Zimmer M.,EPHE Paris
European Journal of Anaesthesiology | Year: 2014
The direct application of volatile anaesthetic and the application of intense cold to traumatic injuries and surgical sites were important steps in 18th and 19th century anaesthesia. Local tissue temperature could be brought down by the application of ice and salt by the surgeon. Techniques used topical applications of chloroform, Dutch Oil, amyl hydrate, the vaporisation of nebulised ether, methylene and ethylene chloride applied by spray or fumigation and vaginal douche with carbonic acid gas. Mastering the projection of cold was extremely difficult. Keeping the aperture of the device used for the spraying of anaesthetic liquids clear of obstruction became a major challenge for instrument makers. To improve the precision of the jet, a different system of nozzles had to be invented. Nineteenth century medical practitioners were able to call on general anaesthesia, but some individuals and specific indications such as minor surgery called for an alternative approach. The introduction of cocaine in 1884 completely changed common practice.
Veuille M.,EPHE Paris
Comptes Rendus - Biologies | Year: 2010
Darwin's book on the Descent of Man and Selection in Relation to Sex (1871) is often viewed as the continuation of The Origin of Species published 12 years earlier (1859), both because of the implicit parallelism between natural selection and sexual selection, and because Darwin himself presents the book as developing a subject (man) which he intentionally omitted in the Origin. But the Descent can also be viewed as the continuation of his book on Variation published three years earlier (1868). Firstly because Darwin's hypothesis of pangenesis links the selection process to the origin of variation through use and disuse, an idea underlying his speculations on the origin of moral sense in humans. Second because like the action of the horticulturist on his domestic crops, sexual selection exerted by one sex on the other sex can develop fancy traits that are not easily accounted for by their utility to the selected organism itself, such as artistic taste, pride, courage, and the morphological differences between human populations. These traits are difficult to reconcile with pangenesis. They add up to other contradictions of the book possibly resulting from Darwin's erroneous inference about the mechanism of inheritance, like those on the determination of sex-ratio, or the confusion between individual adaptation and the advantage to the species. These inconsistencies inaugurate a weakening of the Darwinian message, which will last 50 years after his death. They contributed to the neglect of sexual selection for a century. Darwin however maintained a logical distinction between evolutionary mechanisms and hereditary mechanisms, and an epistemological distinction between evolutionary theory and Pangenesis hypothesis. In the modern context of Mendelian genetics, Darwin's sexual selection retrospectively appears as luminous an idea in its pure principle as natural selection, even though the mechanisms governing the evolution of sexual choice in animals remain largely unresolved. © 2009 Académie des sciences.
Santos X.,University of Porto |
Cheylan M.,EPHE Paris
Biological Conservation | Year: 2013
Wildfires are common disturbances that have a major impact on ecosystems. Recent decades have seen an increase in fire frequency and extension due to the combined effects of climate change and land-use history. We studied the taxonomic and functional response of a reptile assemblage to repeated fires in southern France to understand shifts in dominant species and diversity, as well as the mechanisms that underlie responses according to functional traits of species. In the spring of 2010, we sampled reptiles in areas with three types of fire regime: unburned, burned once (2003) and burned 4-5 times (last fire in 2003) along a fire history of 51-years period. With this field sampling design, we examined the intermediate disturbance hypothesis and the habitat accommodation model of succession as methods to predict reptile responses to natural fire regimes. We also compared habitat structure at the study area between 1944 and 2006 to certify that repeated-fire regimes have modified the habitat for reptiles. The comparison of the habitat structure between both periods demonstrated that repeated-fire regimes modified the landscape from a homogeneous sparse forest to a contrasted heterogeneous mixture of scrubland and dense forest. We found a loss of reptile diversity after one and multiple fires, a result that contradicts the intermediate disturbance hypothesis. Reptile composition differed among the three fire regimes: there was a shift in dominant species and a reduction of beta diversity related to an increase in the number of fires. We also observed a functional response to repeated fires, with an increased frequency of insectivorous reptiles, which live in open areas, are specialists in their ecological niche, and have a short lifespan. These results suggest that reptile replacement according to fire regime accounts for a habitat accommodation model following particular traits of species. Our study indicated that areas subjected to repeated fires have a more strictly Mediterranean reptile assemblage than unburned areas, due to the ability of Mediterranean species to survive thermal environments in open (burned) areas. At a regional scale, changes in dominant species between unburned and repeatedly burned areas might be an argument for maintaining a patchwork of areas burned at variable intervals. However, the increase in fire frequency and extension suggests a future scenario of extinction for species negatively impacted by fire, such as the endangered Hermann's tortoise Testudo hermanni, for which the study area is home to one of the last native populations in the western Mediterranean. © 2013 Elsevier Ltd.
Paldi A.,EPHE Paris
Epigenomics | Year: 2013
The increasing popularity of stem cells in life science research has at least two major causes. On one hand, the study of stem cells may provide insights into one of the major secrets of biology: the mechanisms of cell differentiation. On the other hand, stem cells are potentially promising tools for regenerative therapy. The understanding of how environmental stimuli are translated into phenotypic differentiation through gene expression changes and how the same stimuli at the same time may perturb the normal process of cellular differentiation, growth and maintenance is a central issue for fundamental research but is also essential for the development of efficient and safe procedures for therapeutic use. This article assembles the known facts, as pieces of a puzzle, into a coherent picture around the idea of why stem cells are so sensitive to their culture environment and what practical consequences this implies. © 2013 Future Medicine Ltd.
Gerber S.,EPHE Paris
Biological Reviews | Year: 2016
Morphospaces are spatial depictions of morphological variation among biological forms that have become an integral part of the analytical toolkit of evolutionary biologists and palaeobiologists. Nevertheless, the term morphospace brings together a great variety of spaces with different geometries. In particular, many morphospaces lack the metric properties underlying the notions of distance and direction, which are, however, central to the analysis of morphological differences and evolutionary transitions. The problem is illustrated here with the iconic morphospace of coiled shells implemented by Raup 50years ago. The model, which allows the description of shell coiling geometry of various invertebrate taxa, is a seminal reference in theoretical morphology and morphospace theory, but also a morphometric framework frequently used in empirical studies, particularly of ammonoids. Because of the definition of its underlying parameters, Raup's morphospace does not possess a Euclidean structure and a meaningful interpretation of the spread and spacing of taxa within it is not guaranteed. Focusing on the region of the morphospace occupied by most ammonoids, I detail a landmark-based morphospace circumventing this problem and built from the same input measurements required for the calculation of Raup's parameters. From simulations and a reanalysis of Palaeozoic ammonoid shell disparity, the properties of these morphospaces are compared and their algebraic and geometric relationships highlighted. While Raup's model remains a valuable tool for describing ammonoid shells and relating their shapes to the coiling process, it is demonstrated that quantitative analyses of morphological patterns should be carried out within the landmark-based framework. Beyond this specific case, the increasing use and diversity of morphospaces in evolutionary morphology call for caution when interpreting patterns and comparing results drawn from different types of morphospaces. © 2016 Cambridge Philosophical Society.