Evolutionary thinking (due to Darwin) is no doubt one of those paradigm shifting moments in scientific history, changing how we conceive of the world around us and ourselves. The idea of ‘Descent through Modification’ is now well established and accepted.
While evolution is not a disputable fact, a major source of debate a few decades ago (and even nowadays, to some extent) has been the causes for evolution. Enter a evolutionary biology class and you will see that everyone tries to explain observable traits (non-jargon way of saying phenotypes) using fitness arguments – how this or that trait was required for survival and reproductive success, and hence it is here today. These arguments stem from a view that is called the ‘Modern Synthesis’ – evolution happens primarily through natural selection, and natural selection requires a set of variants to select from, and this variation within a population is given by random genetic mutation. It is called the ‘Synthesis’ since it combined ideas from evolution and genetics to give a plausible answer to the mechanism of evolution. The whole idea of evolutionary game theory rests on this hypothesis, and so does evolutionary psychology.
However, a physicist or a mathematician or anyone else who tries to look for patterns in phenomena will tend to be exasperated by natural selection arguments for everything: in some cases, it is obvious that natural selection caused evolution, while it is not so in others. However, a knee-jerk answer to any evolutionary question by a biologist will invoke natural selection. Now, most of these answers are plausible, but that does not mean anything. For example, a crash in a predator population can easily be put down to a lack in fitness, but everyone who has studied the predator prey model will tell you that this crash comes about due to interactions between predator and prey populations, and has nothing to do with genes or natural selection.
Creating evolutionary fairy tales frees the biologist from looking at a phenomena at a deeper level, and sometimes one feels that depth is what is lacking when one reads up evolutionary biology. The oft quoted example is of the Fibonacci spirals in plants – this shows up everywhere, from shapes of galaxies to arrangement of seeds in flowers. A hardliner selectionist would tell you that this is because there were many variants of the universe and ours was the only one that managed to survive (reproduce?), and thus all such successful survivors will have Fibonacci spirals because of their ‘fitness improvement’. Now, one cannot disprove this, no doubt, but the question is whether one should accept it.
For me atleast, the answer is no – while selection of variants has its place in biology and (I sceptically say this) in other fields, it cannot explain the unity underlying phenomena: Certain things ‘just happen’ to look/behave/think similarly, and this evolution via selection cannot explain. Are there physical, chemical, informational constraints on a living being that simply does not allow certain variants? Are ‘gaps in the fossil record’ actually ‘gaps’ – is there a step jump from one form to another? Answering these questions is way harder than coming up with ‘plausible’ selectionist arguments, and has very rarely been attempted in the history of biology. However, if evolutionary theory has to have the depth seen in physics or mathematics, such work has to inevitably happen.