Neither metaphysical dichotomy nor pure identity:: Clarifying the emergentist creed

Emergentism is often misleadingly described as a monolithic “third way” between radical monism and pluralism. In the particular case of biology, for example, emergentism is perceived as a middle course between mechanicism and vitalism. In the present paper I propose to show that the conceptual landscape between monism and pluralism is more complex than this classical picture suggests. On the basis of two successive analyses—distinguishing three forms of tension between monism and pluralism and a distinction between derivational and functional reduction—I define three different versions of emergentism that can be considered as consistent middle courses between monism and pluralism (respectively theoretical, explanatory and causal emergence). I then emphasise the advantage of this taxonomy of the concepts of emergence by applying the results of my analysis to the historical controversy that pertains to the relationship between life and matter.     

Big dragons on small islands: generality and particularity in science

Angela Potochnik’s Idealization and the Aims of Science (Chicago) defends an ambitious and systematic account of scientific knowledge: ultimately science pursues human understanding rather than truth. Potochnik argues that idealization is rampant and unchecked in science. Further, given that idealizations involve departures from truth, this suggests science is not primarily about truth. I explore the relationship between truths about causal patterns and scientific understanding in light of this, and suggest that Potochnik underestimates the importance and power of highly particular narrative explanations.     

The economic approach to ‘theory of mind’

Theory of mind (ToM) is a great evolutionary achievement. It is a special intelligence that can assess not only one''s own desires and beliefs, but also those of others. Whether it is uniquely human or not is controversial, but it is clear that humans are, at least, significantly better at ToM than any other animal. Economists and game theorists have developed sophisticated and powerful models of ToM and we provide a detailed summary of this here. This economic ToM entails a hierarchy of beliefs. I know my preferences, and I have beliefs (a probabilistic distribution) about your preferences, beliefs about your beliefs about my preferences, and so on. We then contrast this economic ToM with the theoretical approaches of neuroscience and with empirical data in general. Although this economic view provides a benchmark and makes useful suggestions about empirical tendencies, it does not always generate a close fit with the data. This provides an opportunity for a synergistic interdisciplinary production of a falsifiable theory of bounded rationality. In particular, a ToM that is founded on evolutionary biology might well be sufficiently structured to have predictive power, while remaining quite general. We sketch two papers that represent preliminary steps in this direction.     

Linking dispersal and marriage in humans: Life history data from Oakham,Massachusetts, USA (1750–1850)

Despite the emphasis on inbreeding avoidance and competition for mates in explaining primate dispersal, little is known about how dispersal and mating interconnect in humans. I examine the link between dispersal and marriage using life history data from Oakham, MA (1750–1850). I find that dispersal status, timing, and destination were linked to marital status, timing, and spouse's place of origin. Men, unmarried individuals, and individuals with spouses from Oakham were less likely to disperse than their counterparts. Individuals with spouses from Oakham also married earlier than others. For women, dispersal and marriage often coincided, and women were more likely to disperse to their spouses' town of origin than were men. Although dispersal coincided with marriage in at least two-thirds of dispersal events, the majority of cases were inconsistent with both inbreeding avoidance and mating competition explanations. Where one of these explanations was still plausible, dispersal seemed more likely linked to competition for mates than to inbreeding, with resource availability also likely shaping dispersal, and male control of resources contributing to sex biases in dispersal.     

RACE,SCIENCE AND A NOVEL: AN INTERDISCIPLINARY DIALOGUE

In the novel Racists by Kunal Basu (2006), two competing scientists initiate an experiment that they believe will prove which race is superior. The research subjects, one white and one black infant, are sequestered on an isolated island in the care of a mute nurse. The contest must be waged in a ‘natural laboratory’ with no artificial interventions and with the prospect that one will die at the hands of the other. The politics of empire, the slave trade and the advent of a new scientific way of viewing life, Darwinism, set the stage for the fictional experiment, but the ramifications of such thinking extend into the present. Coming from the disciplines of nursing, philosophy and science, we discuss how a novel can illuminate the moral dimensions of science and healthcare. The critical distance afforded by the novel provides a rich terrain for the examination of issues such as race, care and the purity of science. Despite the recent dominance of social explanations of race, science requires the examination of the differences between human beings at the biological level. The view that biology is destiny is a powerful one with dangerous consequences, especially since the belief that certain human beings' destinies are far worthier than others is a corollary of such a view. In this paper, we present the cross‐disciplinary conversation, which has been facilitated by this novel. We hope this will inform ethics educators of the rich potential of using fiction as a pedagogical tool.     

