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Archive for the ‘Philosophy of Biology’ Category

Giuliana Pulvirenti: Review of Farine R. D. “Social network analysis of mixed-species flocks: exploring the structure and evolution of interspecific social behavior”.

In Philosophy of Biology, Pulvirenti, Review on March 29, 2013 at 1:20 PM

Functional explanations advocated for mixed-species groups (mainly foraging and anti-predator advantages) are based on top-down approaches that implicitly assume the species as fixed and static social structures and shift the analysis of fitness benefits and costs from the level of individuals to the one of the groups/species. According to Farine, this operation of over-simplification leads to cursory inferences. On the contrary, a bottom-up approach, usually used to study intraspecific sociality, could provide an insight and a better understanding of the emergent and dynamic properties at each level of the social system. In this perspective, the author proposes Social Network Analysis (SNA) as a tool to measure inter-individual interaction within mixed species flocks. His aim is to explore the different roles within the flocks and the individual variations of sociality, as well as the fitness consequences that such variations leads to both individual and community structure. SNA main strength is the possibility to graphically represent and quantify, at any scale between dyads and groups, specific aspects of social relationships, such as number, intensity, frequency of direct and indirect interactions and individual roles, centrality (i.e. “keystone” individuals). As an istance, Loussou & Newman (2004) found a “keystone” individual in a bottlenose dolphin community in Scotland that acted as a bridge between two subgroups, therefore playing a critical role in keeping the connection between them. However, SNA current applications raise some issues concerning spatial and temporal constraints (Wey et al. 2008). On one hand, pattern of associations vary on a case by case basis depending on habitat topology and distribution of resources, while on the other hand, it’s important to distinguish genuine social network structures from relationships explained solely by shared space use. Furthermore, traditional graph models are limited in addressing temporal questions regarding changes that may occur over a given time period. Future work must also go beyond simple description, beginning to link network structure to biological and evolutionary consequences, in order to answer the “why” questions in sociobiological and ethological studies (Hock & Fefferman 2011).

Bibliography

Farine Damien R., Garroway Colin J., Sheldon Ben C. (2012), Social network analysis of mixed-species flocks: exploring the structure and evolution of interspecific social behavior, in Animal Behaviour 84: 1271-1277.

Hock C. & Fefferman N. (2011), Extending the role of social networks to study social organization and interation structure of animal groups, in Ann. Zool. Fennici 48: 365-370.  http://www.bioone.org/doi/abs/10.5735/086.048.0604

Lusseau D. & Newman M. E. J. (2004), Identifying the role that animals play in their social networks, in Proceedings of the Royal Society B (suppl): Biological Sciences 271: 477- 481. http://rspb.royalsocietypublishing.org/content/271/Suppl_6/S477.short

Sih A., Hanser S. F. & McHugh K. A. (2009), Social network theory: new insights and issues for behavioral ecologists, in Behav. Ecol. Sociobiol. 63: 975-988. http://link.springer.com/article/10.1007%2Fs00265-009-0725-6?LI=true

Sueur C., Jacobs A., Amblard F., Petit O., King A. J. (2011), How can social network analysis improve the study of primate behavior?, in American Journal of Primatology 73: 703-719. http://onlinelibrary.wiley.com/doi/10.1002/ajp.20915/abstract

Wey T., Blumstein D. T., Shen W. & Jordan F. (2008), Social network analysis of animal behaviour: a promising tool for the study of sociality, in Animal Behaviour 75: 333-344. http://www.colbud.hu/apc-aa/img_upload/4d11dfd490c468ca39fcefabae592944/JordanAniBe2008.pdf

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Herbert Spencer and Organism-Environment Interaction

