We discuss the impact of horizontal gene transfer (HGT) on phylogenetic reconstruction and taxonomy. We review the power of HGT as a creative force in assembling new metabolic pathways, and we discuss the impact that HGT has on phylogenetic reconstruction. On one hand, shared derived characters are created through transferred genes that persist in the recipient lineage, either because they were adaptive in the recipient lineage or because they resulted in a functional replacement. On the other hand, taxonomic patterns in (...) microbial phylogenies might also be created through biased gene transfer. The agreement between different molecular phylogenies has encouraged interpretation of the consensus signal as reflecting organismal history or as the tree of cell divisions; however, to date the extent to which the consensus reflects shared organismal ancestry and to which it reflects highways of gene sharing and biased gene transfer remains an open question. Preferential patterns of gene exchange act as a homogenizing force in creating and maintaining microbial groups, generating taxonomic patterns that are indistinguishable to those created by shared ancestry. To understand the evolution of higher bacterial taxonomic units, concepts usually applied in population genetics need to be applied. (shrink)

Danchin argues that if scientists can reach a level of understanding of genomes, they will be able to resolve the major biological puzzle of the 21st century: the enigma of the living machine that creates the living machine.

Continuing his exploration of the organization of complexity and the science of design, this new edition of Herbert Simon's classic work on artificial ...

The book presents a new way of understanding Darwinism and evolution by natural selection, combining work in biology, philosophy, and other fields.

In this classic, the world's expert on language and mind lucidly explains everything you always wanted to know about language: how it works, how children learn it, how it changes, how the brain computes it, and how it evolved. With deft use of examples of humor and wordplay, Steven Pinker weaves our vast knowledge of language into a compelling story: language is a human instinct, wired into our brains by evolution. The Language Instinct received the William James Book Prize from (...) the American Psychological Association and the Public Interest Award from the Linguistics Society of America. This edition includes an update on advances in the science of language since The Language Instinct was first published. (shrink)

Genes and the Agents of Life undertakes to rethink the place of the individual in the biological sciences, drawing parallels with the cognitive and social sciences. Genes, organisms, and species are all agents of life but how are each of these conceptualized within genetics, developmental biology, evolutionary biology, and systematics? The 2005 book includes highly accessible discussions of genetic encoding, species and natural kinds, and pluralism above the levels of selection, drawing on work from across the biological sciences. The book (...) is a companion to the author's Boundaries of the Mind (2004), also available from Cambridge, where the focus is the cognitive sciences. The book will appeal to a broad range of professionals and students in philosophy, biology, and the history of science. You can download the table of contents and the first chapter here. (shrink)

What makes a biological entity an individual? Jack Wilson shows that past philosophers have failed to explicate the conditions an entity must satisfy to be a living individual. He explores the reason for this failure and explains why we should limit ourselves to examples involving real organisms rather than thought experiments. This book explores and resolves paradoxes that arise when one applies past notions of individuality to biological examples beyond the conventional range and presents an analysis of identity and persistence. (...) The book's main purpose is to bring together two lines of research, theoretical biology and metaphysics, which have dealt with the same subject in isolation from one another. Wilson explains an alternative theory about biological individuality which solves problems which cannot be addressed by either field alone. He presents a more fine-grained vocabulary of individuation based on diverse kinds of living things, allowing him to clarify previously muddled disputes about individuality in biology. (shrink)

Striving to boldly redirect the philosophy of science, this book by renowned philosopher Philip Kitcher examines the heated debate surrounding the role of science in shaping our lives. Kitcher explores the sharp divide between those who believe that the pursuit of scientific knowledge is always valuable and necessary--the purists--and those who believe that it invariably serves the interests of people in positions of power. In a daring turn, he rejects both perspectives, working out a more realistic image of the sciences--one (...) that allows for the possibility of scientific truth, but nonetheless permits social consensus to determine which avenues to investigate. He then proposes a democratic and deliberative framework for responsible scientists to follow. Controversial, powerful, yet engaging, this volume will appeal to a wide range of readers. Kitcher's nuanced analysis and authorititative conclusion will interest countless scientists as well as all readers of science--scholars and laypersons alike. (shrink)

ORIGIN OF SPECIES. INTRODUCTION. When on board HMS 'Beagle,' as naturalist, I was ranch struck with certain facts in the distribution of the organic beings ...

Robert Batterman examines a form of scientific reasoning called asymptotic reasoning, arguing that it has important consequences for our understanding of the scientific process as a whole. He maintains that asymptotic reasoning is essential for explaining what physicists call universal behavior. With clarity and rigor, he simplifies complex questions about universal behavior, demonstrating a profound understanding of the underlying structures that ground them. This book introduces a valuable new method that is certain to fill explanatory gaps across disciplines.

