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I came to the field of anthropology under the mentorship of ethnohistorian Harold Hickerson, content to haunt the card catalogs and cavernous stacks of university libraries for early accounts of preagricultural peoples. My treasure hunts were aimed at uncovering glimpses of aboriginal social organization for hunter-gatherers on three continents and documenting postcontact change in these societies over time. The aggregate picture that emerged for foragers in their most pristine state was one of robust communities, diverse systems of kinship, and a broad spectrum of sociopolitical complexity. For most of these societies, however, their vitality and continuity was short-lived. Genocide, disease, atomism, and cultural dismemberment accompanied the unrelenting advance of European colonialism, leaving them depopulated, displaced, and a shadow of their former selves. Ironically, ethnohistorians, in their efforts to reconstruct the cultures of these peoples, often become the unwitting chroniclers of their sorrows.

During the mid to late 1960s, American ethnologists began to reinvent the concept of cultural evolutionism so roundly rejected by their discipline’s founding fathers. Neoevolutionary schemes inevitably commenced with portraits of small, atomistic family bands pursuing a meager living from limited resources in a harsh and unfriendly world. I was struck at the time by the incongruity of memorializing surviving hunter-gatherer societies in these models as living examples of Paleolithic life. Historic foragers, in my mind and experience, were arguably remnant or refugee communities, and unlikely avatars of our ethnographic past. Similarly, the characterization of early human kinship as inevitably male-centered did not square well with what I knew of the ethnohistorical and ethnographic records.

In 1975, I coauthored a book entitled Female of the Species with archaeologist and colleague Barbara Voorhies. An overarching premise of this work was that the human evolutionary journey carries the mark of our primate heritage, but that factors in addition to biology play a major role in shaping the gender behaviors and social institutions of both ancient and modern societies. The book presented the results of a cross-cultural study I completed for over five hundred societies that highlighted how ecology and history have influenced the nature and direction of cultural institutions through time.

During this same period, however, the pendulum had begun to swing toward biological explanations for human social origins and primeval kinship. Sociobiological theory placed primary emphasis on genes, and in particular the male genome, as the engine of human evolutionary development. A broadening schism on questions about early human social life developed between biological and social anthropologists, and it persists to the present day. Their at times intractable nature-nurture debates served to not only bifurcate the discipline into dueling camps, but to partition their respective areas of inquiry. Theories on the nature of early human society were largely co-opted by biological anthropologists. In contrast, their social anthropology counterparts, particularly in Great Britain, remained focused on ethnography and synchronic studies, and in subsequent years even moved away from kinship theory.

About this time, my career path detoured from academia to applied anthropology and public administration. It was not until my retirement about a decade ago that I began to revisit the theoretical questions about the nature of human kinship and our social origins that had so long fascinated me. How were male and female reproductive strategies aligned in the first human families? Were ancient hunter-gatherers cast from a single mold, or did these peoples have diverse economic and social forms? Why have societies throughout most of human history organized themselves into groups based on either uterine or agnatic affiliation? One of the interesting revelations upon returning to academic discourse after a somewhat lengthy hiatus was that these big questions had attracted few new answers. It is almost as if one camp had lost interest in asking them and the other camp felt that they had already been satisfactorily addressed.

In pondering possible reasons for this stalemate, I was struck by the way that the field of anthropology had metamorphosed in recent decades and how these changes have impacted communication and intellectual discourse. Those of us trained by second-generation American anthropologists were expected to attain a working knowledge of the four subfields of the discipline. Not uncommonly, one left graduate school with the ability to pass a laboratory practical exam in human osteology, record the spoken word in phonemic transcription, excavate a five-foot square at a prehistoric midden, and find one’s way around a kinship chart. One could also attend the annual national meetings of the profession and find concurrent sessions in these four basic subdisciplines; meet and academically engage, face-to-face, with more friends than strangers; and even locate the diminutive Margaret Mead on a crowded mezzanine buried at the proximate end of her notorious shepherd’s staff. I believe that this traditional training of anthropologists as generalists in many ways broadened their perspective on the human condition and served to open communication across disparate branches of science.

At the risk of sounding nostalgic, I still have fond memories of lively sit-down discussions and debates with some of anthropology’s great generalists on the subjects of evolution, early human society, and kinship systems. Exchanges with Leslie A. White, George Peter Murdock, Elman Service, Marvin Harris, Eleanor “Happy” Leacock, and Ward Goodenough did not always end in agreement, but always left me with a sense of awe about their breadth of knowledge, their openness to ideas, and their perpetual sense of wonder. Their voices, although past, still resonate, and have found their way into this book.

The age of generalist perspectives within the discipline, however, has been substantially diminished. We have moved from a community of generalists to a community of specialists. Whereas in years past professional anthropologists organized themselves into just a handful of subdisciplinary associations and related journals, today’s American Anthropological Association lists some fifty specialized sections and interest groups with focused memberships, and over twenty-five separate publications. This proliferation of specialized research foci, while perhaps a natural product of the discipline’s growth, also tends to create academic silos that both isolate and insulate their memberships. The trend toward increasing compartmentalization does not bode well for the cross-pollination of ideas. Is anthropology doomed to intellectual myopia and linear thinking?

