Abstract

IntroductionThe observation that animals may respond to emotional states of conspecific or even hetero-specific individuals is not new. Darwin broached the question by underlying the ability of animals to express sympathy, i.e. the response to non-self-emotional status, and this across species barriers. More importantly, he tried to find the evolutionary origin of this animal trait, suggesting that it evolved from the selective advantages of kinship behaviour in the struggle for life (Darwin, 1872). Such a behaviour corresponds, for instance, to alloparental care relatively common in mammals and birds, and now also characterized in fishes and insects (Josi, Taborsky, & Frommen, 2019; Wu, Walser, Sun, & Kölliker, 2020). After more than one century, the need of defining what exactly non-human animals are able to feel, and from this starting point, rethink the legal status and place of animals in human societies, suddenly arises. This can mainly be considered as an indirect consequence of people awareness of human-driven dramatic impacts on global climate, biodiversity, but also on a more daily basis on animal life and welfare. However, because assessable currencies are required to establish laws, animals were classified into categories based on ecological (e.g. invasive species, pest, wild, domestic), biological (e.g. vertebrates and invertebrates) or cognitive (e.g. primates, cephalopods) traits. This should help lawyers to define ethical rules of animal use by humans and t...