Transforming Our Thinking about Transitional Forms

A common misconception of evolutionary biology is that it involves a search for “missing links” in the history of life. Relying on this misconception, antievolutionists present the supposed absence of transitional forms from the fossil record as evidence against evolution. Students of biology need to understand that evolution is a branching process, paleontologists do not expect to find “missing links,” and evolutionary research uses independent lines of evidence to test hypotheses and make conclusions about the history of life. Teachers can facilitate such learning by incorporating cladistics and tree-thinking into the curriculum and using evograms to focus on important evolutionary transitions.     

“Force-Talk” in Evolutionary Explanation: Metaphors and Misconceptions

The notion of “pressure” as an evolutionary “force” that “causes” evolution is a pervasive linguistic feature of biology textbooks, journal articles, and student explanatory discourse. We investigated the consequences of using a textbook and curriculum that incorporate so-called force-talk. We examined the frequency with which biology majors spontaneously used notions of evolutionary “pressures” in their explanations, students’ definitions and explanations of what they meant when they used pressures, and the structure of explanatory models that incorporated evolutionary pressures and forces. We found that 12–20 percent of undergraduates spontaneously used “pressures” and/or “forces” as explanatory factors but significantly more often in trait gain scenarios than in trait loss scenarios. The majority of explanations using “force-talk” were characterized by faulty evolutionary reasoning. We discuss the conceptual similarity between faulty notions of evolutionary pressures and linguists’ force-dynamic models of everyday reasoning and ultimately question the appropriateness of force-talk in evolution education.     

Don’t Call it “Darwinism”

Evolutionary biology owes much to Charles Darwin, whose discussions of common descent and natural selection provide the foundations of the discipline. But evolutionary biology has expanded well beyond its foundations to encompass many theories and concepts unknown in the 19th century. The term “Darwinism” is, therefore, ambiguous and misleading. Compounding the problem of “Darwinism” is the hijacking of the term by creationists to portray evolution as a dangerous ideology—an “ism”—that has no place in the science classroom. When scientists and teachers use “Darwinism” as synonymous with evolutionary biology, it reinforces such a misleading portrayal and hinders efforts to present the scientific standing of evolution accurately. Accordingly, the term “Darwinism” should be abandoned as a synonym for evolutionary biology.     

Evolutionary Morphology in Belgium

In historical literature, Edouard van Beneden (1846–1910) is mostly remembered for his cytological discoveries. Less well known, however, is that he also introduced evolutionary morphology – and indeed evolutionary theory as such – in the Belgian academic world. The introduction of this research programme cannot be understood without taking both the international and the national context into account. It was clearly the German example of the Jena University that inspired van Beneden in his research interests. The actual launch of evolutionary morphology at his University of Liège was, however, also connected with the dynamic of Belgian university reforms and the local rationale of creating a research “school.” Thanks to his networks, his mastering of the rhetoric of the “new” biology, his low ideological profile and his capitalising on the new academic élan in late-19th century Belgium, van Beneden managed to turn his programme into a local success from the 1870s onwards. Two decades later, however, the conceptual underpinnings of evolutionary morphology came under attack and the “Van Beneden School” lost much of its vitality. Despite this, van Beneden’s evolutionary morphology was prototypical for the research that was to come. He was one of the first scientific heavyweights in Belgium to turn the university laboratory into a centre of scientific practice and the hub of a research school.     