Philosophical discussions of species have focused on multicellular, sexual animals and have often neglected to consider unicellular organisms like bacteria. This article begins to fill this gap by considering what species concepts, if any, apply neatly to the bacterial world. First, I argue that the biological species concept cannot be applied to bacteria because of the variable rates of genetic transfer between populations, depending in part on which gene type is prioritized. Second, I present a critique of phylogenetic bacterial species, (...) arguing that phylogenetic bacterial classification requires a questionable metaphysical commitment to the existence of essential genes. I conclude by considering how microbiologists have dealt with these biological complexities by using more pragmatic and not exclusively evolutionary accounts of species. I argue that this pragmatism is not borne of laziness but rather of the substantial conceptual problems in classifying bacteria based on any evolutionary standard. (shrink)

In the course of defending his view of the relation between the special sciences and physics from Jaegwon Kim’s objections Jerry Fodor asks “So then, why is there anything except physics?” By which he seems to mean to ask if physics is fundamental and complete in its domain how can there be autonomous special science laws. Fodor wavers between epistemological and metaphysical understandings of the autonomy of the special sciences. In my paper I draw out the metaphysical construal of his (...) view and argue that while in a sense it answers Fodor’s question it is immensely implausible. (shrink)

Lateral gene transfer, the exchange of genetic information between lineages, not only makes construction of a universal Tree of Life difficult to achieve, but calls into question the utility and meaning of any result. Here I review the science of prokaryotic LGT, the philosophy of the TOL as it figured in Darwin’s formulation of the Theory of Evolution, and the politics of the current debate within the discipline over how threats to the TOL should be represented outside it. We could (...) encourage a more realistic and supportive public understanding of evolution by admitting that what we believe in is not a unified meta-theory but a versatile and well-stocked explanatory toolkit. (shrink)

One of intuitions driving the acceptance of a neat structured tree of life is the assumption that organisms and the lineages they form have somewhat stable spatial and temporal boundaries. The phenomenon of symbiosis shows us that such ‘fixist’ assumptions does not correspond to how the natural world actually works. The implications of lateral gene transfer (LGT) have been discussed elsewhere; I wish to stress a related point. I will focus on lateral function transfer (LFT) and will argue, using examples (...) of what many would call ‘superorganisms’, that the emergence of symbiotic individuals revives the importance of functional and adaptationist thinking in how we conceptualize the lineages of biological individuals. The consequence of the argument is that, if we really want to hold onto tree of life thinking, we had better accept that new saplings appear and disappear all the time. (shrink)

Philosophers of biology, along with everyone else, generally perceive life to fall into two broad categories, the microbes and macrobes, and then pay most of their attention to the latter. ‘Macrobe’ is the word we propose for larger life forms, and we use it as part of an argument for microbial equality. We suggest that taking more notice of microbes – the dominant life form on the planet, both now and throughout evolutionary history – will transform some of the philosophy (...) of biology’s standard ideas on ontology, evolution, taxonomy and biodiversity. We set out a number of recent developments in microbiology – including biofilm formation, chemotaxis, quorum sensing and gene transfer – that highlight microbial capacities for cooperation and communication and break down conventional thinking that microbes are solely or primarily single-celled organisms. These insights also bring new perspectives to the levels of selection debate, as well as to discussions of the evolution and nature of multicellularity, and to neo-Darwinian understandings of evolutionary mechanisms. We show how these revisions lead to further complications for microbial classification and the philosophies of systematics and biodiversity. Incorporating microbial insights into the philosophy of biology will challenge many of its assumptions, but also give greater scope and depth to its investigations. (shrink)

Frequent lateral genetic transfer undermines the existence of a unique “tree of life” that relates all organisms. Vertical inheritance is nonetheless of vital interest in the study of microbial evolution, and knowing the “tree of cells” can yield insights into ecological continuity, the rates of change of different cellular characters, and the evolutionary plasticity of genomes. Notwithstanding within-species recombination, the relationships most frequently recovered from genomic data at shallow to moderate taxonomic depths are likely to reflect cellular inheritance. At the (...) same time, it is clear that several types of ‘average signals’ from whole genomes can be highly misleading, and the existence of a central tendency must not be taken as prima facie evidence of vertical descent. Phylogenetic networks offer an attractive solution, since they can be formulated in ways that mitigate the misleading aspects of hybrid evolutionary signals in genomes. But the connections in a network typically show genetic relatedness without distinguishing between vertical and lateral inheritance of genetic material. The solution may lie in a compromise between strict tree-thinking and network paradigms: build a phylogenetic network, but identify the set of connections in the network that are potentially due to vertical descent. Even if a single tree cannot be unambiguously identified, choosing a subnetwork of putative vertical connections can still lead to drastic reductions in the set of candidate vertical hypotheses. (shrink)

Recently improved understanding of evolutionary processes suggests that tree-based phylogenetic analyses of evolutionary change cannot adequately explain the divergent evolutionary histories of a great many genes and gene complexes. In particular, genetic diversity in the genomes of prokaryotes, phages, and plasmids cannot be fit into classic tree-like models of evolution. These findings entail the need for fundamental reform of our understanding of molecular evolution and the need to devise alternative apparatus for integrated analysis of these genomes. We advocate the development (...) of integrative phylogenomics for analyzing these genomes and their histories, with tools suited to analyzing the importance of lateral gene transfer (LGT) and of DNA evolution in extra-cellular mobile genetic elements (e.g., viruses, plasmids). These phenomena greatly increase the complexity of relationships among interacting genetic partners, as they exchange functional genetic units. We examine the ontology of functional genetic units, interacting genetic partners, and emergent genetic associations, argue that these three categories of entities are required for a successful integrated phylogenomics. We conclude with arguments to suggest that the proposed new perspective and associated tools are suitable, and perhaps required, as a replacement for the bifurcating trees that have dominated evolutionary thinking for the last 150 years. (shrink)