To most people the name Louis Pasteur is associated with vaccination or pasteurization. Much less well known is the role he played in the demise of belief in the spontaneous generation of life. Even less well known is the fact that the controversy surrounding spontaneous generation with Pasteur at the center involved philosophical/theological disagreements that have interesting parallels to contemporary debates over creation/evolution.
Spontaneous generation is the belief that life can appear suddenly from non-living matter without the benefit of parents or any previously existing life. In the middle of the nineteenth century there was already a variegated history with proponents and opponents on both ends of the theological spectrum. For a long time, from St. Augustine forward, it had enjoyed the support of Christian theologians, but by Pasteur’s era in the 1850’s, belief in spontaneous generation was largely associated with materialism and other anti-religious, even atheistic philosophies. This was particularly true in Pasteur’s France where it was also connected with ‘transformism,’ the belief that species could change into other species in a linear fashion over time, a theory developed by the Frenchman Lamarck at the beginning of the nineteenth century. Transformism and spontaneous generation were lumped together as being antithetical to the commonly accepted belief in special creation held by the vast majority in Catholic France.
Pasteur began his career as a chemist and crystallographer. His interest in the biological question of spontaneous generation arose through his investigation of fermentation. He had come to the conclusion that fermentation arose as a consequence of the presence of microorganisms, not the other way around. Hence he was skeptical when a prominent French biologist named Felix Pouchet in 1858 sent a paper to the French Academie des sciences in which he claimed to offer experimental proof of spontaneous generation. Specifically, Pouchet reported the appearance of microorganisms in boiled hay infusions under mercury after exposure to artificially produced oxygen, thereby claiming that germs in atmospheric air were not necessary to engender life in previously boiled liquids. Pasteur began a polite private correspondence with Pouchet in which he suggested that Pouchet had unwittingly introduced contaminated air. The controversy was significantly heightened in 1859 when Pouchet published a major work entitled “Heterogenesis: A Treatise on Spontaneous Generation” in which he set forth both his philosophical/theological and scientific rationale for his belief in spontaneous generation. We are more interested in the theological components, but before we discuss those we need to finish the scientific story.
The publications by Pouchet reenergized the controversy over spontaneous generation and led to the announcement that the Academie des sciences’ Alhumbert prize in natural science in 1862 would be awarded on the topic: “To attempt by means of well-designed experiments to cast new light on the question of the so-called spontaneous generations.” To this point Pasteur had engaged in only an incidental fashion in any research directly related to the spontaneous generation question, but spurred by the rising controversy and with the incentive of the prize he initiated an intensive research effort on the question. By an ingenious set of carefully designed experiments involving ‘swan-necked’ flasks as well as experiments carried out at different elevations around Europe, he demonstrated that in the absence of dust particles from the air, microorganisms did not appear in previously boiled organic matter. He submitted a paper to the Academy des sciences reporting his investigations entitled “On the Organized Corpuscles That Exist in the Atmosphere” in which he reported his results that countered the claims of spontaneous generation and in which he disputed the validity of Pouchet’s work, attributing the contamination of the hay to dust particles floating on the mercury. Pouchet initially had submitted a paper in the competition, but withdrew, suspecting that the committee responsible for the decision had already made up its mind. Pasteur’s paper turned out to be the only submission, and he was awarded the prize of 2500 francs.
The victory of Pasteur in this prestigious competition did not herald the final ascension of the anti-spontaneous generation forces. In fact, strictly speaking, Pasteur’s victory over Pouchet led to the demise of only one facet of spontaneous generation, what Pouchet had termed heterogenesis. Pouchet held to the belief that life could spontaneously arise from organic matter. The belief that life can arise from non-living inorganic matter, what is generally referred to as abiogenesis, continued as a viable alternative and remains thus more than a century later, although in modern origin of life theory it is viewed as a gradual rather than a spontaneous process. Thus, one could argue that Pouchet’s science, according to the current modern view, was partially correct. His belief that non-living matter could give rise to living matter squares with the current viewpoint in origin of life science, though both his limitation of the process to organic matter and his belief in a rapid and currently observable process would be called into question today.
Join us tomorrow as we continue this post into a discussion of the theological implications of the spontaneous generation controversy.