From Fitness to Optimality: The Back Swing of Darwinism's Clock
This year is the 200th anniversary of Darwin’s birth and the 150th anniversary of the publication of The Origin of Species.
Looking back at the developmental history of biological thinking over the 150 years since the publication of The Origin of Species, we noticed that the pendulum of Darwinian clock has meaningfully swung back. In a recent published preliminary report The Development of the Neo-adaptationist Biology, written by Brain & Ecology Comparative Group (BECG), this phenomenon and its significance were analyzed on the background of biological history.
The report mentioned that Darwin in his book did not define and use the concept "adaptation". But in the discourse he repeatedly used a comparative term, the "fittest". This shows that, in Darwin's thinking, adaptation is more appropriate as a relative or referenced standard. This is the original point of the "Darwinian clock". Half a century later, based on Darwinian “fittest” idea, the Modern Synthesis proposed that using “reproduction” to measure different organisms’ adaptation levels, in order to solve the issues in quantitative analysis of adaptation. Thus they created the measurable concept “fitness”. This change marked the focus of evolutionary biology was shifted from phenotypic comparison of Darwin’s times into genotype’s comparison of the modern era, marking the "Darwinian clock" pendulum has swung away from the original point.
This in essence turns from the phenotype determinism to the gene determinism. It has a historical background that due to there is a substantially fuzziness in evolutionism on the micro-process of organisms’ variation, the Modern Synthesis on the basis of genetics introduced the genetic variation theory to give a micro-empirical support for the natural selection model in explaining the causes of adaptation, and this revived the once depressed evolutionism to become a basic tool of biology with extensive explanation power. Therefore, as a theoretical result of the micro-biology times, the Modern Synthesis naturally replaced the original position of the traditional evolutionism. Moreover by abandoning phenotype, the "fitness" concept showed the self-confidence of the "genetic determinism" theory.
Particularly, the report explained why the prosperity of the Modern Synthesis had remained for 80 years. The cause is that the genetic determinism implies a tacit principle: as long as the mutation of gene was able to be passed to future generations, the predevelopmental primordial germ cells of the offspring may be automatically led by its own developmental mechanics and phenotypically express the mutated gene. However, the disproportionate suppression of population dispersal by natural selection does not directly target at gene, but targets at gene’s carrier (phenotype). And it is not a selection aiming at one trait of the phenotype, but a holistic selection aiming at the phenotype carrier.
This latent principle is the most fatal flaw of the Modern Synthesis. Therefore, the in-depth problem emerges. Why is this phenotype being selected rather than that one? How is the physio-ecological process proceeding when a phenotype is selected in a concrete environment? Thus, the issue of adaptation comes back from gene to phenotype again, and returns to the traditional question: how each phenotype was selected in its life-history under different natural conditions? The Modern Synthesis encounters an insurmountable barrier in theoretical explanation.
In the report, BECG focused on the development of intraspecific comparative biology, put forward the neo-adaptationist analysis of phenotypic “optimality”, and created a new comparative idea: adaptation is phenotype-centered, and it refers to organism’s morphological structures and physiological functions etc. presenting optimality in using environmental resources and resisting environmental stress under specific ecological niche. This analysis can be use to measure organisms’ adaptation level. Comparing with Modern Synthesis’s “fitness”, "optimality" concept inherits the Darwin's original idea "fittest", how degagely the pendulum of "Darwinian clock" swings back to the original position 150 years later.
The report suggest that the biotic adaptation ology is only a half-done and rough theoretical framework, and the evolutionism has just succeeded in creating an adaptation theory at the ecology level, but the physiology-leveled ology remains to be formed. Therefore the intraspecific adaptation biology shows its historical significance, it has a distinct emphasis on the physiology-leveled adaptation. On the one hand, it inherits the historical tradition of adaptation comparative study. The other hand, it entirely enters into micro-physiological process. Thereby neo-adaptationism is the another new synthesis following the evolutionism and the Modern Synthesis. 【BECG】