Controlling Life: Jacques Loeb and the Engineering Ideal in Biology
The history of biology is the history of struggles over the difference between the animate and the inanimate. Natural philosophy, through the Renaissance, and folk wisdom for a much longer time, saw the entire natural world as a single interconnected system in which radical transformations of qualities of both living and nonliving things were entirely credible. It was not merely that one inanimate kind of substance could, by alchemical transformation, be made into another, or that a vain boy could become a flower, but that the inanimate and the animate were interchangeable. Men could be petrified and marble statues turned to warm flesh in the embrace of their admirers. Papal staves put forth leaves, while moldy cheese and rags bred forth mice.
Aristotle believed animals could come from mud and that the animate and inanimate graded imperceptibly into one another on the scala naturae. But even the ancients were ambivalent about the ease with which inanimate matter could make that imperceptible transition. Despite Lucretius’ assurance that “even today many animals spring from the earth, formed from the sun’s heat and rain,” it was not regarded as an everyday occurrence. In the Metamorphoses, Ovid gives few examples like the case of Pygmalion’s statue and the creation of man from clay by Prometheus.
The raising of the dead by Jesus was, after all, the evidence of special powers and the leafing out of the Pope’s staff a sign of special grace. Moreover, the transition from Aristotle’s view to our present belief that the living are separated from the dead by a one-way bridge was a long and problematical one. Already in the seventeenth century William Harvey had declared ex ovo omnia, but the idea of spontaneous generation—that life originated from nonliving matter—was given a boost when Leeuwenhoek, looking through his microscope, saw a multitude of tiny living particles swimming by.
The Whig history of science we learn in school tells us that by the end of the eighteenth century Spallanzani had nailed down the case against spontaneous generation by his experimental approach to what was purely metaphysical speculation by wicked Aristotelians. But, as a matter of fact, the very same experiments done by others got the opposite result, supporting spontaneous generation. The disproofs of spontaneous generation that we now regard as definitive, those of Pasteur showing that microorganisms reproduce, were carried out in response to a public solicitation by the French Academy of Sciences for someone to finally settle the issue—in 1860.
We should not imagine, like the Whig historians of science, that the struggle over spontaneous generation was a story of the triumph of materialism and empiricism over superstition and a priori natural philosophy. On the contrary, nineteenth-century materialists took sides against the biogenetic law, the rule of “all life from life.” For if there were an unbridgeable gap between the nonliving and the living, how could we explain the primal origin of life except by the infusion of a vital spirit into clay …