In Morganti, Philosophy of Biology on March 28, 2013 at 8:54 AM

In a recently published paper Trevor Pearce (2010) has provided an interesting account of the steps which conducted Herbert Spencer (1820-1903) to adopt the term ‘environment’ as opposed to the plural noun ‘circumstances’. According to Pearce, this shift took place as Spencer moved to a conception of both organism and environment as opposite and distinct entities. Undoubtedly, Pearce’s article has the historiographical merit of identifying some important contributions to the development of Spencer’s biological thought (such as Lamarck 1809; Chambers 1844; Comte via Martineau 1845). Nevertheless, the hypothesis that Spencer held a conception of the organism-environment interaction as that indicated by Pearce is fairly arguable. In the first place, though Spencer came to adopt the singular noun ‘environment’ (which he had found in Martineau 1845), he conceived the environment itself not as a monolithic block, but rather as a plurality of physical forces. Secondly, and most notably, he believed that those very forces were constantly redefined by organisms themselves according to their level of heterogeneity and complexity (Spencer 1864-67, I, 418, 421-23; 1870-72, I, 193-227). Thus, it is difficult to credit Spencer with a view of organism and environment as polarly opposed entities. On the whole, it is not easy to place Spencer in the history of the concept of environment. In fact, while his advocacy of the idea of a reciprocal construction of organisms and environments seems close to modern thinking, still he is quite distant from it in his constant attempt to reduce biological and ecological notions to the language of physics.

Federico Morganti

Bibliography

 

Lamarck, J.-B. (1809), Philosophie zoologique, ou exposition des considérations relatives à l’histoire naturelle des animaux (2 vols.), Dentu: Paris.

Chambers, R. (1844), Vestiges of the Natural History of Creation, J. Churchill: London.

Martineau, H. (1845), The Positive Philosophy of August Comte (2 vols.), J. Chapman: London.

Pearce, T. (2010). From ‘circumstances’ to ‘environment’: Herbert Spencer and the origins of the idea of organism-environment interaction. Studies in History and Philosophy of Biological and Biomedical Sciences 41: 241-52.

Spencer, H. (1864-67), The Principles of Biology (2 vols.), Williams and Norgate: London.

Spencer, H. (1870-72), The Principles of Psychology, 2nd ed. (2 vols.), Williams and Norgate: London.

Ivan D’Annibale: Review of Marshall, R.A.J., “Group selection and kin selection: formally equivalent approaches.”

In D'Annibale, Philosophy of Biology, Review on March 28, 2013 at 8:47 AM

The level at which natural selection “acts” has been a much debated issue in evolutionary biology (Okasha 2006), especially in connection with the evolution of altruism. Two major kinds of explanations have been proposed: group selection theory (GST) and inclusive fitness theory (IFT). Marshall (2011) surveys the most common objections to the latter, claiming that the two approaches are in fact formally equivalent. We discuss exclusively his claim of equivalence. Rewriting of the Price equation (Price 1970) yields: 1) a version of Hamilton’s rule (a basic tool in IFT); 2) a partition of selection in between-group and within-group selection (typical of GST explanations). Thus, 1) and 2) are formally equivalent. If we assume that 1) holds, then also 2) holds, and conversely. Is this the same as saying that IFT and GST are formally equivalent? The author concedes that IFT cannot be identified with Hamilton’s rule. Thus the claim of formal equivalence must be, at least as far as this article goes, re-evaluated. On the other hand, to prove formal equivalence it requires an explicit set of axioms to be given. This request seems honestly unreasonable. Even in the case where such a formal model could be described, it remains dubious that many, or any, would agree on it. The word “theory”, as in “inclusive fitness theory” and “group selection theory”, should be better understood as a set of different but related explanations (for IFT alone, in addition to Hamilton’s rule and the Price equation, population genetics and evolutionary game theory have been useful approaches, among others). In particular, formal models are currently being used with a more modest goal: to describe more limited and well defined (agreed upon) aspects of the world, in order to produce testable predictions. On a final note, even if any two of these models will be found to be formally equivalent, we may have gained a more thorough “understanding” in the process. Mathematics also, after all, is more than the axioms that we put into it.

Bibliography

Okasha, S. (2006), Evolution and the Levels of Selection, Oxford: Oxford University Press.

Marshall, J.A.R. (2011), Group selection and kin selection: formally equivalent approaches, Trends in Ecology and Evolution, 26 (7): 325-332.

Price, G.R. (1970), Selection and covariance, Nature, 227 (5257): 520-521.
(I thank all the participants in our last reading group for discussing and sharing ideas).

Are Evolutionary Debunking Arguments really self-defeating?

In Philosophy of Biology, Sterpetti on March 25, 2013 at 4:07 PM

Recently Helen De Cruz and her co-authors supported the view that Evolutionary Debunking Arguments (EDAs) (Kahane 2011) are self-defeating. Their argument can be summarized as follows: if human knowledge is not reliable since human reasoning is not truth-tracking, then even evolutionary theory, being a product of human reasoning, is not reliable; given that “EDAs themselves are based on scientific theories, notably evolutionary theory, and philosophical reflection” (De Cruz et al. 2011, p. 525), then EDAs themselves are not reliable, nor truth-tracking, and so are self-defeating.

