNeandertals and Modern People • Neandertals differed from AMHs in their comparatively rugged skeletons and faces, huge front teeth, larger cranial capacity, and greater sexual dimorphism. • However, these differences were exaggerated on the basis of a misinterpretation of the La Chapelle-aux-Saints find, which turned out to be the skeleton of an old Neandertal man who had suffered from osteoarthritis. • Current interpretations of the fossil evidence and dating seem to support the replacement hypothesis.
About Eve: Mitochondrial DNA (mtDNA) • Only the mother contributes mtDNA to an offspring, and this occurs through cloning, thus only mutation may change the pattern of mtDNA from one generation to the next. • Researchers from Berkeley generated a computerized model of Homo evolution, based upon the average rate of mutation in known samples of mtDNA. • The model describes an evolutionary tree, at the base of which is a single female, called “Eve,” in sub-Saharan Africa 200,000 B.P., from whom all modern humans have descended.
Evidence Contradicting the “Eve” Hypothesis • Other researchers have identified traits associated with particular geographic ranges that begin before “Eve” and occur continuously in those places across the change from H. erectus to H. sapiens. • The continuity of these traits contradicts the notion that “Eve-based” populations could have moved in and replaced the H. erectus populations in which the traits originated. • This counter-evidence suggests a model wherein many different H. erectus populations evolved into H. sapiens simultaneously, while gene flow ensured that the populations remained conspecific.
Recent DNA Evidence • Recently, researchers have been able to extract Neandertal DNA and compare it to DNA from modern humans. • The research suggests that Neandertals and AMHs were distinct groups that split apart around 600,000 years ago. • This research also indicates that Neandertals died out without leaving a genetic legacy with the AMH populations that eventually displaced them in western Europe.
Multiregional Evolution • The Eve hypothesis argues that a small group of modern humans evolved recently in Africa, then spread out and occupied the rest of the world, replacing the resident H. erectus populations. • The multiregional model for the evolution of modern humans argues that H. erectus evolved into modern H. sapiens in each region (Africa, Europe, Asia, and Australia). • Linked by gene flow, humans in every region could and would share genetic mutations. • If a mutation conferred a substantial selective advantage, it would spread rapidly from one group to all others.
Multiregional Evolution • Dr. Milford Wolpoff is the major proponent of the multiregional evolution model. • Advocates of the multiregional model argue that the fossil record does not support the Eve hypothesis. • The fossil record shows long-term regional continuity rather than an abrupt shift around 200,000 years ago when the Eve supporters date the appearance of modern humans. • Fossils show that certain features have persisted in particular regions for hundreds of thousands of years. • The regional continuity of unique physical features supports the multiregional model.
Advances in Technology • Toolmaking technology shifted from flaking (Mousterian) to the making of blades, which is much more efficient and allows for greater specialization and diversity. • An increase in the distribution and number of technological remains is evidence of an overall increase in Homo’s population. • Tool Diversity • Different tool shapes, in connection with other site remains, can be associated with specific tasks, thus giving evidence as to how ancient human populations fit in their ecological niches. • Some features of tools are not so much related to function as they are to traditions specific to a population.
Glacial Retreat • During the glacial period, large game hunting constituted a major feature in the adaptive strategies of most Homo populations. • Changes Due to Glacial Retreat. • The continental shelf was covered with water, creating a zone for new marine life that was accessible to humans. • Particularly in northern regions, biodiversity increased overall, as the plains of southwestern Europe were replaced by forests. • Broad-spectrum revolution: as a result of the postglacial changes, human populations’ means of exploiting their environments became correspondingly more diverse, setting the stage for food production.
Cave Art • Most cave paintings are concentrated in southwestern France and northern Spain. • Various magical or ritual functions have been proposed as the reason for the cave paintings: ceremonies of increase, improved hunting, rites of passage.
The Mesolithic • The Mesolithic followed the Upper Paleolithic and is also marked by the trends of diversification called the broad-spectrum revolution. • Physical Evidence. • Most known Mesolithic remains are the result of archaeological research done in Europe. • Microliths are small stone tools that are typical of Mesolithic technology: fishhooks, harpoon tips, and dart tips. • The technology reflects the shift from a focus on herd game hunting (since these animals had moved north with glacial retreat) to more varied and specialized activities.
Mesolithic Subsistence • Mesolithic saw the domestication of the dog, the development of food preservation techniques, the spread of the bow and arrow, the development of wood and leather working, and actual carpentry. • Gathering. • “Broad-spectrum” changes caused gathering, rather than hunting, to become the mainstay of human economies. • Based on what we know from comparisons of modern hunting-based societies with hunter-gatherer societies, the role of women in Mesolithic subsistence economies probably increased as gathering became more important.