Female sand gobies prefer good fathers over dominant males

Female preference for males successful in male-male competition is generally assumed to result in mating with high quality males. Here I report results from an experiment disentangling the effects of intra- and intersexual selection in the sand goby, Pomatoschistus minutus, a marine fish that exhibits paternal care. I show that large males are successful in male–male competition, but contrary to what one would expect, dominants are not preferred by females and are not better at taking care of the eggs. Female preference, however, correlated with the subsequent hatching success of the eggs. Thus, female choice selects for good parenting. Hence, direct benefits in the form of superior paternal care can explain female choice in this species, supporting a good parent process of sexual selection. However, choosing on the outcome of male–male competition does not enable females to mate with the ''best'' males.     

Chemical machines, Maxwell's demon and living organisms

The problem considered in this paper is whether conventional chemical machines can be used in living organisms. I first point out that, due to their molecular nature, living systems pose unique thermodynamic problems, particularly in relation to Maxwell's demon. I then show that these problems may be solved by introducing time into the fundamental statement of the second law so that it becomes valid at the molecular level. This proposal, while clarifying certain logical anomalies in classical thermodynamics, makes no difference to that science in practice. However, I deduce from this statement that there are only two general ways of obtaining useful work from a chemical reaction: the first, a “constrained equilibrium” mechanism, is that employed by conventional chemical engines, but the second, a “molecular energy” mechanism, which depends upon the rapidity of resonant energy-transfer, may not have been suggested before. I then argue that because the former mechanism is essentially macroscopic in character it cannot, in fact, be used in those biological processes, like muscular contraction or active transport, in which useful molecular work is done and that only the latter may be so used. I also suggest reasons why this conclusion has been overlooked. Muscular contraction is used to illustrate these arguments and it is shown that all models of this process so far proposed fall into the first category. Although it is possible to eliminate such models a priori, several examples are finally criticized in detail to clarify the points raised. It is shown that in fact each of these models would have to be a Maxwell's demon machine.     