            This objection to EDAs is similar to Reuben Hersh’s objection to the claim that, by Gödel’s second incompleteness theorem, the purpose of mathematical logic to give a secure foundation for mathematics cannot be achieved, and then mathematics cannot be said to be absolutely certain (Cellucci 2013, § 1.6). The response given by Carlo Cellucci to Hersh’s objection shows that such claim about mathematics is not self-defeating, and can be adopted to show that EDAs are not self-defeating as well.

            Hersh’s objection runs as follows: “If mathematics cannot be said to be absolutely certain, then Gödel’s second incompleteness theorem, being a mathematical result, cannot be said to be absolutely certain. But the claim that mathematics cannot be said to be absolutely certain is based on Gödel’s result. Then this claim too cannot be said to be absolutely certain. Therefore, the claim that, by Gödel’s second incompleteness theorem, mathematics cannot be said to be absolutely certain is self-defeating” (Ibidem).

            To face Hersh’s objection, Cellucci has argued that: “this objection is unjustified, because the argument that, by Gödel’s second incompleteness theorem, mathematics cannot be said to be absolutely certain, does not depend on the assumption that Gödel’s second incompleteness theorem can be said to be absolutely certain. It is a reduction to the impossible, because it is of the following kind. Let us suppose, for argument’s sake, that mathematics can be said to be absolutely certain. Then Gödel’s second incompleteness theorem, being a mathematical result, can be said to be absolutely certain. But, by Gödel’s second incompleteness theorem, mathematics cannot be said to be absolutely certain. Thus mathematics cannot be said to be absolutely certain. Contradiction. Therefore mathematics cannot be said to be absolutely certain” (Ibidem).

            So, it is possible to restate De Cruz’s objection (o) and propose a Cellucci-style response (r) to such objection, as follows: (o) if human scientific reasoning cannot be said to be truth-tracking, then EDAs, being based on human scientific reasoning, cannot be said to be truth-tracking. But the claim that human scientific reasoning cannot be said to be truth-tracking is based on EDAs. Then this claim too cannot be said to be truth-tracking. Therefore, the claim that, by EDAs, human scientific reasoning cannot be said to be truth-tracking is self-defeating; (r) this objection is unjustified, because the argument that, by EDAs, human scientific reasoning cannot be said to be truth-tracking does not depend on the assumption that EDAs can be said to be truth-tracking. It is a reduction to the impossible, because it is of the following kind. Let us suppose, for argument’s sake, that scientific reasoning can be said to be truth-tracking. Then evolutionary theory can be said to be truth-tracking. Then EDAs, being based on evolutionary theory, can be said to be truth-tracking. But, by EDAs, human scientific reasoning cannot be said to be truth-tracking. Thus evolutionary theory cannot be said to be truth-tracking. Contradiction. Therefore human scientific reasoning cannot be said to be truth-tracking.

            So, since adopting the argument described above the claim that, by EDAs, human scientific reasoning cannot be said to be truth-tracking can be shown not to be a self-defeating claim, then such argument shows that EDAs are not self-defeating arguments.

Fabio Sterpetti

Bibliography

Cellucci, C. (2013): Rethinking Logic. Logic in Relation to Mathematics, Evolution, and Method, Dordrecht, Springer.

De Cruz, H.; Boudry, M.; De Smedt, J.; Blancke, S. (2011): Evolutionary Approaches to Epistemic Justification, Dialectica, vol. 65, no. 4, pp. 517-535.

Kahane, G. (2011): Evolutionary Debunking Arguments, Noûs, vol. 45, no. 1, pp. 103-125.

Severini, E.: Review of Driscoll, C., “Can Behaviors Be Adaptation?”

