Humans and climate as possible drivers of the morphology and function of the mandible of Suncus etruscus in Corsica

Abstract

Human-induced environmental changes have increased rapidly during the Holocene and have reached alarming levels today. Consequently, it is crucial to better understand the impact of humans and climate on the faunas and floras through time. Understanding the direct and underlying effect of past human activity not only contributes to improving our knowledge of human history but also provides insights for the future. We here investigate the effect of the human-induced environmental changes that took place during the modern era (14–19th century AD) on the mandible of a small mammal, Suncus etruscus, in Corsica. We detected rapid morphological changes in mandible shape over the relatively short period of time included in our study, suggesting a strong human impact on the island. The morphological changes observed had functional consequences as they are related to changes in the mechanical potential of the principal masticatory muscle, the temporalis that, in turn, reflects shifts in the animal's diet over time. These results highlight the effect that the 600-year human agricultural activity shifts had on the island and its fauna. The integration of the body and the ramus of the mandible appears to be related to the mechanical potential of the temporalis muscle but does not constitute an indicator of human-induced environmental change. Whether these morphological changes are the result of natural selection (genetic processes) or of phenotypic plasticity (epigenetic processes) remains to be elucidated.