More than a blog

Blogging is circumventing traditional communication channels and levelling the playing field of science communication. It helps scientists, journalists and interested laypeople to make their voices heard.Last December, astrobiologists reported in the journal Science that they had discovered the first known microorganism on Earth capable of growing and reproducing by using arsenic (Wolfe-Simon et al, 2010). While media coverage went wild, the paper was met with a resounding public silence from the scientific community. That is, until a new breed of critic, science bloggers, weighed in. Leading the pack was Rosie Redfield, who runs a microbiology research lab in the Life Sciences Centre at the University of British Columbia in Vancouver, Canada. She posted a critique of the research to her blog, RRResearch (rrresearch.fieldofscience.com), which went viral. Redfield said that her site, which is typically a quiet window on activities in her lab got 100,000 hits in a week.Redfield said that her site, which is typically a quiet window on activities in her lab got 100,000 hits in a weekThis incident, like a handful before it and probably more to come, has raised the profile of science blogging and the freedom that the Internet offers to express an opinion and reach a broad audience. Yet it also raises questions about the validity of unfettered opinion and personal bias, and the ability to publish online with little editorial oversight and few checks and balances.Redfield certainly did not hold back in her criticism of the paper. Her post said of the arsenic study: “Lots of flim-flam, but very little reliable information. [...] If this data was presented by a PhD student at their committee meeting, I''d send them back to the bench to do more clean-up and controls.” She also opined on why the article was published: “I don''t know whether the authors are just bad scientists or whether they''re unscrupulously pushing NASA''s ''There''s life in outer space!'' agenda. I hesitate to blame the reviewers, as their objections are likely to have been overruled by Science''s editors in their eagerness to score such a high-impact publication.”Despite the fervor and immediacy of the blogosphere, it took Science and Felisa Wolfe-Simon, the lead author on the paper, nearly six months to respond in print. Eventually, eight letters appeared in Science covering various aspects of the controversy, including one from Redfield, who is now studying the bacteria in her lab. Bruce Alberts, editor-in-chief of Science, downplayed the role that blogging played in drumming up interest in the controversial study. “I am sure that the number of letters sent to us via our website reflected a response to the great publicity the article received, some of it misleading [...] This number was also likely expanded by the blogging activity, but it was not directly connected to the blogs in any way that I can detect,” he explained.Bloggers, of course, have a different take on the matter, arguing that it was another example of a growing number of cases of ''refutation by blog''. The blogging community heralds Redfield as a hero to science and science blogging. By now, more traditional science media outlets have also joined the bloggers in their skepticism over the paper''s claims, with many repeating the points Redfield made in her original blog response.Jerry Coyne, an evolutionary geneticist at the University of Chicago in the USA, writes the blog Why Evolution is True (whyevolutionistrue.wordpress.com), which is a spinoff from his book of the same name. He said that bloggers, both professional scientists and journalists, have been gaining a new legitimacy in recent years as a result of things such as the arsenic bacteria case, as well as from shooting holes in the 2009 claims that the fossil of the extinct primate Darwinius masillae from the Messel Pit in Germany was a ''missing link'' between two primate species (Franzen et al, 2009). “[Blogging has] really affected the pace of how science is done. One of the good things about science blogging, certainly as a professional, is you''re able to pass judgment on papers instantly. You don''t have to write a letter to the editor and have it reviewed. [Redfield] is a good example of the value of science blogging. Claims that are sort of outlandish and strong can be discredited or at least addressed instantaneously instead of waiting weeks and weeks like you''d otherwise have to do,” he said.“... you''re able to pass judgment on papers instantly. You don''t have to write a letter to the editor and have it reviewed”Perhaps because of the increasingly public profile of popular science bloggers, as well as the professional and social value that is becoming attached to their blogs, science blogging is gaining in both popularity and validity. The content in science blogs covers a wide spectrum from genuine science news to simply describing training or running a lab, to opinionated rants about science and its social impact. The authorship is no less diverse than the content with science professionals, science journalists and enthusiastic amateurs all contributing to the melting pot, which also has an impact on the quality.Carl Zimmer is a freelance science journalist, who writes primarily for the New York Times and Discover Magazine, and blogs at The Loom (blogs.discovermagazine.com/loom). “Most scientists have not been trained how to write, so they are working at a disadvantage,” he said. “[Writing for them] would be like me trying to find a dinosaur. I wouldn''t do a very good job because I don''t really know how to do that. There are certainly some scientists who have a real knack for writing and blogs have been a fantastic opportunity for them because they can just start typing away and all of a sudden have thousands of people who want to read what they write every day.”Bora Zivkovic, who is a former online community manager at Public Library of Science, focusing mainly on PLoS ONE, is one of those scientists. A native of Belgrade, he started commenting in the mid-1990s about the Balkan wars on Usenet, an Internet discussion network. He began blogging about science and politics in 2004 and later about his interest in chronobiology, which stems from his degree in the topic from North Carolina State University. He still combines these interests in his latest blog, Blog Around the Clock (blogs.scientificamerican.com/a-blog-around-the-clock). Last year, Scientific American named Zivkovic its blog editor and he set up a blogging network for the publication. “There isn''t really a definition of what is appropriate,” he said. “The number one rule in the blogosphere is you never tell a blogger what to blog about. Those bloggers who started on their own who are scientists treasure their independence more than anything, so networks that give completely free reign and no editorial control are the only ones that can attract interesting bloggers with their own voices.”“The number one rule in the blogosphere is you never tell a blogger what to blog about”Daniel McArthur, an Australian scientist now based in the UK, who blogs about the genetic and evolutionary basis of human variation at Genetic Future (www.wired.com/wiredscience/geneticfuture), and about personal genomics at Genomes Unzipped (www.genomesunzipped.org), said that it is difficult to define a science blog. “I think it''s semantics. There are people like me who spend some time writing about science and some time writing about industry and gossiping about things in the industrial world. Then there are the people who write about the process of doing science. There are many, many blogs where [...] the content is much more about [the blogger''s] personal voyage as a scientist rather than the science that they do. Then there are people who use science blogging as an extra thing that they do and the primary purpose of their blog is to add political advocacy. I think it''s very hard to draw a line between the different categories. My feeling is that science bloggers should write about whatever it is they want to write about .”The ability to distribute your opinion, scientific or otherwise, online and in public is raising difficult questions about standards and the difference between journalism and opinion. Sean Carroll, who writes for the physics group blog Cosmic Variance (blogs.discovermagazine.com/cosmicvariance), is a senior research associate in the Department of Physics at the California Institute of Technology in the USA. “Some blogging is indistinguishable from what you would ordinarily call journalism. Some blogging is very easily distinguishable from what you would ordinarily call journalism,” he said. “I think that whether we like it or not, the effect of the Internet is that readers need to be a little bit more aware of the status of what they are looking at. Is this something reputable? Anyone can have a blog and say anything, so that one fact is both good and bad. It''s bad because there is a tremendous amount of rubbish on