Archivi categoria: Contributions to international conferences

A new look at the Extended Evolutionary Synthesis

emanuele-sibe2013I present the initiatives, papers, and ideas of Pigliucci, Müller, and others, who are proposing an Extended Evolutionary Synthesis (EES). I then advance some reasons for concern raised by those claims, including uncertainties in timing, historical inaccuracies, lack of a theoretical structure, arbitrariness and instability of the included concepts, stereotypical characterization of the Modern Synthesis, and dissent among evolutionary biologists. Then I mention the studies by historian of the Modern Synthesis, Joe Cain, who is very detailed and careful in explaining that Mayr, Dobzhansky, Huxley & co. who claimed they were part of a Modern Synthesis, they did also for strategic and political reasons, related to their own careers and to more general cultural battles of the time. What I want to argue is not that the Modern Synthesis was an invented product of a marketing operation; rather, it is that the social and interactive dynamics of science are very important in understanding what is going on. The same could be true for the EES in our years. I maintain the primary importance of understanding how biology is today, how it has changed, what future expects us. Pigliucci’s question, “Do we need an EES?”, thus suggests very important issues. But I propose that we shouldn’t take at face value what the protagonists of evolutionary biology see and say. The ‘expert review’ or the ‘small group of architects’ methods cannot work. No solution either comes from a traditional philosophical approach of ‘describing the structure of evolutionary theory’, because scientists don’t work ‘inside’ theories; they use them in different ways. Correct methods for answering could be developed, with the help of advanced technology for analyzing the scientific literature, the ways of doing science, the ‘hot topics’, the birth and death of fields, etc., through time. This would mean to look seriously at the scientific community, avoiding, on t he one hand, the authority principle, and, on the other hand, the surrender to an ‘all flows, everything ever changes’ perspective. In the context of such an endeavour, I suggest a specific look at the Italian evolutionary biology community as important for the future prospects of this science in our country.

Look for it in the Publications page (with additional links):

Serrelli E (2013). A new look at the Extended Evolutionary Synthesis. 5th congress of the Italian Society for Evolutionary Biology (SIBE). Trento, Faculty of Lettere and MUSE Museum, Italy, August 28-31. []

Phenotypic variation in ecological setting

phenotypic-ecological.035Organisms are niche constructors: they impact the environment and modify selective pressures that direct their own evolution as well as that of their non-conspecific fellows in ecological systems at various scales. The theoretical acknowledgement of niche construction has inspired many reflections about the active role of organisms in evolution, often proclaiming a revolutionary theoretical change. But if we look at formal models the claim is not yet justified. Ecologists have specified population-scale models of niche construction, but these cannot be adopted as evolutionary models: they don’t incorporate heritable variation nor allow for directional selection and cumulative change. As evolutionists point out, these models are mere phenotype dynamics or population fluctuations with different possible outcomes – extinction or sustainability. Evolutionary models of niche construction, on the other hand, are not so revolutionary in their foundations, often being just classical population genetics provided with feedback loops between loci and selective pressures acting on them. The idea that variation among organisms boils down to genetic differences captured by gene frequencies dates back to the heart of the Modern Synthesis. But niche construction points directly to the world of physical and chemical interactions. This is the world where resource-impacting phenotypes are built through developmental processes, in turn subject and sensitive to the surrounding environment and the resources left over by previous generations. The produced phenotypes and their effects are hardly summarized by gene frequencies, yet evolutionary models need some kind of heritable variation and selection. The future challenge of evolutionary modeling beyond the Modern Synthesis is thus ecological, plastic variation that allows for inheritance with varying degrees and not-always-allelic mechanisms.

Session: Understanding variation beyond the Modern Synthesis

Look for it in the Publications page (with additional links):

Serrelli E (2013). Phenotypic variation in ecological setting: a challenge for evolutionary modeling beyond the Modern Synthesis. Meeting of the International Society for History, Philosophy, and Social Studies of Biology (ISHPSSB), Montpellier, France, July 7-11. []


The challenge of tree-thinking and network-thinking

This talk gives a reflexive outlook on the employment of tree and network thinking to conceptualize and model vertical descent and horizontal transmission of cultural traits. In biology, evolutionary trees are more than tools for researchers across disciplines: they are the main framework within which evidence for evolution is evaluated (Baum et al. 2005). However, several biologists have recognized “tree thinking” as a challenge for students (Gregory 2008, Meisel 2010), lay people (Baum, cit.), and scientists alike (O’Hara 1992), going against our spontaneous cognitive tendencies, e.g., reading along the tips, locating evolution only at nodes, projecting living species backwards to internal nodes. Moreover, common descent, represented by trees, is not the only way in which biological traits are shared: the ubiquity of phenomena like lateral gene transfer is increasing the need for network-based analyses, introducing the conceptual challenge of “network thinking” (Proulx et al. 2005), and the further complexity of conceiving trees and networks together. I focus on which strategies, used and developed in biology, can be implemented in anthropology to address cultural relatedness and common ancestry relationships.

Baum DA et al. (2005). The tree-thinking challenge. Science 310(5750):979-980.
Gregory TR (2008). Understanding evolutionary trees. Evolution: Education and Outreach 1(2):121-137.
Meisel RP (2010). Teaching tree-thinking to undergraduate biology students. Evolution: Education and Outreach 3(4):621-628.
O’Hara RJ (1992). Telling the tree: Narrative representation and the study of evolutionary history. Biology and Philosophy 7(2):p.135–160.
Proulx SR et al. (2005). Network thinking in ecology and evolution. Trends in Ecology and Evolution 20(6):345-53.

