This paper examines David Hull’s and Peter Godfrey-Smith’s accounts of biological individuality using the case of biofilms. Biofilms fail standard criteria for individuality, such as having reproductive bottlenecks and forming parent-offspring lineages. Nevertheless, biofilms are good candidates for individuals. The nature of biofilms shows that Godfrey-Smith’s account of individuality, with its reliance on reproduction, is too restrictive. Hull’s interactor notion of individuality better captures biofilms, and we argue that it offers a better account of biological individuality. However, Hull’s notion of (...) interactor needs more precision. We suggest some ways to make Hull’s notion of interactor and his account of individuality more precise. Generally, we maintain that biofilms are a good test case for theories of individuality, and a careful examination of biofilms furthers our understanding of biological individuality. (shrink)

de Queiroz (1995), Griffiths (1999) and LaPorte (2004) offer a new version of essentialism called "historical essentialism". According to this version of essentialism, relations of common ancestry are essential features of biological taxa. The main type of argument for this essentialism proposed by Griffiths (1999) and LaPorte (2004) is that the dominant school of classification, cladism, defines biological taxa in terms of common ancestry. The goal of this paper is to show that this argument for historical essentialism is unsatisfactory: cladism (...) does not assume that relations of common ancestry are essential attributes of biological taxa. Therefore, historical essentialism is not justified by cladism. (shrink)

Cooperative behaviors within a group face the risk of being exploited by `free-riders,' individuals that reap the benefits produced by cooperators without paying the costs of cooperating. Free-riders are often perceived as a burden to the group, since the group's survival depends on tasks performed by cooperators. However, this paper challenges this perspective, arguing that an excess of cooperators may actually lower the efficiency and persistence of groups. The perspective presented in this paper has ramifications to broader issues in philosophy, (...) particularly the challenge of how to balance self-interest with the collective interests of the group. Ultimately, this paper seeks to highlight some of the subtle ways free-riders positively impact their groups, an aspect of free-riding that is often overlooked in discussions about cooperation. (shrink)

Nature is replete with borderline cases that fall somewhere between organisms and communities, such as lichens, biofilms, and the Portuguese Man-of-War. At first glance, the existence of such borderline cases might suggest that the concept of what constitutes an organism is too fuzzy to be useful in evolutionary biology. Yet, the notion of organisms is entrenched within central debates in evolution, including discussions over how fitness should be measured, what the bearers of adaptations and fitness are, and the status of (...) holobionts. Finally, accounts of organisms can set the stage for explanations of how multicellularity evolved. In particular, characterizing multicellular organisms in terms of the level of cooperation between their cells suggests that their evolution required the presence of mechanisms that could suppress conflict between cells. (shrink)

Kripke argues for origin essentialism, the view that the same individual cannot have multiple origins. Sober hypothesises that Kripke's origin essentialism applies to biological species. This paper shows that Sober's hypothesis fails. Because Kripke's original argument is invalid, it cannot vindicate Sober's proposal. Salmon offers an influential reformulation of Kripke's argument but his argument fails to extend to species: the notion of an individual's origin is too narrow to apply to species, and Salmon's argument rests on a thought experiment that (...) conflicts with how species evolve. Thus, Sober and others are wrong to think that Kripke's origin essentialism can save species essentialism. (shrink)

One curious phenomenon of several social groups is that they are ‘redundant’ in the sense that they contain more cooperators than strictly needed to complete certain group tasks, such as foraging. Redundancy is puzzling because redundant groups are particularly susceptible to invasion by defectors. Yet, redundancy can be found in groups formed by a wide range of organisms, including insects and microbes. Birch ([2012]) has recently argued that coercive behaviours might account for redundancy using insect colonies as a case study. (...) However, microbial examples suggest redundancy can evolve without coercive behaviours. This paper formulates an explanation for redundancy that does not require targeted punishment of defectors; instead, it proposes that redundancy might be due to ignorance. Specifically, it is suggested that redundancy evolves as a by-product of selection when group members have to opt whether to cooperate or not while being blind to the strategies of others. Accordingly, possessing information about the strategies of the group members might undermine rather than facilitate cooperation within groups. (shrink)