the Internet [...] and people who have trouble telling the rubbish from the good stuff will get confused. But it''s also good because it used to be the case that only a very small number of voices were represented in major media.”Zimmer contrasts the independence of blogging with traditional journalism. “You really get to set your own rules. You''re not working with any editor and you''re not trying to satisfy them. You''re just trying to satisfy yourself. In terms of the style of what I do, I will tend to write more—I think of [my blog posts] as short essays, as opposed to an article in the New York Times where I''ll be writing about interviewing someone or describing them on a visit I paid to them. One of the great things about a blog is that it''s a way of making a connection with people who are your readers and people who are following you for a long time.”One of the world''s most popular scientist bloggers is Paul Zachary Myers, known as PZ, a biology professor at the University of Minnesota in the USA. He blogs at Pharyngula (scienceblogs.com/pharyngula), a site named for a particular stage in development shared by all vertebrate embryos. “Passion is an important part of this. If you can communicate a love of the science that you''re talking about, then you''re a natural for blogging,” he explained. “[Pharyngula] is a blog where I have chosen just to express myself, so self-expression is the goal and what I write about are things that annoy me or interest me.”“Passion is an important part of this. If you can communicate a love of the science that you''re talking about, then you''re a natural for blogging”Myers'' blog, which is driven by a mix of opinion, colourful science writing, campaigning against creationism and an unflinching approach to topics about which he is passionate, draws about 3 million visitors a month. He said his blog attracts more traffic than other blogs because it is not purely about science. “I do a lot of very diverse things such as controversial religious stuff and politics, and whatever I feel like. So I tap into a lot of interest groups and that builds up my rank quite a bit. I''d say there are quite a few other science blogs out there that are pure science blogs, but pure science blogs—where they just talk about science and nothing but science—cannot get quite as much traffic as a more broadly based blog.”In an example of his sometimes-incendiary posting, Myers recently took on the Journal of Cosmology regarding an article on the discovery of bacteria fossils in a meteorite. He said that the counterattack got personal, but that he usually enjoys “the push back” from readers. “That''s part of the argument. I would say that everyone has an equal right to make their case on the web. That''s sometimes daunting for some people, but I think it''s part of the give and take of free speech. It''s good. It''s actually kind of fun to get into these arguments.”Beyond the circus that can surround blogs such as Pharyngula, scientist bloggers are debating whether their blogging counts as a professional activity. Redfield said that blogging can be taken into account among the outreach some governments now require from researchers who receive public funds. She said that some researchers now list their blogging activity in their efforts to communicate science to the public.Coyne, however, does not share his interest in blogging with other senior faculty at the University of Chicago, because he does not believe they value it as a professional activity. Still, he said that he recognizes the names of famous scientists among his blog readers and argues that scientists should consider blogging to hone their writing skills. “Blogging gives you outreach potential that you really should have if you''re grant funded, and it''s fun. It opens doors for you that wouldn''t have opened if you just were in your laboratory. So I would recommend it. It takes a certain amount of guts to put yourself out there like that, but I find it immensely rewarding,” he said. In fact, Coyne has had lecture and print publishing opportunities arise from his blogs.“It opens doors for you that wouldn''t have opened if you just were in your laboratory [...] It takes a certain amount of guts to put yourself out there like that...”Redfield said she finds blogging—even if no one reads her posts—a valuable way to focus her thoughts. “Writing online is valuable at all levels for people who choose to do it. Certainly, by far the best science writing happening is in the community of writers who are considered bloggers,” she said.In terms of pay, science blogging usually remains in the ''hobby zone'', with pay varying widely from nothing at all to small amounts from advertising and web traffic. ''GrrlScientist'', an American-trained molecular evolutionary biologist based in Germany, who prefers to go by her nom de blog, has been blogging for seven years. She writes the popular Punctuated Equilibrium blog (www.guardian.co.uk/science/punctuated-equilibrium) for The Guardian newspaper in the UK, as well as Maniraptora (blogs.nature.com/grrlscientist) for the Nature Network, and is co-author of This Scientific Life (scientopia.org/blogs/thisscientificlife) for the science writing community Scientopia. She said she earns a small amount from ad impressions downloaded when her blog is viewed at The Guardian. On the other end of the scale is Myers, who declined to disclose his income from blogging. “It''s a respectable amount. It''s a nice supplement to my income, but I''m not quitting my day job,” he said.Yet bloggers tend not to do it for the money. “I know that when I go to give talks, the fact that I have the blog is one of the first things that people mention, and lots of students in particular say that they really enjoy the blog and that they''re encouraged by it,” Carroll explained. “Part of what we do is not only talk about science, but we act as examples of what it means to be scientist. We are human beings. We care about the world. We have outside interests. We like our jobs. We try to be positive role models for people who are deciding whether or not this is something that they might want to get into themselves one day.”The rise of the science blogosphere has not all been plain sailing. Although the Internet has been hailed as a brave new world of writing where bloggers can express themselves without interference from editors or commercial interests, it has still seen its share of controversy. The blogging portal ScienceBlogs was the launchpad for some of the best and most popular writers of the new generation of science bloggers, including Myers and Zivkovic. But an incident at ScienceBlogs shook up the paradise and raised journalistic ethical quandaries.In July 2010, a new site, Food Frontiers (foodfrontiers.pepsicoblogs.com), appeared on ScienceBlog, sponsored by PepsiCo, the makers of the popular drink. The blog featured posts written by the beverage maker''s representatives and was blended in with the other blog content on the portal. “Pepsi''s blog looked like my blog or PZ''s blog,” Zivkovic explained, “with no warning that this was paid for and written by Pepsi''s R&D or PR people [...] talking about nutrition from a Pepsi perspective, which is a breach in the wall between advertorial and editorial. The moment the Pepsi blog went live, about 10 bloggers immediately left.” He said that the journalist-bloggers in particular pointed to a break of trust that would sully the reputation of ScienceBlogs writers and confuse readers.In his final blog at the site, titled ''A Farewell to Scienceblogs: the Changing Science Blogging Ecosystem'', Zivkovic nailed the danger of the ''Pepsigate'' incident to the validity of the blogosphere. He wrote: “What is relevant is that this event severely undermined the reputation of all of us. Who can trust anything we say in the future? Even if you already know me and trust me, can people arriving here by random searches trust me? Once they look around the site and see that Pepsi has a blog here, why would they believe I am not exactly the same, some kind of shill for some kind of industry?” (scienceblogs.com/clock/2010/07/scienceblogs_and_me_and_the_ch.php). Myers, who at the time was responsible for more than 40% of the traffic at ScienceBlogs, went ''on strike'' to protest. In the aftermath, the Pepsi blog was pulled.Redfield raises another interesting word of caution. “Most scientists are extensively worried about being scooped, so they''re scared to say anything about what''s actually going on in their lab for fear that one of their competitors will steal their ideas,” she said. In this context, social networking sites such as ResearchGate (www.researchgate.net; Sidebar A) might be a more appropriate avenue for securely sharing ideas and exchanging tips and information because it enables users to control who has access to their missives.“... they''re scared to say anything about what''s actually going on in their lab for fear that one of their competitors will steal their ideas”