Abnormal births and other “ill omens”

We summarize the ethnographic literature illustrating that “abnormal birth” circumstances and “ill omens” operate as cues to terminate parental investment. A review of the medical literature provides evidence to support our assertion that ill omens serve as markers of biological conditions that will threaten the survival of infants. Daly and Wilson (1984) tested the prediction that children of demonstrably poor phenotypic quality will be common victims of infanticide. We take this hypothesis one stage further and argue that some children will be poor vehicles for parental investment yet are not of demonstrably poor quality at birth. We conclude that when people dispose of infants due to “superstitious beliefs” they are pursuing an adaptive strategy in eliminating infants who are poor vehicles for parental investment. Catherine Hill lectures in biological anthropology/human sciences at Durham University’s University College, Stockton. She trained in biological anthropology at University College, London. Her current research interests include human and nonhuman primate socioecology and human resource ecology and development issues. Helen Ball lectures in biological anthropology/human sciences at Durham University’s University College, Stockton. She trained in biological anthropology at the University of Massachusetts at Amherst. Her current research interests include nonhuman primate behavior and socioecology, reproductive biology, and evolutionary issues.     

Effects of Quaternary Climatic Change on Speciation in Mammals

An ongoing controversy in evolutionary biology is the extent to which climatic changes drive evolutionary processes. On the one hand are “Red Queen” hypotheses, which maintain that climatic change is less important than biotic interactions in causing evolutionary change. On the other hand are “Court Jester” models, which recognize climatic change as a very important stimulus to speciation. The Quaternary Period (the last 1.8 million years), characterized by multiple climatic changes in the form of glacial–interglacial transitions, offers a fertile testing ground for ascertaining whether cyclical climatic changes that operate at the 100,000-year time scale appreciably influence evolutionary patterns in mammals. Despite the increased potential for isolation of populations that should occur with multiple advances and retreats of glaciers and rearrangement of climatic zones, empirical data suggests that speciation rates were neither appreciably elevated for Quaternary mammals, nor strongly correlated with glacial–interglacial transitions. Abundant evidence attests to population-level changes within the Quaternary, but these did not usually lead to the origin of new species. This suggests that if climatic change does influence speciation rates in mammals, it does so over time scales longer than a typical glacial–interglacial cycle.     

The Evolution of Language: A Comparative Review

For many years the evolution of language has been seen as a disreputable topic, mired in fanciful “just so stories” about language origins. However, in the last decade a new synthesis of modern linguistics, cognitive neuroscience and neo-Darwinian evolutionary theory has begun to make important contributions to our understanding of the biology and evolution of language. I review some of this recent progress, focusing on the value of the comparative method, which uses data from animal species to draw inferences about language evolution. Discussing speech first, I show how data concerning a wide variety of species, from monkeys to birds, can increase our understanding of the anatomical and neural mechanisms underlying human spoken language, and how bird and whale song provide insights into the ultimate evolutionary function of language. I discuss the “descended larynx” of humans, a peculiar adaptation for speech that has received much attention in the past, which despite earlier claims is not uniquely human. Then I will turn to the neural mechanisms underlying spoken language, pointing out the difficulties animals apparently experience in perceiving hierarchical structure in sounds, and stressing the importance of vocal imitation in the evolution of a spoken language. Turning to ultimate function, I suggest that communication among kin (especially between parents and offspring) played a crucial but neglected role in driving language evolution. Finally, I briefly discuss phylogeny, discussing hypotheses that offer plausible routes to human language from a non-linguistic chimp-like ancestor. I conclude that comparative data from living animals will be key to developing a richer, more interdisciplinary understanding of our most distinctively human trait: language.     

Blogging Evolution

A weblog (“blog”) is an publication on the WorldWideWeb in which brief entries are displayed in date order, much like a diary or journal. I describe the general characteristics of blogs, contrasting blogs with other of WWW formats for self-publishing. I describe four categories for blogs about evolutionary biology: “professional,” “amateur,” “apostolic,” and “imaginative.” I also discuss blog networks. I identify paradigms of each category. Throughout, I aim to illuminate blogs about evolutionary biology from the point of view of a user looking for information about the topic. I conclude that blogs are not the best type of source for systematic and authoritative information about evolution, and that they are best used by the information-seeker as a way of identifying what issues are of interest in the community of evolutionists and for generating research leads or fresh insights on one’s own work.

