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Ghirlanda, S., Frasnelli, E., & Vallortigara, G. (2009). Intraspecific competition and coordination in the evolution of lateralization. Phil. Trans. Biol. Sci., 364(1519), 861–866.
Abstract: Recent studies have revealed a variety of left–right asymmetries among vertebrates and invertebrates. In many species, left- and right-lateralized individuals coexist, but in unequal numbers (‘population-level’ lateralization). It has been argued that brain lateralization increases individual efficiency (e.g. avoiding unnecessary duplication of neural circuitry and reducing interference between functions), thus counteracting the ecological disadvantages of lateral biases in behaviour (making individual behaviour more predictable to other organisms). However, individual efficiency does not require a definite proportion of left- and right-lateralized individuals. Thus, such arguments do not explain population-level lateralization. We have previously shown that, in the context of prey–predator interactions, population-level lateralization can arise as an evolutionarily stable strategy when individually asymmetrical organisms must coordinate their behaviour with that of other asymmetrical organisms. Here, we extend our model showing that populations consisting of left- and right-lateralized individuals in unequal numbers can be evolutionarily stable, based solely on strategic factors arising from the balance between antagonistic (competitive) and synergistic (cooperative) interactions.
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Ghirlanda, S., & Vallortigara, G. (2004). The evolution of brain lateralization: a game-theoretical analysis of population structure. Proceedings of the Royal Society of London. Series B: Biological Sciences, 271(1541), 853–857.
Abstract: In recent years, it has become apparent that behavioural and brain lateralization at the population level is the rule rather than the exception among vertebrates. The study of these phenomena has so far been the province of neurology and neuropsychology. Here, we show how such research can be integrated with evolutionary biology to understand lateralization more fully. In particular, we address the fact that, within a species, left– and right–type individuals often occur in proportions different from one–half (e.g. hand use in humans). The traditional explanations offered for lateralization of brain function (that it may avoid unnecessary duplication of neural circuitry and reduce interference between functions) cannot account for this fact, because increased individual efficiency is unrelated to the alignment of lateralization at the population level. A further puzzle is that such an alignment may even be disadvantageous, as it makes individual behaviour more predictable to other organisms. Here, we show that alignment of the direction of behavioural asymmetries in a population can arise as an evolutionarily stable strategy when individual asymmetrical organisms must coordinate their behaviour with that of other asymmetrical organisms. Brain and behavioural lateralization, as we know it in humans and other vertebrates, may have evolved under basically ‘social’ selection pressures.
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