Sidebar A | ResearchGate—social media goes pro

Whenever she is looking for ideas for a research project, biologist Anne-Laure Prunier, who works in the Department of Cellular Biology and Infection at the Institut Pasteur in Paris, has recently turned to ResearchGate (www.researchgate.net), the scientists'' version of the social networking site Facebook. “Every time I have used ResearchGate, I found it really useful,” she commented.ResearchGate, based in Berlin, Germany and Cambridge, USA, is a free service that launched in January 2009. It was co-founded by Ijad Madisch, who earned his MD and PhD from the University of Hannover''s medical school in Germany and is a former research fellow at Harvard Medical School. He explained that his goal in starting the network was to make research more efficient. “During my research in Boston, I noticed that science is very inefficient, especially if you''re doing an experiment and trying to get feedback from people working on the same problem. You don''t have any platforms, online networks where you can go and ask questions or if you''re trying to find someone with a specific skill set. So I decided to do that on my own.”As a result, the site offers researchers functionality similar to Facebook—the modern template for social networking. Through ResearchGate, members can follow colleagues, be followed by those interested in their research, share their conference attendance and recent papers—their own or those that interest them—and most importantly, perhaps, ask and answer questions about science and scientific techniques.“You can get in touch with a lot of different people with a lot of different backgrounds,” Prunier explained. “When I have a very precise technical question for which I don''t find an answer in my institute, I turn to ResearchGate and I ask this question to the community. I have done it three times and every time I have gotten a lot of answers and comments, and I was able to exchange information with a lot of different people which I found really useful.”By May 2011, ResearchGate had reached one million members across 192 countries. The largest numbers of registrations come from the USA, the UK, Germany and India. Biologists, who are second only to medical doctors on the site, make up more than 20% of members. In addition to blogging, ResearchGate is just one example of how the Internet—originally invented to allow physicists to share data with one another—is changing the way that scientists communicate and share information with each other and the public.Carroll, on the other hand, who has been blogging since 2004, said that physicists are very comfortable about publicly sharing research papers with colleagues online. “The whole discussion gets very heated and very deep in some places about open access publishing. Physicists look on uncomprehendingly in fact because they put everything for free on line. That''s what we''ve been doing for years. It works.” But he said they are more cautious about blogging for a general audience. By contrast, he believes biology is especially well-suited to being blogged. “[Biologists are] actually more comfortable with talking to a wider audience because biology, whether it is through medicine or through debates about creationism or life on other planets or whatever, gets involved with public debate quite often.”Zivkovic agrees: “PZ [Myers] and me and a number of others are interested in reaching a broad lay audience, showing how science is fun and cool and interesting and important in various ways. Connecting science to other areas of life, from art to politics and showing the lay audience how relevant science is to everyday life”. Even so, he pointed out that although blogging is popularizing science with the public, there is a less-mainstream sphere serving professional scientists as a forum for surviving the cut and thrust of modern science. “There is a strong subset of the science blogosphere that discusses a life in science, career choices, how to succeed in academia [...] A lot of these are written by people who [...] believe that if their real names were out there it could jeopardize their jobs. They''re not interested in talking to lay audiences. They are discussing survival techniques in today''s science with each other and providing a forum for other young people coming into science.”Ultimately, whether you read popular science blogs, trawl deeper for survival tips, or write your own, the science blogosphere is expanding rapidly and is likely to do so for years to come.     

