This paper proposes an abstract mathematical frame for describing some features of biological time. The key point is that usual physical (linear) representation of time is insufficient, in our view, for the understanding key phenomena of life, such as rhythms, both physical (circadian, seasonal …) and properly biological (heart beating, respiration, metabolic …). In particular, the role of biological rhythms do not seem to have any counterpart in mathematical formalization of physical clocks, which are based on frequencies along the usual (...) (possibly thermodynamical, thus oriented) time. We then suggest a functional representation of biological time by a 2-dimensional manifold as a mathematical frame for accommodating autonomous biological rhythms. The “visual” representation of rhythms so obtained, in particular heart beatings, will provide, by a few examples, hints towards possible applications of our approach to the understanding of interspecific differences or intraspecific pathologies. The 3- dimensional embedding space, needed for purely mathematical reasons, allows to introduce a suitable extra-dimension for “representation time”, with a cognitive significance. (shrink)

Qu'est-ce qu'une espèce? Comment se développe un embryon? Comment comprendre l'obésité, le cancer ou le sida? Les progrès de la biologie moléculaire nous ont persuadés que, tel un démiurge tout puissant, le génome crée l'organisme et en constitue l'explication ultime. Deux chercheurs montrent ici, de la molécule à l'Homme, en passant par les cellules et les virus, que règne moins la dictature d'un dieu-programme inscrit dans l'ADN qu'un hasard permanent, guidé par la sélection naturelle. Nous ne sommes plus, depuis Copernic, (...) au centre de l'univers, ni depuis Darwin, au sommet de la création. Voilà que nous ne sommes pas le centre, ni la finalité de notre propre organisme, mais une société décentralisée de cellules. Ni Dieu ni gène... Le déterminisme fait place à la liberté et la biologie n'en devient que plus passionnante. (shrink)

The main focus of the book is the presentation of the 'inertial' view of population growth. This view provides a rather simple model for complex population dynamics, and is achieved at the level of the single species without invoking species interactions. An important part of this account is the maternal effect. Investment of mothers in the quality of their daughters makes the rate of reproduction of the current generation depend not only on the current environment, but also on the environment (...) experienced by the previous generation. (shrink)