Introduction

       Georges CHAPOUTHIER1 and Marie-Christine MAUREL2

       1 ICM-CNRS, Paris, France

       2 ISYEB-CNRS-MNHN, Sorbonne University, Paris, France

      One of the essential characteristics of living beings, perhaps the most important, is an explosion of their forms, linked to the extreme diversity of environments to which they have been able to adapt. It is precisely the multiplicity of these astonishing morphologies, in all its facets, that this book aims to explore.

      Of course, this diversity is rooted in the very origin of life itself, as Marie-Christine Maurel relates. The diversity of physical and chemical conditions on Earth during the Hadean period, as well as the diversity of planets and the multiple bodies of the solar system, may have led to the formation of molecules, organizations and protocells with a wide variety of shapes and metabolisms. The different chemical elements of the primitive ocean and fossil traces from the first stromatolites could provide evidence of this. Thus, biodiversity is original and current research is discovering multiple ways of “existing”, far from a standardized vision of life.

These considerations lead, of course, to the great founding question: what is life? This is what Andreas Losch tries to answer. If it is clear that, in the final analysis, living matter can be summed up as creations of physics and chemistry, and if it is true that there is no such thing as a mysterious “vital principle”, would life not then find its specificity precisely in the very explosion of its forms? But then a question of language arises. What we call “life” in everyday language, what we have an existential experience of, is not necessarily what life is at the scientific level, where material bases matter more than forms. As with other complex concepts, “life” is in fact an ill-defined combination of properties that mineral substances do not possess, where form plays a key role, and “words to describe it” are still missing. Indeed, how will “robots” and other machines describe it in a few decades?

      In living beings that are already constituted, form becomes, as Jean-Pierre Gasc shows, a means of knowledge. From Aristotle to Cuvier, function is interpreted in relation to morphology. Nowadays, more emphasis is placed on the weight of the physical framework, which suggests that form is an adaptation to environmental constraints, as evidenced for example by the symmetry of bilaterians, the appearance of even appendages (allowing “‘appendicular’ movement on land”) or the “cephalization” of mobile animals. In the second chapter, Jean-Pierre Gasc recalls the central role of the theses of the Scottish zoologist D’Arcy Wenworth Thompson, in his famous book On Growth and Form, which holds “an almost legendary place in scientific literature” and which makes