Human neuropsychology and the concept of culture

American anthropology is distinguished by a four-fields approach in which biological, cultural, archaeological, and linguistic dimensions of behavior are examined in evolutionary and cross-cultural perspective. Nevertheless, assumptions of mind-body dualism pervade scholarly thinking in anthropology and have prevented the development of a truly integrated science of human experience. This dualism is most exemplified by the lack of consideration of the role of the brain in both “physical” and “mental” processes, including phenomena labeled as cultural. In this paper, I review neural mechanisms of learning, communication, and emotion, and discuss the implications of these findings for culture theory. Lee Xenakis Blonder is an assistant professor in the Department of Behavioral Science and the Sanders-Brown Center on Aging, University of Kentucky Medical School, Lexington. She is currently examining the effects of stroke in different regions of the brain on language, nonverbal communication, and emotional processing in an attempt to better understand human brain and behavior relations. Recent publications include “Neuropsychological Functioning in Hemiparkinsonism” (with R. E. Gur, R. C. Gur, A. J. Saykin, and H. I. Hurtig),Brain and Cognition 9:244–257 (1989).     

Explaining how and explaining why: developmental and evolutionary explanations of dominance

There have been two different schools of thought on the evolution of dominance. On the one hand, followers of Wright [Wright S. 1929. Am. Nat. 63: 274–279, Evolution: Selected Papers by Sewall Wright, University of Chicago Press, Chicago; 1934. Am. Nat. 68: 25–53, Evolution: Selected Papers by Sewall Wright, University of Chicago Press, Chicago; Haldane J.B.S. 1930. Am. Nat. 64: 87–90; 1939. J. Genet. 37: 365–374; Kacser H. and Burns J.A. 1981. Genetics 97: 639–666] have defended the view that dominance is a product of non-linearities in gene expression. On the other hand, followers of Fisher [Fisher R.A. 1928a. Am. Nat. 62: 15–126; 1928b. Am. Nat. 62: 571–574; Bürger R. 1983a. Math. Biosci. 67: 125–143; 1983b. J. Math. Biol. 16: 269–280; Wagner G. and Burger R. 1985. J. Theor. Biol. 113: 475–500; Mayo O. and Reinhard B. 1997. Biol. Rev. 72: 97–110] have argued that dominance evolved via selection on modifier genes. Some have called these “physiological” versus “selectionist,” or more recently [Falk R. 2001. Biol. Philos. 16: 285–323], “functional,” versus “structural” explanations of dominance. This paper argues, however, that one need not treat these explanations as exclusive. While one can disagree about the most likely evolutionary explanation of dominance, as Wright and Fisher did, offering a “physiological” or developmental explanation of dominance does not render dominance “epiphenomenal,” nor show that evolutionary considerations are irrelevant to the maintenance of dominance, as some [Kacser H. and Burns J.A. 1981. Genetics 97: 639–666] have argued. Recent work [Gilchrist M.A. and Nijhout H.F. 2001. Genetics 159: 423–432] illustrates how biological explanation is a multi-level task, requiring both a “top-down” approach to understanding how a pattern of inheritance or trait might be maintained in populations, as well as “bottom-up” modeling of the dynamics of gene expression.     

Teaching Tree-Thinking to Undergraduate Biology Students

Evolution is the unifying principle of all biology, and understanding how evolutionary relationships are represented is critical for a complete understanding of evolution. Phylogenetic trees are the most conventional tool for displaying evolutionary relationships, and “tree-thinking” has been coined as a term to describe the ability to conceptualize evolutionary relationships. Students often lack tree-thinking skills, and developing those skills should be a priority of biology curricula. Many common student misconceptions have been described, and a successful instructor needs a suite of tools for correcting those misconceptions. I review the literature on teaching tree-thinking to undergraduate students and suggest how this material can be presented within an inquiry-based framework.     