Two hopeful countertrends provide a potential antidote to long-standing theoretical divides, such as that existing between biological and social anthropologists. First is the wellspring of new cross-disciplinary information that has become available since this debate began. Significant findings are emanating from the fields of primatology, paleontology, geology, paleoecology, genetics, and neuroscience that call for the reconsideration and modification of existing evolutionary theory. It turns out that while some of us were not looking, these parallel bodies of science were addressing many of the same big questions about human evolution, but from different vantage points. These alternative conceptual frameworks are adding key pieces to the puzzle of human origins and human sociality. We need only look. A second positive development is the sea change that has occurred in information technology. Over a relatively short span of time, we have graduated from a universe of typewriters, landlines, mimeographs, paper manuscripts, snail mail, and physical data repositories to personal computers, cell phones, the internet, email, electronic data files, the cloud, e-books, and virtual libraries. Thanks to the digital revolution, scholars of today have literally at their fingertips the ability to not only access an unlimited range of scientific data from their own and other disciplines, but to dialogue with other researchers, some of whom they may never meet, on questions of mutual interest. This is a powerful antidote to linear thinking, and presents both the means and the opportunity to usher in a new generation of generalists.

I have pursued the present work in this spirit. Over the past four years, I have read scores of books and literally hundreds of scholarly journal articles across multiple scientific disciplines. This diverse literature addresses a broad range of questions on hominin evolution and human sociality. The specialized technical data and scientific jargon in many of these sources were admittedly challenging, and some analyses were more difficult to digest than others. But the further along I got on this fascinating journey, the more apparent it became that the nature-nurture controversy in evolutionary theory presents a false dichotomy. New scientific findings inform the social anthropologist that human societies reflect our primate genomic heritage, including not only reproductive behaviors, but how hominid communities have been shaped in similar ways by selective factors in the environment. These findings also inform the biological anthropologist that genes are not the whole story. Their phenotypic expression is influenced by social learning throughout an organism’s lifetime. Recent evidence further suggests that phenotypic traits shaped by culture are at least partially heritable and therefore may have played an important role in the pace and direction of human evolution. In short, those who maintain that the human saga has been directed either by the genome or by culture alone are only half right. It is their interface—their complex, synergistic, and dynamic interaction—that accounts for the origins and trajectory of our genus.

Social DNA proposes to peel back the layers of nested hypotheses underlying popular theories on how our species evolved. It examines their interlocking assumptions about male and female natures, mating and intersexual dominance, Pliocene ecology, subsistence and family provisioning, and the extent to which contemporary primates may be taken as avatars of ancient social life. This book systematically disassembles these layers, evaluates the assumptions on which they are based, considers new or competing evidence, and develops alternative hypotheses that lead to novel reconstructions of human sociality.

This analysis is divided into three major parts. The first examines alternative perspectives on the nature of male and female Pliocene apes and how their mating and feeding patterns may have shaped early social groups. New climate and paleontological data are presented that connects early human occupation sites with more humid waterside habitats, greater resource densities, and evidence of dietary breadth, including reliance on aquatic flora and fauna. This reframing of Plio-Pleistocene ecology has profound implications for ancient social life, particularly when such variation in resource distributions is compared with social patterns observed among nonhuman primates. The second part of the book is devoted to a discussion of signature traits shared by members of both ancient and modern hominin lineages that distinguish them from contemporary apes, such as behavioral plasticity, dietary breadth and food sharing, social demography, and cognitive function. Social DNA entertains the notion that traditional academic emphases on phylogenetic chronologies, material culture, and gross brain or neocortex size has led to an underestimation of ancient hominin ingenuity, intelligence, and social complexity. A central theme of this discussion is that early hominins were, in some ways, like every other primate, but like no other primate. That is, while primates respond in similar ways to similar environmental cues, there are important threshold differences. Contemporary nonhuman species have evolved as specialists, bound by genetic platforms geared to specific niches, whereas hominins evolved as generalists who came equipped with a more diversified gene-culture playbook that broadened their ecological range.

The final section of this book returns to seminal questions about the essence of human kinship. It challenges current theories that tie kinship systems to innate dominance patterns, evolutionary stages, monotypic biograms, or phylogenetic continuity with chimpanzee-like apes. Instead, it proposes that the nature of human kinship systems is not preordained, but rather is the phenotypic expression of epigenetic rules (“social DNA”) that optimize the procurement and allocation of fitness-related resources in a given niche. Characteristic patterns of social group formation based on kinship alliance reflect rules for the regulation and distribution of resources critical to survival, such as energy, materials, genes, and information, that are adaptive in specific ecological settings. Matrilineal and patrilineal kinship systems are understood as variable social technologies for niche construction, with distinct architectures for structuring reproduction, labor, and political groups in relation to available resources.

Social DNA is distinguished from other titles on human evolution in its scope of inquiry. New cross-disciplinary research findings are brought to bear on fundamental questions about the nature of Pliocene ecology, Pleistocene subsistence activities, hominin brain evolution, hominin life history changes, and the relationship of inclusive fitness to primeval kinship systems. It is my hope that this book provides a fresh perspective on our biosocial origins and responds to current calls for the creation of an enhanced dialogue across academic and disciplinary boundaries.

I would like to extend special thanks to archaeologist Jon Erlandson, who graciously read and offered comments on parts of this manuscript. The ideas in this book are my own, but have benefitted from his insights on Pleistocene adaptations and the potential role played by aquatic resources in early human societies. Thanks are also due to my anonymous reviewers, who pointed out errors and omissions in the draft manuscript, and whose constructive comments resulted in improvements to this book. I’d also like to acknowledge ethnologist Isabelle Clark-Deces, who provided encouragement at the onset of this effort, and who left us all too soon.

I am grateful to paleoartists Mauricio Anton and Emiliano Troco for agreeing to share their wonderful portraits of early hominins to illustrate this book, and to artist and friend Drew Fagan for his creative genius, technical support, and good humor throughout this project.

Finally, I would like to thank my editors at Berghahn Books, Harry Eagles and Elizabeth Martinez, for their responsiveness and support during the book’s review and production.