Mixed interactions among life history stages of two harvested related species

Climate change and harvesting can affect the ecosystems'' functioning by altering the population dynamics and interactions among species. Knowing how species interact is essential for better understanding potentially unintended consequences of harvest on multiple species in ecosystems. I analyzed how stage‐specific interactions between two harvested competitors, the haddock (Melanogrammus aeglefinus) and Atlantic cod (Gadus morhua), living in the Barents Sea affect the outcome of changes in the harvest of the two species. Using state‐space models that account for observation errors and stochasticity in the population dynamics, I run different harvesting scenarios and track population‐level responses of both species. The increasing temperature elevated the number of larvae of haddock but did not significantly influence the older age‐classes. The nature of the interactions between both species shifted from predator‐prey to competition around age‐2 to ‐3. Increased cod fishing mortality, which led to decreasing abundance of cod, was associated with an increasing overall abundance of haddock, which suggests compensatory dynamics of both species. From a stage‐specific approach, I show that a change in the abundance in one species may propagate to other species, threatening the exploited species'' recovery. Thus, this study demonstrates that considering interactions among life history stages of harvested species is essential to enhance species'' co‐existence in harvested ecosystems. The approach developed in this study steps forward the analyses of effects of harvest and climate in multi‐species systems by considering the comprehension of complex ecological processes to facilitate the sustainable use of natural resources.     

Intraspecific competition reduces niche width in experimental populations

Intraspecific competition is believed to drive niche expansion, because otherwise suboptimal resources can provide a refuge from competition for preferred resources. Competitive niche expansion is well supported by empirical observations, experiments, and theory, and is often invoked to explain phenotypic diversification within populations, some forms of speciation, and adaptive radiation. However, some foraging models predict the opposite outcome, and it therefore remains unclear whether competition will promote or inhibit niche expansion. We conducted experiments to test whether competition changes the fitness landscape to favor niche expansion, and if competition indeed drives niche expansion as expected. Using Tribolium castaneum flour beetles fed either wheat (their ancestral resource), corn (a novel resource) or mixtures of both resources, we show that fitness is maximized on a mixed diet. Next, we show that at higher population density, the optimal diet shifts toward greater use of corn, favoring niche expansion. In stark contrast, when beetles were given a choice of resources, we found that competition caused niche contraction onto the ancestral resource. This presents a puzzling mismatch between how competition alters the fitness landscape, versus competition's effects on resource use. We discuss several explanations for this mismatch, highlighting potential reasons why optimality models might be misleading.     

