The Evolution of Evolvability

Evolution remains a hotly debated subject because it is far from clear that scientists have yet explained, beyond all reasonable doubt, the process that has created the incredible variety of life on earth. A new life is created when some reproductive process produces a single copy of a genome. The secret of everything that follows is therefore contained within the genetic code of that single copy. How is it best to view this genetically controlled process? Derek Hough, in his theory of the self-developing genome (see below) suggests that it can help our understanding if we view the genome as consisting of two different hierarchies. He refers to one hierarchy as the operating system and he sees the other hierarchy as that part of the genetic program that puts together the individual building blocks for the creation of an organism. The essential difference between these two parts of the code is that the genes for creating the operating system have become common across millions of different species. Due to their success these genes have become fixed in the genomes of different species and they do not suffer from the same kind of competition as the genes responsible for building three-dimensional bodies. When a characteristic of life becomes partially or wholly universal further evolution will become less likely as far as that particular characteristic is concerned. The DNA code, for example, long ago won the battle between competing codes. It now has a virtual monopoly and because it seems to have proved to be the ultimate code that can’t easily be improved upon then any new code trying to compete with it is likely to be immediately eliminated. Other operating system characteristics that similarly seem to have become universal (or partially universal) are the structure of the cell, sexual and asexual reproduction and multicellularity. These characteristics work behind the scenes for the whole of life and not just for any individual species and they are not therefore subject to the same environmental scrutiny as the physical characteristics of an organism. Because of their universality these operating system characteristics are not eliminated along with bodybuilding genes when an organism is subject to natural selection. This phenomenon allows such operating system genes to overcome the strict adherence to the principal of selfish survival; competition is greatly reduced when a characteristic attains a degree of universality. Derek Hough’s theory recognises that an important characteristic of the operating system is a variety-maintaining mechanism, which he argues, is a natural consequence of the algorithmic process. (www.evolutionarytheory.co.uk) The arguments that point to the existence of such a mechanism are mathematical and can be demonstrated with the use of artificial computerized genetic algorithms. In other words, what evolution has created is a system of evolvability in which variety and complexity are continually being sought out. Or to put it another way evolution has evolved what we commonly understand to be the phenomenon of evolution, a system for the creation of different organisms.  The outpouring of new design or new variety provides the raw material on which Darwin’s natural selection can act. From simple beginnings, life’s genetic algorithm now creates variety from a large but essentially limited array of building blocks using an operating system that has hardly changed for possibly one billion years.

2009 Addendum

The year 2009 was a very important year for Evolutionary Theory. The subject was explored with great enthusiasm. Compared to previous Darwin anniversaries we are now in a better position to discuss the intricacies of evolution than ever before. Our knowledge of molecular biology has advanced beyond all recognition since even 1959. The first signs of discontent with neo-Darwinism amongst professional biologists are beginning to appear. On the 24^th January 2009, New Scientist magazine quotes Michael Rose from the University of California as saying ‘our whole fundamental view of biology needs to change.’ The following week Cambridge palaeontologist Simon Conway Morris talks about biologists needing an Einstein to explain the realities of evolution. But the greatest attack of them all seems to have gone largely unnoticed. In the final 15 minutes of an excellent BBC documentary entitled ‘What Darwin Didn’t Know’ the eminent biologist Armand Marie Leroi says ‘perhaps then, the war of nature is not simply a struggle among individuals or even genes but a struggle among different ways of organising life; a struggle between systems.’ He then says, ‘In the long run success needs flexibility, on being able to respond to a mutable and contingent world.’ And ‘In the short run, creatures evolve; in the long run they evolve evolvability.’ He posits that the first creature to evolve evolvability appeared perhaps 1 billion years ago. This creature was ‘an engine of innovation.’ Leroi is echoing Derek Hough’s theory more closely than any other professional biologist has ever previously dared. He has unwittingly opened a crack in the neo-Darwinian edifice into which the thin edge of the wedge can now be driven. See note (i)

This summary of the theory of the self-developing genome was rejected by Wikipedia

Self-developing genome

The theory of the self-developing genome is a systems-based solution to the problem of explaining the source of variety which acts as the raw material for natural selection. There is a three-fold requirement for any natural evolutionary process, namely, reproduction, variety and competition. According to the theory of the self-developing genome any natural system satisfying these requirements will evolve a mechanism of evolvability. The copying error, which is a cornerstone of neo-Darwinian theory, will evolve into a system of variety generation and variety maintenance at the level of the heritable sub-unit. The critical objection to this idea, emanating from the strict adherence to the principle of selfish survival, is overcome by recognising that many traits of life such as sexual reproduction (or gene exchange), cell structure, multi-cellularity and the genetic code itself are universal or partially universal characteristics and are not subject to the same environmental scrutiny as more manifest physical characteristics.

Underpinning the inevitable evolution of evolvability is the fact that the environment of every heritable unit (which is composed of all other heritable units) is never stable and this, coupled with the restrictions placed on design possibility by the limitations of physical and chemical possibility and the limitations of the DNA code, enable the system to ‘learn’ in an algorithmic sense something about this varying environment. Increasing complexity, whilst by no means necessary, can naturally evolve from this system due to the fact that heritable sub-units are linked together in a cooperating whole to form genomes. Increasing complexity can then emerge from the twin phenomena of variety-maintenance and cooperation which together can create genomes with novel combinations of sub-units. These unique combinations of sub-units can lead to the emergence of organisms of novel design which might find a suitable, available, vacant niche to which they are pre-adapted.

Note (i)

To illustrate the systems approach to evolutionary theory imagine a genetic system in which two extreme situations are theoretically possible. At one extreme we could envisage a situation in which every single organism is different due to the ubiquity of copying errors and at the other extreme we could envisage a situation in which every single organism is identical. Either of these two extremes could have been the starting situation for life on earth. When competition for survival is added to the already existing phenomenon of reproduction neither of these two extremes is stable. It can easily be demonstrated with computerised simulations that the first situation will tend towards improved copying fidelity and therefore fewer copying errors. The second situation is also unstable because sooner or later a copying error will result in the creation of an organism with superior survival skills and a variety of organisms and species will inevitably result. Neither extreme is stable and such a system will settle down somewhere between the two extremes. Because the eventual stable situation has been created by the system the mutations can no longer be described as copying errors but are now an integral part of a dynamic system.

For the more technically-minded, the computerised system for researching evolution should consist of not one genetic algorithm but a very large number of similar genetic algorithms all processing in parallel. Each genetic algorithm creates a sexually isolated species. The connection between these separate species is that each one has as its ‘environment’ the species created by all the other genetic algorithms. How best to achieve this would require a high degree of originality from the programmer. A fundamental principle of the self-developing genome is that there are not only genes that code for creating those physical characteristics of organisms which are vetted by the environment for fitness but also genes that work behind the scenes and which for example influence the output of reproduction. More specifically, the programmer must allow some genes to influence reproduction in order to maintain variety as a defence against an ever-varying and variable environment.