Even Scientists Seem Unable to Change Their Minds

These are times that shake our trust in human rationality. The current reactions to the scientific consensus regarding climate change or the great benefits of vaccination display worrying (and highly dangerous) resistance to facts that conflict with pre-existing world views. In these cases, there is a silver lining to be found in the observation that there is real consensus and that scientists (except for a few cranks and notorious contrarians) are able to “stick to the facts”. But any comfort I get from viewing the scientific domain as an island of sanity amidst an ocean of madness is eroding as well. Let me explain. One of the benefits of being a scientist at my career stage is having the time to think about and, at times, review the more sweeping ideas in one's area of major interest. In my case, that means biological evolution. Evolution can, at a deep level, be seen as a highly intricate interaction between chance and selection, leading to differential survival over generations. You might say that this description is so broad as to become almost meaningless, but it serves the purpose of clarifying why it is so easy to have wildly differing ideas about certain events occurring during the evolution of life (and of course during the origin of life itself). What counts as real chance or selection and what are the shifting relative contributions in major evolutionary transitions such as the origins of life, eukaryotes, the nucleus, or meiotic sex, to name but a few examples? Because these are highly complex questions about events that happened eons ago, a lot of speculation cannot be avoided. This entails widely differing opinions about all these instances of momentous evolutionary change. It does not mean that it is all just speculation, and in every example I mentioned, new findings have, in principle, narrowed down the available explanations. Alas, the qualifying “in principle” tells a discomforting story. Do we see researchers discarding theories in the light of new evidence? That depends on how invested they are in the theory at hand. It turns out that scientists almost never change their minds either: they stick to their favorite models no matter what. Let me first try to take away a sneaky suspicion the reader might now entertain, that I am complaining about some of my own pet theories not being widely accepted. Surely there will be some of that, but I can see such inflexibility objectively in numerous instances where I have no skin in the game at all. So, did I ever change my mind myself? In 2011, I published a paper stating that so-called constructive neutral evolution (CNE; see [1]) had “major conceptual problems” [2]. In essence, the discussion is precisely about the balance between chance and selection. CNE argues that, under the appropriate circumstances, chance processes can allow ongoing neutral or even slightly deleterious changes to bring about complex, but “useless”, phenomena, such as kinetoplastid RNA editing. Though my article still seems helpful when it comes to thinking about how unexpected selective forces might enter the picture, I now think that CNE is basically correct. So, what changed? Here, considerations from population dynamics come in. The “useless” phenomena CNE tries to explain all occur in eukaryotes, which are characterized by (much) smaller population sizes than prokaryotes. Models show that small population sizes, weakening selection, shift the balance in favor of chance [3]. I would love to claim to be more open-minded than the average scientist, but I sincerely doubt it. In the end, two factors seemed to explain my “conversion”: active contact with proponents of the alternative theory and time. We are always taught that a major part of scientific education consists of learning to overcome our biologically hard-wired resistance to new, conflicting ideas [4]. To be honest, I have come to think that, at best, scientists are only marginally more open to ideas that challenge their preconceptions than non-scientists. How can we cultivate more flexible thinking in science and society? Part of the answer to that important question: creating societies with a constant open flow of ideas in which experts can be trusted. Such trust has to be earned by trying even harder to practice what we preach: open-mindedness. There are no conflicts of interest to report.