The tribunal of philosophy and its norms: history and philosophy in Georges Canguilhem’s historical epistemology

In this article I assess Georges Canguilhem’s historical epistemology with both theoretical and historical questions in mind. From a theoretical point of view, I am concerned with the relation between history and philosophy, and in particular with the philosophical assumptions and external norms that are involved in history writing. Moreover, I am concerned with the role that history can play in the understanding and evaluation of philosophical concepts. From a historical point of view, I regard historical epistemology, as developed by Gaston Bachelard and Georges Canguilhem, as a conception and practice which came out of the project, elaborated in France from the 1920s to the 1940s, of combining history of science and philosophy. I analyse in particular Canguilhem’s epistemology in his theory and practice of history of science. What he called ‘normative history’ is the focus of my analysis. I evaluate the question of the nature and provenience of the norm employed in normative history, and I compare it with the norm as discussed by Canguilhem in Le normal et le pathologique. While I am critical of Canguilhem’s treatment of history, I conclude that his philosophical suggestion to analyse the formation of scientific concepts ‘from below’ represents a useful model for history and philosophy of science, and that it can be very profitably extended to philosophical concepts.     

Tree-grass co-existence in savanna: Interactions of rain and fire

The mechanisms permitting the co-existence of tree and grass in savannas have been a source of contention for many years. The two main classes of explanations involve either competition for resources, or differential sensitivity to disturbances. Published models focus principally on one or the other of these mechanisms. Here we introduce a simple ecohydrologic model of savanna vegetation involving both competition for water, and differential sensitivity of trees and grasses to fire disturbances. We show how the co-existence of trees and grasses in savannas can be simultaneously controlled by rainfall and fire, and how the relative importance of the two factors distinguishes between dry and moist savannas. The stability map allows to predict the changes in vegetation structure along gradients of rainfall and fire disturbances realistically, and to clarify the distinction between climate- and disturbance-dependent ecosystems.     

Paradoxical suppression of poly-specific broadly neutralizing antibodies in the presence of strain-specific neutralizing antibodies following HIV infection

One of the first immunologic responses against HIV infection is the presence of neutralizing antibodies that seem able to inactivate several HIV strains. Moreover, in vitro studies have shown the existence of monoclonal antibodies that exhibit broad crossclade neutralizing potential. Yet their number is low and slow to develop in vivo. In this paper, we investigate the potential benefits of inducing poly-specific neutralizing antibodies in vivo throughout immunization. We develop a mathematical model that considers the activation of families of B lymphocytes producing poly-specific and strain-specific antibodies and use it to demonstrate that, even if such families are successful in producing neutralizing antibodies, the competition between them may limit the poly-specific response allowing the virus to escape. We modify this model to account for viral evolution under the pressure of antibody responses in natural HIV infection. The model can reproduce viral escape under certain conditions of B lymphocyte competition. Using these models we provide explanations for the observed antibody failure in controlling natural infection and predict quantitative measures that need to be satisfied for long-term control of HIV infection.     

Conjecture and explanation: A reply to Reydon

Reydon (2012) comments on my account of how-possibly explanation (Forber, 2010). I distinguish between three types of explanation (global how-possibly, local how-possibly, and how actually) and argue that these distinctions track various roles explanations play in evolutionary biology. While Reydon accepts the distinctions, he questions whether the two different types of how-possibly explanation count as genuine explanations. He summarizes his analysis with a slogan: “global how-possibly explanations are explanations but not how-possibly; local explanations are how-possibly but not explanations.” Reydon’s commentary raises a number of insightful points, and I will not be able to address them all. Instead, after clarifying certain points in my original paper (4 1), I will respond to Reydon’s slogan by addressing whether global how-possibly explanations should count as explaining how possible (4 2), and what (so-called) local how-possibly explanations are, if not explanations (4 3).     

Waddington redux: models and explanation in stem cell and systems biology

Stem cell biology and systems biology are two prominent new approaches to studying cell development. In stem cell biology, the predominant method is experimental manipulation of concrete cells and tissues. Systems biology, in contrast, emphasizes mathematical modeling of cellular systems. For scientists and philosophers interested in development, an important question arises: how should the two approaches relate? This essay proposes an answer, using the model of Waddington’s landscape to triangulate between stem cell and systems approaches. This simple abstract model represents development as an undulating surface of hills and valleys. Originally constructed by C. H. Waddington to visually explicate an integrated theory of genetics, development and evolution, the landscape model can play an updated unificatory role. I examine this model’s structure, representational assumptions, and uses in all three contexts, and argue that explanations of cell development require both mathematical models and concrete experiments. On this view, the two approaches are interdependent, with mathematical models playing a crucial but circumscribed role in explanations of cell development.     

