Evolutionary Anthropology Issues News and Reviews

The species Homo heidelbergensis is central to many discussions about recent human evolution. For some workers, it was the last common ancestor for the subsequent species Homo sapiens and Homo neanderthalensis; others regard it as only a European form, giving rise to the Neanderthals. Following the impact of recent genomic studies indicating hybridization between modern humans and both Neanderthals and "Denisovans", the status of these as separate taxa is now under discussion. Accordingly, clarifying the status of Homo heidelbergensis is fundamental to the debate about modern human origins.

The answer to the proffered question, "What is a species?" is considered one of the fundamental issues of biological science, as well as one of the most polarizing and sometimes acrimonious problems. Dozens of species concepts have been defined, but none are universal for implementation across all taxa. Within the past thirty years, the ability to analyze DNA data has progressed to the point that multiple methodologies can be simultaneously applied to the same evolutionary questions. The use of restriction fragment length polymorphisms, microsatellites, and mitochondrial (mtDNA) and nuclear DNA (nucDNA) sequence data has unarguably changed how we look at diversity and intensified the concept debate through the proliferation of species descriptions. Over the past two decades, Madagascar's biodiversity has gone through a tremendous taxonomic expansion by the elevation of subspecies to species and through novel descriptions, especially within the nocturnal lemurs. With the tremendous continuous loss of habitat, exponential human population growth, and stochastic changes predicted over coming decades, elucidating the earth's biodiversity will never be more important than now. Here, we examine species concepts and their attendant criteria. We predict how technological advances will alter, improve and, we hope, fully consolidate the unity of thoughts related to this central topic of evolutionary biology and its numerous interconnected disciplines.

The production of purposefully fractured stone tools with functional, sharp cutting edges is a uniquely derived hominin adaptation. In the long history of life on earth, only hominins have adopted this remarkably expedient and broadly effective technological strategy. In the paleontological record, flaked stone tools are irrefutable proof that hominins were present at a particular place and time. Flaked stone tools are found in contexts ranging from the Arctic to equatorial rainforests and on every continent except Antarctica. Paleolithic stone tools show complex patterns of variability, suggesting that they have been subject to the variable selective pressures that have shaped so many other aspects of hominin behavior and morphology. There is every reason to expect that insights gained from studying stone tools should provide vital and important information about the course of human evolution. And yet, one senses that archeological analyses of Paleolithic stone tools are not making as much of a contribution as they could to the major issues in human origins research.

The Omo-Turkana Basin, including the hominin fossil sites around Lake Turkana and the sites along the lower reaches of the Omo River, has made and continues to make an important contribution to improving our murky understanding of human evolution. This review highlights the various ways the Omo-Turkana Basin fossil record has contributed to, and continues to challenge, interpretations of human evolution. Despite many diagrams that look suspiciously like comprehensive hypotheses about human evolutionary history, any sensible paleoanthropologist knows that the early hominin fossil record is too meager to do anything other than offer very provisional statements about hominin taxonomy and phylogeny. If history tells us anything, it is that we still have much to learn about the hominin clade. Thus, we summarize the current state of knowledge of the hominin species represented at the Omo-Turkana Basin sites. We then focus on three specific topics for which the fossil evidence is especially relevant: the origin and nature of Paranthropus; the origin and nature of early Homo; and the ongoing debate about whether the pattern of human evolution is more consistent with speciation by cladogenesis, with greater taxonomic diversity or with speciation by anagenetic transformation, resulting in less taxonomic diversity and a more linear interpretation of human evolutionary history.

In 1871, Darwin famously opined, "In each great region of the world the living mammals are closely related to the extinct species of the same region. It is therefore probable that Africa was formerly inhabited by extinct apes closely allied to the gorilla and chimpanzee; and as these two species are now man's nearest allies, it is somewhat more probable that our early progenitors lived on the African continent than elsewhere." Although this quote is frequently recalled today, Darwin's next line is rarely acknowledged: "But it is useless to speculate on this subject, for an ape nearly as large as a man, namely the Dryopithecus of Lartet, which was closely allied to the anthropomorphous Hylobates, existed in Europe during the Upper Miocene period; and since so remote a period the earth has certainly undergone many great revolutions, and there has been ample time for migration on the largest scale."

The peculiar mammalian fauna that inhabited Afro-Arabia during the Paleogene first came to the attention of the scientific community in the early part of the twentieth century, when Andrews1 and Schlosser2 published their landmark descriptions of fossil mammals from the Fayum Depression in northern Egypt. Their studies revealed a highly endemic assemblage of land mammals that included the first known Paleogene records of hyraxes, proboscideans, and anthropoid primates, but which lacked ancestors of many iconic mammalian lineages that are found in Africa today, such as rhinos, zebras, bovids, giraffes, and cats. Over the course of the last century, the Afro-Arabian Paleogene has yielded fossil remains of several other endemic mammalian lineages,3 as well as a diversity of prosimian primates,4 but we are only just beginning to understand how the continent's faunal composition came to be, through ancient processes such as the movement of tectonic plates, changes in climate and sea level, and early phylogenetic splits among the major groups of placental mammals. These processes, in turn, made possible chance dispersal events that were critical in determining the competitive landscape-and, indeed, the survival-of our earliest anthropoid ancestors. Newly discovered fossils indicate that the persistence and later diversification of Anthropoidea was not an inevitable result of the clade's competitive isolation or adaptive superiority, as has often been assumed, but rather was as much due to the combined influences of serendipitous geographic conditions, global cooling, and competition with a group of distantly related extinct strepsirrhines with anthropoid-like adaptations known as adapiforms. Many of the important details of this story would not be known, and could never have been predicted, without the fossil evidence that has recently been unearthed by field paleontologists. © 2012 Wiley Periodicals, Inc.

