The eukaryotic genome is a mosaic of eubacterial and archaeal genes in addition to those unique to itself. The mosaic may have arisen as the result of two prokaryotes merging their genomes, or from genes acquired from an endosymbiont of eubacterial origin. A third possibility is that the eukaryotic genome arose from successive events of lateral gene transfer over long periods of time. This theory does not exclude the endosymbiont, but questions whether it is necessary to explain the peculiar set (...) of eukaryotic genes. We use phylogenetic studies and reconstructions of ancestral first appearances of genes on the prokaryotic phylogeny to assess evidence for the lateral gene transfer scenario. We find that phylogenies advanced to support fusion can also arise from a succession of lateral gene transfer events. Our reconstructions of ancestral first appearances of genes reveal that the various genes that make up the eukaryotic mosaic arose at different times and in diverse lineages on the prokaryotic tree, and were not available in a single lineage. Successive events of lateral gene transfer can explain the unusual mosaic structure of the eukaryotic genome, with its content linked to the immediate adaptive value of the genes its acquired. Progress in understanding eukaryotes may come from identifying ancestral features such as the eukaryotic splicesome that could explain why this lineage invaded, or created, the eukaryotic niche. BioEssays 28:57–64, 2006. © 2005 Wiley Periodicals, Inc. (shrink)

Divided into three parts, this book's purpose, as given in the introduction, is to consider whether or not man is descended from a pre-existing form, his manner ...

In this paper, I argue that the adaptive fit between human cultures and their environment is persuasive evidence that some form of evolutionary mechanism has been important in driving human cultural change. I distinguish three mechanisms of cultural evolution: niche construction leading to cultural group selection; the vertical flow of cultural information from parents to their children, and the replication and spread of memes. I further argue that both cultural group selection and the vertical flow of cultural information have been (...) important. More conjecturally, I identify a potential role for meme-based cultural evolution in the explanation of the ‘human revolution’ of the last 100 000 or so years, and defuse an important objection to that explanation. Introduction Cultural groups The cultural invention of adaptive complexes Niche construction models Dual inheritance Memes Memes or minds? Conclusion. (shrink)

The drive to describe cultural history as an evolutionary process has two sources. One from within social theory is part of the impetus to convert social studies into "social sciences" providing them with the status accorded to the natural sciences. The other comes from within biology and biological anthropology in the belief that the theory of evolution must be universal in its application to all functions of all living organisms. The social scientific theory of cultural evolution is pre-Darwinian, employing a (...) developmental model of unfolding characterized by intrinsic directionality, by definable stages that succeed each other and by some criterion of progress. It is arbitrary in its definitions of progress and has had the political problem that a diachronic claim of cultural progress implies a synchronic differential valuation of present-day cultures. The biological scheme creates an isomorphism between the Darwinian mechanism of evolution and cultural history, postulating rules of cultural "mutation", cultural inheritance and some mechanism of natural selection among cultural alternatives. It uses simplistic ad hoc notions of individual acculturation and of the differential survival and reproduction of cultural elements. It is unclear what useful work is done by substituting the metaphor of evolution for history. (shrink)

The present edition provides a detailed and accessible discussion ofhis theories and adds an account of the immediate responses to the book on publication.

Joseph Henrich and Richard McElreath begin their survey of theories of cultural evolution with a striking historical example. They contrast the fate of the Bourke and Wills expedition — an attempt to explore some of the arid areas of inland Australia — with the routine survival of the local aboriginals in exactly the same area. That expedition ended in failure and death, despite the fact that it was well equipped, and despite the fact that those on the expedition were tough (...) and experienced. For survival in such areas depended on accumulated local knowledge. The locals had learned how detoxify seeds before making bread from them, and how to catch the local fish. Bourke and Wills and their companions lacked this local knowledge, and died as a result (Henrich and McElreath 2003). (shrink)

In this paper I argue, first, that human lifeways depend on cognitive capital that has typically been built over many generations. This process of gradual accumulation produces an adaptive fit between human agents and their environments; an adaptive fit that is the result of hidden‐hand, evolutionary mechanisms. To explain distinctive features of human life, we need to understand how cultures evolve. Second, I distinguish a range of different evolutionary models of culture. Third, I argue that none of meme‐based models, dual (...) inheritance models, nor Boyd and Richerson's models fully succeed in explaining this adaptive fit between agent and the world. I then briefly develop an alternative. Finally, I explore (in a preliminary way) constraints on cultural adaptation. The processes of cultural evolution sometimes built a fit between agents and their environment, but they do not always do so. Why is folk medicine, for example, so much less reliable than folk natural history? (shrink)

Darwinizing culture: the status of memetics as a science pits leading intellectuals, against each other to battle it out, in this, the first debate over 'memes'. With a foreword by Daniel Dennett, and contributions from Dan Sperber, David Hull, Robert Boyd, Susan Blackmore, Henry Plotkin, and others, the result is a thrilling and challenging debate that will perhaps mark a turning point for the field, and for future research.

