A Comparison of the Effects of Random and Selective Mass Extinctions on Erosion of Evolutionary History in Communities of Digital Organisms

The effect of mass extinctions on phylogenetic diversity and branching history of clades remains poorly understood in paleobiology. We examined the phylogenies of communities of digital organisms undergoing open-ended evolution as we subjected them to instantaneous “pulse” extinctions, choosing survivors at random, and to prolonged “press” extinctions involving a period of low resource availability. We measured age of the phylogenetic root and tree stemminess, and evaluated how branching history of the phylogenetic trees was affected by the extinction treatments. We found that strong random (pulse) and strong selective extinction (press) both left clear long-term signatures in root age distribution and tree stemminess, and eroded deep branching history to a greater degree than did weak extinction and control treatments. The widely-used Pybus-Harvey gamma statistic showed a clear short-term response to extinction and recovery, but differences between treatments diminished over time and did not show a long-term signature. The characteristics of post-extinction phylogenies were often affected as much by the recovery interval as by the extinction episode itself

The Crisis of Historicism: Neo-Kantian Philosophy of History and Wilhelm Dilthey's Hermeneutics.

The development of historical consciousness is a phenomenon which has had a profound effect on the growth of the "social" and "human" sciences in the last two hundred years. In Germany especially, not only historians but also other pracitioners of the human sciences have adopted a new historical approach in underst and ing their subject matter and method. These "historicists," as they have been called, offered a new model of truth for scientific inquiry, one rooted not in the logical-mathematical method of the natural sciences but in the vital, lived-experience of human history. For two generations in Germany, philosophers and historians engaged in a powerful debate on questions of historical truth and scientific method: what made history "scientific"? Was its scientific character based on the model of natural scientific logic? Did history have its own logic of science? Or was the "scientific" itself historical, limited and relative? These were the questions which moved German thinkers in the period from 1860 to 1930 in their debate on "the crisis of historicism." This thesis focuses in particular on the controversy between the Neo-Kantian school of philosophy (Heinrich Rickert and Wilhelm Windelb and ) and the philosophy of Wilhelm Dilthey. Whereas Rickert and Windelb and attempted to solve the problem of historical relativism by offering a theory of transcendental value, Dilthey countered by providing a hermeneutic critique of historical reason. A summary of the historicist legacy from Herder and Hegel to Ranke and Droysen is provided which attempts to show that historicism is less the product of a romantic, anti-Enlightenment sensibility than it is the offspring of a Cartesian-Kantian underst and ing of scientific truth and method. The development of this Neo-Kantian tradition is analyzed to show the close connection between Kant's theory of nature and the new theory of history. The problem of scientific objectivity in Windelb and and Rickert is discussed and an extensive analysis of Wilhelm Dilthey's hermeneutics as a way out of the cul-de-sac of historical relativism is presented. A way to bridge the gap between nineteenth century historicism and the hermeneutical theory of Martin Heidegger and Hans-Georg Gadamer is offered.Ph.D.European historyUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/161510/1/8720241.pd