Some mathematicians and philosophers contend that set theory plays a foundational role in mathematics. However, the development of category theory during the second half of the twentieth century has encouraged the view that this theory can provide a structuralist alternative to set-theoretical foundations. Against this tendency, criticisms have been made that category theory depends on set-theoretical notions and, because of this, category theory fails to show that set-theoretical foundations are dispensable. The goal of this paper is to show that these (...) criticisms are misguided by arguing that category theory is entirely autonomous from set theory. (shrink)

Microbes often live in association with dense multicellular aggregates, especially biofilms, and the construction of these aggregates typically requires microbial cells to produce public goods, such as enzymes and signaling molecules. Public-goods producers are, in turn, vulnerable to exploitation by free-rider cells that consume the public goods without paying for their production costs. The cell population of a biofilm or other microbial aggregates are expected to pass through bottlenecks due to a wide range of factors, such as antibiotic treatments and (...) dispersal. The goal of this article is to make the case for the relevance of population bottlenecks at shaping the social interactions within microbial aggregates. The effect of bottlenecks on microbial aggregates is complex in that bottlenecks can favor producers under certain circumstances, but not in others. The concept of the Volunteer’s Dilemma from game theory will be used to motivate the hypothesis that this partly occurs because of how bottlenecks alter the risk of being a producer in a microbial aggregate. Finally, the role of bottlenecks in the microbial world impacts key issues in evolutionary biology, including the importance of ecology at shaping social evolution, and the evolution of multicellularity from unicellular ancestors. (shrink)

One curious phenomenon of several social groups is that they are ‘redundant’ in the sense that they contain more cooperators than strictly needed to complete certain group tasks, such as foraging. Redundancy is puzzling because redundant groups are particularly susceptible to invasion by defectors. Yet, redundancy can be found in groups formed by a wide range of organisms, including insects and microbes. Birch has recently argued that coercive behaviours might account for redundancy using insect colonies as a case study. However, (...) microbial examples suggest redundancy can evolve without coercive behaviours. This paper formulates an explanation for redundancy that does not require targeted punishment of defectors; instead, it proposes that redundancy might be due to ignorance. Specifically, it is suggested that redundancy evolves as a by-product of selection when group members have to opt whether to cooperate or not while being blind to the strategies of others. Accordingly, possessing information about the strategies of the group members might undermine rather than facilitate cooperation within groups. 1The Evolution of Redundancy 2Explaining Redundancy via Coercion 3Explaining Redundancy via Ignorance 3.1Cooperation behind the Darwinian veil of ignorance 3.2Modelling group tasks with a public goods game 3.3Group tasks under harsh environments 4Conclusion. (shrink)

Doolittle :351–378, 2013) and Ereshefsky and Pedroso argue that selection can act at the level of biofilms and other microbial communities. Clarke is skeptical and argues that selection acts on microbial cells rather than microbial communities. Her main criticism is that biofilms lack one of the ingredients required for selection to operate: heritability. This paper replies to her concern by elaborating how biofilm-level traits can be inheritable.

Multiple biological groups, such as ant colonies, appear to have a noteworthy inefficiency: they contain vast amounts of redundant members that are not strictly needed to maintain the group. Philosophers and biologists have proposed that such inefficiency is illusory because redundancy enhances the resilience of groups when living under harsh conditions. Still, this proposal is unsatisfactory in different respects. First, it is too vague to account for when redundancy is selectively advantageous. Furthermore, it overlooks cases in which redundancy fails to (...) increase the resilience of groups. This paper offers an account of group redundancy that addresses these difficulties. Specifically, it advances the hypothesis that the mere presence of harsh conditions is not what drives the evolution of redundancy; rather, it is the fact organisms are often unable to predict when they will face harsh conditions. Redundancy enables groups to properly respond to unpredictable circumstances without resorting to the unreliable detection systems of their members. A better understanding of the phenomenon of redundancy is likely to impact other key issues in philosophy of science, including the evolution of cooperation and transitions in individuality, and the role of redundancy in complex systems, be they biological or not. (shrink)