Biology and the social sciences share an interest in phylogeny. Biologists know that living species are descended from past species, and use the pattern of similarities among living species to reconstruct the history of phylogenetic branching. Social scientists know that the beliefs, values, practices, and artifacts that characterize contemporary societies are descended from past societies, and some social science disciplines, linguistics and cross cultural anthropology for example, have made use of observed similarities to reconstruct cultural histories. Darwin appreciated that his (...) theory of descent with modification had many similarities of pattern and process to the already well developed field of historical linguistics. In many other areas of social science, however, phylogenetic reconstruction has not played a central role. (shrink)

Numerous scenarios explain the origin of the eukaryote cell by fusion or endosymbiosis between an archaeon and a bacterium (and sometimes a third partner). We evaluate these hypotheses using the following three criteria. Can the data be explained by the null hypothesis that new features arise sequentially along a stem lineage? Second, hypotheses involving an archaeon and a bacterium should undergo standard phylogenetic tests of gene distribution. Third, accounting for past events by processes observed in modern cells is preferable to (...) postulating unknown processes that have never been observed. For example, there are many eukaryote examples of bacteria as endosymbionts or endoparasites, but none known in archaea. Strictly post‐hoc hypotheses that ignore this third criterion should be avoided. Applying these three criteria significantly narrows the number of plausible hypotheses. Given current knowledge, our conclusion is that the eukaryote lineage must have diverged from an ancestor of archaea well prior to the origin of the mitochondrion. Significantly, the absence of ancestrally amitochondriate eukaryotes (archezoa) among extant eukaryotes is neither evidence for an archaeal host for the ancestor of mitochondria, nor evidence against a eukaryotic host. BioEssays 29: 74–84, 2007. © 2006 Wiley Periodicals, Inc. (shrink)

Discussions of the theory and practice of systematics and evolutionary biology have heretofore revolved around the views of philosophers of science. I reexamine these issues from the different perspective of the philosophy of history. Just as philosophers of history distinguish between chronicle (non-interpretive or non-explanatory writing) and narrative history (interpretive or explanatory writing), I distinguish between evolutionary chronicle (cladograms, broadly construed) and narrative evolutionary history. Systematics is the discipline which estimates the evolutionary chronicle. ¶ Explanations of the events described in (...) the evolutionary chronicle are not of the covering-law type described by philosophers of science, but rather of the how-possibly, continuous series, and integrating types described by philosophers of history. Pre-evolutionary explanations of states (in contrast to chroniclar events) are still widespread in "evolutionary" biology, however, because evolutionary chronicles are in general poorly known. To the extent that chronicles are known, the narrative evolutionary histories based on them are structured like conventional historical narratives, in that they treat their central subjects as ontological individuals. This conventional treatment is incorrect. The central subjects of evolutionary narratives are clades, branched entities which have some of the properties of individuals and some of the properties of classes. Our unconscious treatment of the subjects of evolutionary narratives as individuals has been the cause of erroneous notions of progress in evolution, and of views that taxa "develop" ontogenetically in ways analogous to individual organisms. We must rewrite our narrative evolutionary histories so that they properly represent the branching nature of evolution, and we must reframe our evolutionary philosophies so that they properly reflect the historical nature of our subject. (shrink)

The next time you get sick, consider this before picking up the aspirin: your body may be doing exactly what it's supposed to. In this ground-breaking book, two pioneers of the science of Darwinian medicine argue that illness as well as the factors that predispose us toward it are subject to the same laws of natural selection that otherwise make our bodies such miracles of design. Among the concerns they raise: When may a fever be beneficial? Why do pregnant women (...) get morning sickness? How do certain viruses "manipulate" their hosts into infecting others? What evolutionary factors may be responsible for depression and panic disorder? Deftly summarizing research on disorders ranging from allergies to Alzheimer's, and form cancer to Huntington's chorea, Why We Get Sick, answers these questions and more. The result is a book that will revolutionize our attitudes toward illness and will intrigue and instruct lay person and medical practitioners alike. (shrink)

Significant amounts of wealth have been exchanged as part of marriage settlements throughout history. Although various models have been proposed for interpreting these practices, their development over time has not been investigated systematically. In this paper we use a Bayesian MCMC phylogenetic comparative approach to reconstruct the evolution of two forms of wealth transfers at marriage, dowry and bridewealth, for 51 Indo-European cultural groups. Results indicate that dowry is more likely to have been the ancestral practice, and that a minimum (...) of four changes to bridewealth is necessary to explain the observed distribution of the two states across the cultural groups. (shrink)