Emanuele is also moderator and, with Nathalie Gontier, co-organizer of the session: Tree and network models in San Francisco.

Look for it in the Publications page (with additional links):

Serrelli E (2012). The challenge of tree-thinking and network-thinking: conceptual issues across biological and cultural domains. Paper at 2012 Annual Meeting of the American Anthropological Association, San Francisco, CA, November 14-18. []

Adaptive vs exaptive in the evolution of human language

Evolutionary Biology Meeting, MarseillesThe poster was presented by Irene Berra.

Human articulate language doesn’t involve clearly distinguishable structures and substructures but shows distributed functions. Clues coming from brain comparative studies and neuroimaging point out that cortical structures and connections have been re-functionalized during the evolution of primates and hominids, due to their plasticity and learning capacity. But also the expression of FoxP2 in basal ganglia is involved in vocal and sequential learning. However, neither vocal-learning mammals (whales, dolphins and bats) nor song-learning birds share the human amino acid substitutions (Webb and Zhang, J. Hered., 96, 2005). Language evolution is likely to be a recruitment, with slight modifications, of pre-existing genetic cascades that have other regulatory functions. An exaptive hypothesis has been proposed for acoustic communication during water-to-land transition, as in the case of limbs. Comparative analyses within living species are being conducted to test this hypothesis (Polgar et al., PLoS ONE, 6, 2011) and these may be cases of convergent exaptation. The term was introduced by Gould and Vrba (Paleobiology, 8, 1982) and was blamed of non-operationalizability. Our view (Pievani & Serrelli, Journal of Anthropological Sciences, 89, 2011) is that exaptive hypotheses can be operationalized and improved, and recent research in language evolution offers a good example. We should, e.g., distinguish theories of neural reuse, recycling and re-functionalization (Anderson, Behav. Brain Sciences, 33, 2010) from exaptation when they concern developmental rather than evolutionary processes. Aside from neurobiological studies of language, the exaptationist account is still too speculative (e.g. in anthropology). Enlarging the phylogenetic context, improving technology to identify structures, and attempting the reconstruction of environmental settings to match fitness utility help the historical comprehension of the series of etho-ecological functions of language.

The Evolutionary Biology Meeting at Marseilles is an annual congress which has gathered high level experts in evolutionary biology since its creation in 1997. If the congress was initially a local meeting, it quickly gained an important weight in the scientific life. Indeed, whereas the number of participants has been increasing, the geographical origin of the researchers has been diversifying and widening year by year. Today, the Evolutionary Biology Meeting at Marseilles has reached a worldwide dimension and plays a paramount role in the international scientific life: allowing the gathering of high level specialists, it encourages the exchange of ideas and stimulates the works of the researchers all through the world.

Look for it in the Publications page (with additional links):

Berra I, Pievani T, Serrelli E (2012). How to test adaptive vs exaptive evolutionary hypotheses: the case of human language. Poster at 16th Evolutionary Biology Meeting, Marseilles, France, September 18-21. []

Criticizing adaptive landscapes, ecology and genealogy

Disentangling ecological vs. genealogical dimensions is a core task of hierarchy theory in evolutionary biology. As Eldredge repeatedly epitomized, organisms carry out (only) two distinct kinds of activities: they survive, and they reproduce.
At the organismal level, the organism stays the same whether we consider it ecologically or genealogically – yet, differences can occur in what features we consider relevant, and what fitness measurement we use.
At higher levels, the two dimensions diverge, realizing different systems. Reproductive (deme) may not coincide with ecological (avatar) population. Further upwards, along the ecological dimension, higher-level systems are grouped by energy- matter interconnection, whereas, along the genealogical dimension, higher taxa are assembled by relatedness.
In Dobzhansky’s (1937) use of the adaptive landscape visualization (Wright 1932), all living species are imagined as distributed on adaptive peaks which correspond to ecological niches in existing environments. Peaks are grouped forming genera and higher taxa (e.g., “feline”, “carnivore” ranges), and geographic speciation is figured out – like adaptation – as movement on the landscape.
In criticizing Dobzhansky’s landscape, Eldredge wrote that species actually do not occupy ecological niches; demes don’t, either; avatars do.
I point out that neighborhood and movement need to be conceived separately in genealogical and ecological spaces. Indeed, ecology should be further split in at least two spaces: geographic and phenotypic/adaptive. Movement in one space may in fact result in stability in the other(s).
I also comment on the adaptive landscape: technical limitations prevent it from being coherently used above the population level, even though as a metaphor. Finally, I emphasize the partiality of any landscape – based on the choice of relevant features and fitness components – and interpret partiality as the way of approaching complex multi- hierarchical structure in evolution.

Emanuele is also organizer of the “Hierarchy theory” session at the conference.

Look for it in the Publications page (with additional links):

Serrelli E (2011). Criticizing adaptive landscapes and the conflation between ecology and genealogy. Meeting of the International Society for History, Philosophy, and Social Studies of Biology (ISHPSSB), Salt Lake City (Utah, USA), July 10-16. []