There were at least four waves of bow and arrow use in northern North America. These occurred at 12000, 4500, 2400, and after about 1300 years ago. But to understand the role of the bow and arrow in the north, one must begin in the eighteenth century, when the Russians first arrived in the Aleutian Islands. At that time, the Aleut were using both the atlatl and dart and the bow and arrow (Fig. ). This is significant for two particular and important reasons. First, there are few historic cases in which both technologies were used concurrently; second, the bow and arrow in the Aleutian Islands were used almost exclusively in warfare. The atlatl was a critical technology because the bow and arrow are useless for hunting sea mammals. One cannot launch an arrow from a kayak because it is too unstable and requires that both hands remain on a paddle. To use an atlatl, it is necessary only to stabilize the kayak with a paddle on one side and launch the atlatl dart with the opposite hand. The Aleut on the Alaska Peninsula did indeed use the bow and arrow to hunt caribou there. However, in the 1,400 km of the Aleutian Islands, there are no terrestrial mammals except humans and the bow was reserved almost exclusively for conflicts among them. The most significant event in the history of the bow and arrow is not its early introduction, but rather the Asian War Complex 1300 years ago, when the recurve and backed bows first entered the region, altering regional and hemispheric political dynamics forever. Aleut male as shown in Liapunova Figure 2, remastered and edited by Maschner. A) Atlatl and darts, B) the recurved bow, C) armor, and D) shield. Drawing by M. C. Levashov, 1764–1769, original in the Central State Archives of the Navy, Russia. image

This paper has several interconnected goals. First and most generally, we will review the project represented by the papers in this dedicated issue and the SAA Symposium (2012) on Social Complexity and the Bow. This project centers on the ever-stronger and broader theory testing now becoming feasible in archeology and anthropology, in this case exploiting the unique natural laboratory represented by what we refer to as the North American Neolithic transitions. Second, we will strive to synopsize the papers in this issue as opportunities to falsify two general theories of the cause of increases in social complexity associated with the North American Neolithic: warfare and social coercion theories.(1) We argue that, though much work remains to be done, the current evidence supports one of the central predictions of both these theories, that the local arrival of elite bow technology was a central driver of local transitions to increased social complexity. This conclusion, if ultimately verified, has profound implications for the possibility of general theories of history. Third, we will argue that several important details of this evidence falsify warfare theory and support (fail to falsify) social coercion theory (the authors' favored perspective). Moreover, several potential falsifications of social coercion theory are amenable to alternative interpretations, leading to new falsifiable predictions. Finally, we discuss how interactions with our colleagues in this project produced new insights into several details of the predictions of social coercion theory, improving our interpretative capacity.

The bow more than doubled, likely tripled, the success of individuals bent on killing animal or human targets (Box ). The advent of this revolutionary technology generated different responses in western North America depending on subsistence and sociopolitical organization at the time of its arrival, roughly 2300 - 1300 B.P. Its effect was substantial in California and the Great Basin, particularly on group size, which in many places diminished as a consequence of the bow's reliability. The counter-intuitive result was to increase within group-relatedness enough to encourage intensification of plant resources, previously considered too costly. The bow rose to greatest direct economic importance with the arrival of the horse, and was put to most effective use by former Great Basin groups who maintained the family band system that had developed around intensive Great Basin plant procurement, adapting the same organization to a lifestyle centered on the equestrian pursuit of buffalo and warfare.

As recently as the 1980s, archeologists focusing on prehistoric eastern North America paid little attention to intergroup conflict. Today the situation is quite different, as indicated by this Special Issue. Archeologists now face three principal challenges: to document the temporal and spatial distribution of evidence of conflict; to identify the cultural and environmental conditions associated with variation in the nature and frequency of warfare over long periods of time and large geographical areas; and to determine the extent to which intergroup tensions contributed to or resulted from changes in sociopolitical complexity, economic systems, and population size and distribution. We present data from habitation and mortuary sites in the Eastern Woodlands, notably the midcontinent, that touch on all three issues. Palisaded sites and victims of attacks indicate the intensity of conflicts varied over time and space. Centuries-long intervals of either high or low intergroup tensions can be attributed to an intensification or relaxation of pressure on resources that arose in several ways, such as changes in local population density; technological innovations, including subsistence practices; and the natural environment.