Evolutionary ontogenetic aspects of pathogenetics of chronic human diseases

This article is a review of scientific publications, in which issues of pathogenetics of multifactorial diseases (MFDs) are considered from the viewpoint of evolution and ontogeny. Concepts explaining significance of evolutionary processes in the formation of genetic architecture of human chronic diseases (“thrifty” genomes and phenotypes, “drifty genes,” decanalization) are analyzed. The roles of natural selection and genetic drift in the formation of hereditary diversity of genes for susceptibility to MFDs are considered. The modern concept of “disease ontogeny” (somatic mosaicism, loss of heterozygosity, paradominant inheritance, epigenetic variability) is discussed. It is demonstrated that the evolutionary and ontogenetic approaches to analysis of genimuc and other “-omic” data are essential for understanding the biology of diseases.     

Saltational evolution: hopeful monsters are here to stay

Since 150 years it is hypothesized now that evolution always proceeds in a countless number of very small steps (Darwin in On the origin of species by means of natural selection or the preservation of favoured races in the struggle of life, Murray, London, 1859), a view termed “gradualism”. Few contemporary biologists will doubt that gradualism reflects the most frequent mode of evolution, but whether it is the only one remains controversial. It has been suggested that in some cases profound (“saltational”) changes may have occurred within one or a few generations of organisms. Organisms with a profound mutant phenotype that have the potential to establish a new evolutionary lineage have been termed “hopeful monsters”. Recently I have reviewed the concept of hopeful monsters in this journal mainly from a historical perspective, and provided some evidence for their past and present existence. Here I provide a brief update on data and discussions supporting the view that hopeful monsters and saltational evolution are valuable biological concepts. I suggest that far from being mutually exclusive scenarios, both gradual and saltational evolution are required to explain the complexity and diversity of life on earth. In my view, gradual changes represent the usual mode of evolution, but are unlikely to be able to explain all key innovations and changes in body plans. Saltational changes involving hopeful monsters are probably very exceptional events, but since they have the potential to establish profound novelties sometimes facilitating adaptive radiations, they are of quite some importance, even if they would occur in any evolutionary lineage less than once in a million years. From that point of view saltational changes are not more bizarre scenarios of evolutionary change than whole genome duplications, endosymbiosis or impacts of meteorites. In conclusion I argue that the complete dismissal of saltational evolution is a major historical error of evolutionary biology tracing back to Darwin that needs to be rectified.     

The roots of Evo-Devo in Russia: Is there a characteristic “Russian Tradition”?

This paper raises the general question of whether there are any national peculiarities that characterize the scientific and philosophical roots of Russian-language evolutionary developmental biology. The researchers and theories are surveyed which, with hindsight, have been crucial for the Russian tradition when it comes to general methodological principles and constituting concepts. Based on published works and archival documents the main concepts of the “founding fathers” of the Russian tradition with their “Western analogues” are compared. The focus is on A. O. Kowalevsky (1840–1901), I. I. Metschnikov (1945–1916), A. N. Sewertzoff (1866–1936), I. I. Schmalhausen (1884–1963) and the parallelisms between them and E. Haeckel (1834–1919), V. Franz (1883–1950), and C. H. Waddington (1905–1977). In addition, the problem of specific influences constituting the Russian-language context of the Modern Synthesis is addressed. The major thesis of this paper is that the very character of the Russian developmental biology and its intellectual environment predisposed a strong bias towards environmentalist interpretations and thus anticipated what we now call “ecological developmental biology”. This paper is an extended version of my talk delivered to the First and founding meeting of the European Society for Evolutionary Developmental Biology (EDD), 16–19 August (Prague, Czech Republic). I thank Scott Gilbert for inviting me to this meeting

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The evolutionary origins of patriarchy

