A recent study published in the scientific journal iScience reveals that turtles are the first known vertebrates to use two different mechanisms for forming head scales: one based on genetic signals and another purely mechanical. This discovery enhances our understanding of evolution and opens doors for technological innovations.
Traditionally, skin structures like scales, feathers, and hair in vertebrates originate from placodes, specialized regions of the epidermis controlled by highly conserved genetic signals. However, crocodiles present an exception: their head scales form through physical folding of the growing skin. Scientists at the University of Geneva (UNIGE) have now discovered that turtles combine both processes, an unprecedented approach among vertebrates.
Using 3D light-sheet microscopy and computational modeling, the team demonstrated that simple physical forces are sufficient to generate the irregular patterns observed in turtle scales. The simulated models, adjusting parameters such as tissue stiffness and growth rate, managed to replicate the actual scaly shapes seen in different turtle species. This finding challenges traditional paradigms of developmental biology.
From an evolutionary perspective, turtles (Testudinata) are the closest living relatives of crocodiles and birds. The fact that turtles and crocodiles share the physical mechanism for scale formation suggests that this is an ancestral trait, present in the last common ancestor of the group. This research highlights the active role of physics in morphogenesis, the biological process that causes an organism to develop its shape.
Beyond its academic impact, this study opens doors for technological innovations. By understanding how nature creates complex structures based on simple physical rules, opportunities arise for advances in biomimicry, regenerative medicine, and materials design. This research demonstrates how mechanical folding can shape biological patterns, offering practical solutions inspired by nature.