Pearson's approach is a fruitful one; Deleuze's philosophy makes use of countless biological theories and is sprinkled with biological terminology. But Pearson also explicitly argues that reducing Deleuze's project to a new philosophical biology would be incorrect. Glancing through Mille Plateaus, I suddenly noticed how easy it is to skip over the biology without the text losing value or ceasing to work. Pearson's analysis of the so-called becoming-processes in Mille Plateaus concentrates specifically on becoming-animal, leaving other fascinating processes (-music, -woman, -child, -molecular) virtually ignored. In short, this is a study with a specific entry into Deleuze, and though this specificity is of an impressive multiplicity, it automatically means that at first sight the book will interest a reasonably limited audience (more likely philosophers with an interest in biology - one of the hipper areas of knowledge at present - than biologists attracted to a Deleuzian approach). This is entirely because Pearson quite rightly makes no attempt to present the material more simply than is strictly necessary. Almost every discussion of Deleuze is 'obliged' to begin with the observation that the use of his work has increased in recent years, notably among artists and musicians. Pearson, too, touches briefly on this interest, without distancing himself from such interdisciplinary popularisations with the usual academic condescension. A critique of this tendency would also be in conflict with Deleuze's explicitly populist invitation to view his work as a toolbox. Unless this group of practical users has an explicit interest in the biophilosophical aspects of Deleuze's work, in particular the books he wrote with Guattari will remain more effective than Germinal Life.

The structure of Germinal Life is reasonably conventional. Three essays, based on the three periods in Deleuze's thought, address in different ways the question of what it means to think past the human situation. As Pearson argues, this is a troublesome question with potentially radical implications:  

The critical question to ask, and which I simply pose here, is this: Does thinking beyond the human condition serve to expand the horizons by which we think that condition and so deepen its possible experience, or is the 'change of concept' in regard to the overhuman, so dramatic that it requires the dissolution of the human form and the end of 'the human condition'?
 

Deleuze's answer is finally that his 'beyond' demands not that we leave humanity behind, but that we broaden the horizon of its experience. It is the French philosopher Bergson who convinces Deleuze that philosophy has the capacity to go beyond human experience and simultaneously is able to deepen it. As Pearson makes clear, this implies a radical reorientation of philosophy which makes use of a new logic of nuances in place of antitheses. It is Bergson's influence on Deleuze that further dominates the first chapter and forms a block in the 'pleasant reading' of Germinal Life. Pearson plays it safe here in an academic sense by unravelling the role in Deleuze of Bergson's thought for almost fifty pages, which undoubtedly makes for good philosophy, but at the same time makes for a difficult beginning in which the reader is confronted in rapid tempo with terms like 'duration' and 'élan vital' discussions of Einstein's conception of time (and what's wrong with it), and Bergson's definition of consciousness as the 'arithmetical difference between potential and real activity.'

Deleuze's 'Bergsonism' keeps reappearing in the rest of the book and is gradually modified and changed by confrontations with Freud and Nietzsche, Artaud and Zola, Simondon and Uexküll. The problem is that the central theme of biophilosophy forms a solid thread, but is also what is most easily skipped over. I would call this the problem of specificity, a problem for which we can partially blame Deleuze himself (for example, Pearson refers to the problematic character of becoming-processes, which are presented without any indication of a cultural context in which they could take place), or, in the end, chiefly philosophy in general. This is perhaps a standard critique, e.g. by sociology, of philosophy's abstract character (which at the same time is precisely its dazzling 'useless' power). It becomes clear beyond doubt to the reader that the process of evolution is open to many discussions and redefinitions, but ultimately attention is drawn with more and more pleasure to the byways of analysis - for example, how Deleuze was inspired by Fitzgerald's 'study' of destructive instincts. This is probably also a question of which angle or lines of approach one finds more interesting. Pearson's emphasis of Bergson's influence on Deleuze is perfectly accurate and instructive, but the hardcore Nietzschean in me goes on the alert when Deleuze argues that criticism must always be violent. Pearson writes about Deleuze's problem with philosophy:  

Deleuze seeks to undermine the idea of knowledge that is implied in the transcendental model of modern metaphysics, which, he argues, is a model and form of recognition (between self and world, or subject and object, and self and other). Construed in terms of a model or form of recognition, philosophy is unable to open itself up to that which exceeds its faculties and the norms it imposes on their operation (the aberrant, the anomalous, the fuzzy, the indiscernible, and so on).