Organisms are faced with variable environments and one of the most common solutions to cope with such variability is phenotypic plasticity, a modification of the phenotype to the environment. These modifications are commonly modelled in evolutionary theories as adaptive, influencing ecological and evolutionary processes. If plasticity is adaptive, we would predict that the closer to fitness a trait is, the less plastic it would be. To test this hypothesis, we conducted a meta-analysis of 213 studies and measured the plasticity of each reported trait as a coefficient of variation. Traits were categorized as closer to fitness—life-history traits including reproduction and survival related traits, and farther from fitness—non-life-history traits including traits related to development, metabolism and physiology, morphology and behaviour. Our results showed, unexpectedly, that although traits differed in their amounts of plasticity, trait plasticity was not related to its proximity to fitness. These findings were independent of taxonomic groups or environmental types assessed. We caution against general expectations that plasticity is adaptive, as assumed by many models of its evolution. More studies are needed that test the adaptive nature of plasticity, and additional theoretical explorations on adaptive and non-adaptive plasticity are encouraged.

Organisms are faced with variable environments and one of the most common solutions to cope with such variability is phenotypic plasticity, a modification of the phenotype to the environment. These modifications influence ecological and evolutionary processes and are assumed to be adaptive. The assumption of adaptive plasticity allows to derive the prediction that the closer to fitness a trait is, the less plastic it would be. To test this hypothesis, we conducted a meta-analysis of 213 studies and measured the plasticity of each reported trait as coefficient of variation (CV). Traits were categorised according to their relationship to fitness into life-history traits (LHt) including reproduction and survival related-traits, and non-life-history traits (N-LHt) including traits related to development, metabolism and physiology, morphology and behaviour. Our results showed, unexpectedly, that although traits differed in their amounts of plasticity, trait plasticity did not correlate with its proximity to fitness. These findings were independent of taxonomic groups or environmental types assessed and raise questions about the ubiquity of adaptive plasticity. We caution about generalising the assumption that all plasticity is adaptive with respect to evolutionary and ecological population processes. More studies are needed that test the adaptive nature of plasticity, and additional theoretical explorations on adaptive and non-adaptive plasticity are encouraged.

Before the establishment of political societies there was no constant property and social groups were not governed by an authority. Human aggregation leads into the need for authority and culture conceptualization. Inter and intra-specific interactions have evolved in parallel to the redefinition of these concepts which have always been density dependent. Present human western (or westernized) society lives in big intra-specific aggregations where constant property covers even other species, and where anthropocentrism is in general well accepted and not challenged. As communities keep growing, social pressures and other factors have made human primates away from empathy, which declines proportionally to density increase. The lack of empathy immediately drives to the search of differentiation and uniqueness which is easier to proclaim towards other species, especially to non-human primates as they could represent a threat for its resemblance to our species. All non-human animals have been cast aside, their differences highlighted and the concept of culture redefined in order to take away non-human species the possibility to have a culture. However, there are still human communities which preserve empathy towards other species, accepting non-human cultures; and who are in their search of intra and inter-specific balance. Challenging cultural anthropocentrism and non-human animal property by understanding the inter-specific balance can be achieved by a better understanding of such human communities.