This article argues that feminist analyses of patriarchy should be expanded to address the evolutionary basis of male motivation to control female sexuality. Evidence from other primates of male sexual coercion and female resistance to it indicates that the sexual conflicts of interest that underlie patriarchy predate the emergence of the human species. Humans, however, exhibit more extensive male dominance and male control of female sexuality than is shown by most other primates. Six hypotheses are proposed to explain how, over the course of human evolution, this unusual degree of gender inequality came about. This approach emphasizes behavioral flexibility, cross-cultural variability in the degree of partriarchy, and possibilities for future change. This work was supported in part by NSF grant BNS-8857969. Barbara Smuts is a professor of psychology and anthropology at the University of Michigan. She received her B.A. in social anthropology at Harvard and her Ph.D. in bio-behavioral sciences at Stanford Medical School. She has studied the behavior of wild chimpanzees, baboons, and bottlenose dolphins and is particularly interested in evolutionary, comparative analyses of female-male relationships.     

Chimera,spandrel, or adaptation

In every known human society, some kind—usually many kinds—of art is practiced, frequently with much vigor and pleasure, so that one could at least hypothesize that “artifying” or “artification” is a characteristic behavior of our species. Yet human ethologists and sociobiologists have been conspicuously unforthcoming about this observably widespread and valued practice, for a number of stated and unstated reasons. The present essay is a position paper that offers an overview and analysis of conceptual issues and problems inherent in viewing art and/or aesthetics as adaptive, and it presents a speculative account of a human behavior of art. Ellen Dissanayake is an independent scholar who has straddled the abyss between biology and art for more than twenty years. She is currently a Visiting Fellow at the Institute for Advanced Studies in the Humanities, University of Edinburgh.     

God’s punishment and public goods

Cooperation towards public goods relies on credible threats of punishment to deter cheats. However, punishing is costly, so it remains unclear who incurred the costs of enforcement in our evolutionary past. Theoretical work suggests that human cooperation may be promoted if people believe in supernatural punishment for moral transgressions. This theory is supported by new work in cognitive psychology and by anecdotal ethnographic evidence, but formal quantitative tests remain to be done. Using data from 186 societies around the globe, I test whether the likelihood of supernatural punishment—indexed by the importance of moralizing “high gods”—is associated with cooperation. Dominic Johnson is a fellow in the Princeton University Society of Fellows. He holds a D.Phil. in biology from Oxford University and a Ph.D. in political science from Geneva University. His research revolves around the evolutionary biology of human behavior and how this impacts on conflict, cooperation, politics, and religion. His recent book, Overconfidence and War: The Havoc and Glory of Positive Illusions, was published in 2004 by Harvard University Press.     

Grandmothers,hunters and human life history

This paper critiques the competing “Grandmother Hypothesis” and “Embodied Capital Theory” as evolutionary explanations of the peculiarities of human life history traits. Instead, I argue that the correct explanation for human life history probably involves elements of both hypotheses: long male developmental periods and lives probably evolved due to group selection for male hunting via increased female fertility, and female long lives due to the differential contribution women’s complex foraging skills made to their children and grandchildren’s nutritional status within groups provisioned by male hunting.     

The random versus fragile breakage models of chromosome evolution: a matter of resolution

Conserved synteny––the sharing of at least one orthologous gene by a pair of chromosomes from two species––can, in the strictest sense, be viewed as sequence conservation between chromosomes of two related species, irrespective of whether coding or non-coding sequence is examined. The recent sequencing of multiple vertebrate genomes indicates that certain chromosomal segments of considerable size are conserved in gene order as well as underlying non-coding sequence across all vertebrates. Some of these segments lost genes or non-coding sequence and/or underwent breakage only in teleost genomes, presumably because evolutionary pressure acting on these regions to remain intact were relaxed after an additional round of whole genome duplication. Random reporter insertions into zebrafish chromosomes combined with computational genome-wide analysis indicate that large chromosomal areas of multiple genes contain long-range regulatory elements, which act on their target genes from several gene distances away. In addition, computational breakpoint analyses suggest that recurrent evolutionary breaks are found in “fragile regions” or “hotspots”, outside of the conserved blocks of synteny. These findings cannot be accommodated by the random breakage model and suggest that this view of genome and chromosomal evolution requires substantial reassessment.