Butterflies tailor their ejaculate in response to sperm competition risk and intensity

Males of many insects eclose with their entire lifetime sperm supply and have to allocate their ejaculates at mating prudently. In polyandrous species, ejaculates of rival males overlap, creating sperm competition. Recent models suggest that males should increase their ejaculate expenditure when experiencing a high risk of sperm competition. Ejaculate expenditure is also predicted to vary in relation to sperm competition intensity. During high intensity, where several ejaculates compete for fertilization of the female''s eggs, ejaculate expenditure is expected to be reduced. This is because there are diminishing returns of providing more sperm. Additionally, sperm numbers will depend on males'' ability to assess female mating status. We investigate ejaculate allocation in the polyandrous small white butterfly Pieris rapae (Lepidoptera). Males have previously been found to ejaculate more sperm on their second mating when experiencing increased risk of sperm competition. Here we show that males also adjust the number of sperm ejaculated in relation to direct sperm competition. Mated males provide more sperm to females previously mated with mated males (i.e. when competing with many sperm) than to females previously mated to virgin males (competing with few sperm). Virgin males, on the other hand, do not adjust their ejaculate in relation to female mating history, but provide heavier females with more sperm. Although virgin males induce longer non-receptive periods in females than mated males, heavier females remate sooner. Virgin males may be responding to the higher risk of sperm competition by providing more sperm to heavier females. It is clear from this study that males are sensitive to factors affecting sperm competition risk, tailoring their ejaculates as predicted by recent theoretical models.     

THE COMPONENTS OF KIN COMPETITION

It is well known that competition among kin alters the rate and often the direction of evolution in subdivided populations. Yet much remains unclear about the ecological and demographic causes of kin competition, or what role life cycle plays in promoting or ameliorating its effects. Using the multilevel Price equation, I derive a general equation for evolution in structured populations under an arbitrary intensity of kin competition. This equation partitions the effects of selection and demography, and recovers numerous previous models as special cases. I quantify the degree of kin competition, α, which explicitly depends on life cycle. I show how life cycle and demographic assumptions can be incorporated into kin selection models via α, revealing life cycles that are more or less permissive of altruism. As an example, I give closed‐form results for Hamilton's rule in a three‐stage life cycle. Although results are sensitive to life cycle in general, I identify three demographic conditions that give life cycle invariant results. Under the infinite island model, α is a function of the scale of density regulation and dispersal rate, effectively disentangling these two phenomena. Population viscosity per se does not impede kin selection.     

Evolution of Pair-Living in <Emphasis Type="Italic">Phaner furcifer</Emphasis>

Pair-living evolved several times independently in the primate lineage and most likely for more than one reason. Currently, there are 7 hypotheses regarding the evolution of pair-living in primates. They may explain several but not all cases. I investigated the applicability of the explanations to fork-marked lemurs Phaner furcifer. I used information from a long-term study on 8 fork-marked lemur families in Kirindy Forest to evaluate the hypotheses. Fork-marked lemurs live in uniform dispersed pairs, which share and defend a territory but spend three-quarters of their activity time apart from each other. Unconditional female dominance and lack of permanent close association between pair-partners disqualify most hypotheses. Lack of male parental care and long travel distances in small home ranges disqualify other explanations. I conclude that there is no support a priori for any current pair-living hypothesis and that the newly formulated intersexual-feeding-competition hypothesis best explains the evolution of pair-living in fork-marked lemurs. Accordingly, female range exclusivity evolved first as a consequence of intense feeding competition. Subsequently, indirect feeding competition drove females to accept a single male to share their territory as a defense against feeding competition from males whose ranges unsystematically overlap those of several females. This situation led to pair-living because formation of dispersed one-male-multifemale-units was too costly for males in terms of reduced foraging efficiency.     

Generating and testing predictions about community structure: Which theory is relevant and can it be tested with observational data?

Three issues are discussed relevant to the controversy over using null models and observational data on guild structure to test community-level predictions based on limiting similarity theory. First, I argue that most limiting similarity theory is not based on reasonable assumptions for plants and that the theory that is relevant does not generate any predictions about expected guild proportionality on a small spatial scale. Therefore, regardless of adequacy of the statistical methods, the predictions being tested by the body of literature using null models to test for niche limitation are unlikely to be relevant in most plant comunities. Second, assuming that the predictions are after all worth being tested, I argue that most tests using the guild approach do not provide adequate explanations of how the defined guilds could lead to greater competition within vs. between guilds. If this is not true for the particular guilds used, the predictions of guild proportionality or size constancy will not be valid. Third, I address the controversy over whether field experiments can provide more solid evidence than observational data about the role of competition in determining community structure by (1) suggesting methods of dealing with potential drawbacks of field experiments, and (2) suggesting alternative experimental approaches for directly addressing issues about community structure.