In Philosophy of Biology, Review, Severini on March 22, 2013 at 8:01 AM

Although sociobiology (SB) and evolutionary psychology (EP) are not competitor projects, they must be integrated, argues Driscoll: according to her both psychological mechanisms and behaviors represent kinds of adaptation. In order to achieve an integrate theory, she focuses her discussion on an Sterelny & Griffiths’ idea (Sterelny 1992; Sterelny & Griffiths 1999), for whom SB’s attempt to identify evolutionary explanation for discrete units of human behavior is substantially wrong. Since the relation between psychological mechanisms and produced behaviors is one-to-many, each behavioral change (e.g., B1) cannot exist without a relative change in the mechanism that produced it, which then produces other behaviors’ changes (B2, B3…). Therefore, none behavior is supposed to evolve independently of others, thus it cannot be an adaptation. According to Driscoll’s analysis, there are mainly two objections to this reasoning. First of all, this argument relies on a too strong interpretation of Lewontin’s quasi-independence criterion (QIC). On the contrary, there should be at least one way to change T-trait such that the positive contribution to an organism’s fitness is greater than the total negative contribution supplied by any connected trait: in this way a trait can be considered under natural selection. The latter is that merely possession of a mechanism supporting different behaviors does not imply that changes in one behavior make necessary changes in others. Otherwise, an identical mechanism should manage different inputs in order to produce as many different outputs as it is possible. Seems to me that both these objections are unsatisfactory: as a matter of fact, Driscoll’s interpretation of QIC (Brosnan 2009) does not solve the mereology problem about how legitimately identifying behavioral units; the second objection, relying on a strong computational model of human psychology, can be theoretically assumed but not empirically supported.

Bibliography

Brosnan, K. (2009), Quasi-independence, fitness, and advantageousness, Studies in History and Philosophy of Biological and Biomedical Sciences, 40, 228–234 http://www.sciencedirect.com/science/article/pii/S1369848609000351

Driscoll, C. (2004), Can behaviors be adaptations?, Philosophy of Science, 71, 16–35. http://www.jstor.org/discover/10.1086/381410?uid=3738296&uid=2134&uid=2&uid=70&uid=4&sid=21101593659077

Sterelny, K. (1992), Evolutionary explanations of human behavior, Australian Journal of Philosophy, 70 (2), 156–172. http://www.tandfonline.com/doi/abs/10.1080/00048409212345051

Sterelny, K. & Griffiths, P. (1999), Sex and death, Chicago: University of Chicago Press. http://www.amazon.co.uk/Sex-Death-Introduction-Philosophy-Foundations/dp/0226773043

Could plasticity provide an evolutionary understanding of variation?

In Fabris, Philosophy of Biology on December 4, 2012 at 7:00 AM

C.H.Waddington’s genetic approach still remains contemporary, after more than half of a century from its first exposition. The reason of this is mainly because it sheds light on the organism/environment regulatory mechanisms that can step up the explanation of the morphological variations that we observe everywhere in the biological realms. Waddington was the first scholar showing how the selection of biological responses to a particular environmental stimulus influence  the direction of the evolutionary change (Waddington, 1953). In the last decade,s several authors stressed the necessity to expand the epistemological boundaries of the Modern Synthesis (e.g. Pigliucci, 2007). By this point of view, the integration –as Waddington first displayed– of ontogeny and development into evolutionary explanations may result essential for understanding the biological significance of  phenotypic  novelties. Adopting such EvoDevo approach, genetics and molecular biology concur to demonstrate how “regulation” and “organism/environment feedback” play a crucial role in expressing phenotypical variation (Hiyama et al., 2012). By this line of evidences, blowing up by the Waddington’s pioneristic work, emerge how the environmental changes may have some relevant effects, not merely selective as claimed by the neo-Darwinian tradition, in promoting the evolution of the genome. Irrespectively by the extend of these effects, we must then consider the genetic and epigenetic responses exhibited by the organisms as phenotypical cues of deeper evolutionary refinements and/or switching occurring in previous canalized pathways of development. However, the comprehension of the full range of genomics plasticity is not alone suffice to provide a satisfactory evolutionary understanding of the phenomenon of morphological variation. A balance between the capacity of the genome to respond plastically to the environmental stimuli and the adaptive “opportunity” to reveal mutations, need to occur at some point of the complex organism/environment interaction. If this not the case, we have a paradox by which the mechanisms responsible for the phenomena of phenotypical variation could lead not to evolutionary adaptation, but rather to an opposite effect.       

Bibliography 

Hiyama, A., Taira, W., & Otaki, J. M. (2012). Color-pattern evolution in response to environmental stress in butterflies. Frontiers in genetics, 3, 1-6.

Pigliucci, M. (2007). Do we need an extended evolutionary synthesis? Evolution, 61, 2743-2749.

 Waddington, C. H. (1953). Genetic assimilation of an acquired character. Evolution, 7, 118-12  

Flavia Fabris