Question

What does ‘Evolution behaves like a tinkerer’ by Francois Jacob mean?

Answer 1

François Jacob discoverer of lac operon enzyme regulation model in bacteria awarded Nobel prize in 1965. Based on his experience with gene regulation models and the tinkering chemistry he worked with published an essay in Science (1977) “Evolution and Tinkering,". He says that a mutual similarity between the course of evolution by natural selection and the methods of engineering is not comparable. He says that the process of evolution happened by eclectic construction by tinkering around. In this essay, He does not refute the importance of the mechanism of natural selection in shaping complex adaptations. Instead, he maintains that the cumulative effects of history on the evolution of life, made evident by molecular data, provides an alternative account of the patterns depicting the history of life on earth. Jacob's essay contributed to genetic research in the late twentieth century that emphasized certain types of topics in evolutionary and developmental biology, such as genetic regulation, gene duplication events, and the genetic program of embryonic development. It also proposed why, in future research, biologists should expect to discover an underlying similarity in the molecular structure of genomes, and that they should expect to find many imperfections in evolutionary history despite the influence of natural selection.

Here we will summarise and discuss main themes in his seven page publication.

In science to explain something or to have a valued opinion, the investigator should have knowledge of or worked with that, and he is able to predict the outcome. Science can progress by revealing a previously unnoticed facet and this is possible if we have a different look or observation. Nature functions by incorporation of objects at different levels and selects organizations, or systems. At each level, new properties may appear which enforce new limitations on the system. But as a general rule, the statements of greatest importance at one level are of no interest at the more complex ones. Complex objects are produced by evolutionary processes in which two factors are paramount: the constraints that at every level control the systems involved, and the historical circumstances that control the actual interactions between the systems. The combination of constraints and history exists at every level, although in different proportions.

Natural selection is the result of two constraints imposed on every living organism: 1. the requirement for reproduction, which is fulfilled through genetic mechanisms carefully adjusted by special devices such as mutation, recombination, and sex to produce organisms similar, but not identical, to their parents, and 2. the requirement for a permanent interaction with the environment because living beings are what thermodynamics call open systems and persist only by a constant flux of matter, energy, and information. Natural selection has no analogy with any aspect of human behavior. However, if one wanted to play with a comparison, one would have to say that natural selection does not work as an engineer works. It works like a tinkerer - a tinkerer who does not know exactly what he is going to produce but uses whatever he finds around him. In short he works like a tinkerer who uses everything at his disposal to produce some kind of workable object.

The tinkerer always manages with odds and ends. What he ultimately produces is generally related to no special project, and it results from a series of contingent events, of all the opportunities he had to enrich his stock with leftovers. As was discussed by Levi-Strauss, none of the materials at the tinkerer's disposal has a precise and definite function. Each can be used in a number of different ways. In contrast with the Engineer's tools, those of the tinkerer cannot be defined by a project. Often, without any well-defined long-term project, the tinkerer gives his materials unexpected functions to produce a new object. Evolution behaves like a tinkerer who, during eons upon eons, would slowly modify his work, unceasingly retouching it, cutting here, lengthening there, and seizing the opportunities to adapt it progressively to its new use. Evolution does not produce novelties from scratch. It works on what already exists; either transforming a system to give it new functions or combining several systems to produce a more elaborate one. Small changes modifying the distribution in time and space of the same structures are sufficient to affect deeply the form, the functioning, and the behaviour of the final product - the adult animal. It is always a matter of using the same elements, of adjusting them, of altering here or there, of arranging various combinations to produce new objects of increasing complexity. It is always a matter of tinkering.

Sex is one of the most efficient inventions of evolution. An evolutionary biologist, Simpson pointed out; the interplay of local opportunities - physical, ecological, and constitutional -produces a net historical opportunity which in turn determines how generic opportunities will be exploited. It is this net historical opportunity that mainly controls the direction and pace of adaptive evolution.

You may read his publication in this link

https://pdfs.semanticscholar.org/e806/647ac8f0ccc546934de20d536f14a2719738.pdf