New Concepts in the Evolution of Complexity: Stratified Stability and Unbounded Plans

New Concepts in the Evolution of Complexity: Stratified Stability and Unbounded Plans I. INTRODUCTION Vitalism is a traditional and persistent belief that the laws of physics that hold in the inanimate world will not suffice to explain the phenomena of life. Of course it is not suggested, either by those who share the belief or by those like me who reject it, that we know all the laws of physics now, or will know them soon. Rather what is silently supposed by both sides is that we know what kind of laws physics is made up of and will continue to discover in inanimate matter; and although that is a vague description to serve as a premise, it is what inspires vitalists to claim (and their opponents to deny) that some phenomena of life cannot be explained by laws of this kind. The phenomena that are said to be inaccessible to physics are of two different kinds. One school of vitalists stresses the complexity of the individual organism. The other school of vitalists asserts that physical laws are insufficient to explain the direction of evolution in time: that is, the increasein complexityin newspecies,such as man,when compared to old species from which they derive, such as the tree-shrews. The two grounds for finding physics to fall short are therefore quite distinct, and I shall discuss them separately. I begin with a summary sketch of each. The first ground, then, is that the individual organism (even a single cell) functions in a way which transcends what physics can explain, and implies the existence of laws of another kind-what Walter Elsasser calls “biotonic laws”. Elsasser argues that the development of an organism is too complexto be coded in the genes, and that there must be larger laws of biological organization that guide it overall. Eugene Wigner argues that development and reproduction are subject to so many statistical variations that there can be no certainty that the organism will survive them unless it is controlled by higher laws. These arguments do not differ in principle from the classical argument, put From J. Bronowski. A Sense otthe Future. @ 1911 Massachusetts Institute of Technology. published by the MIT Press, Cambridge, MA, U.S.A. Reprinted by permission. - . Jacob Bronowski forward (for example) by Bolingbroke early in the 18th century, that an organism is at least as complicated as a clock, and that we cannot imagine a clock to have come into being by accident. True, neither Elsasser nor Wigner speaks of origins, but both imply that the configuration of parts and the sequence of functions in the cell require a higher coordination than is provided by the laws of physics-by what one might call the simple engineering rules between the parts of the clock. Bolingbroke ascribes this higher coordination to God, and Elsasser and Wigner to biotonic laws, but this is only a difference in nomenclature. The second school of vitalists finds anotherground for claiming that the laws of physics are biologically incomplete, namely in questions about the evolution of organisms. Michael Polanyi asks questions of this kind, though he lumps all levels together-origins, functioning of individuals, and the sequence of species. He claims. as vitalists have alwaysdone, that there must be an overall plan which directs them all, and I shall criticize the confusion of meanings in his idea of plan or purpose. I shall distinguish between two concepts, the usual concept of a closed or bounded plan (that is. a tactic or solution for a defined problem), and a new concept of an open or unbounded plan, that is, a general strategy. But beyond these concepts, there remains the crucial question raised by Polanyi-and others before him. of course, in earlier forms. Evolution has the direction, speaking roughly, from simple to more and more complex: more and more complex functions of higher organisms, mediated by more and more complex structures, which are themselves made of more and more complex molecules. How has this come about‘? How can it be explained if there is no overall plan to create more compiex creatures -which means, at least,if there is no overall law (other than evolution as a mechanism...