The theory of evolution is the overarching unifying theory in biology. Are there biological facts that the theory of evolution does not need to explain? Or does the theory of evolution have to explain every fact about life? According to the theory of evolution every species and every individual of a species is the result of evolution. That would imply that every feature of an organism must somehow be explained by the theory of evolution.
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| Aerodynamic forces on a bird (Videler, 2012) |
Even at the time when I was a student and attended evolutionary biology courses and did lab experiments on evolution, I had the vague idea that the theory of evolution was incomplete, although at the time I couldn't say why, or what exactly was missing (here). There is so much to explain, and "A change in gene frequencies over time" and "Differential reproduction of heritable variation" seem far too simple for the task. Yes, there was a Second and Third Evolutionary Synthesis, but still a lot was missing. Obviously, the planetary, geological and cosmological context of evolution is often missing in the textbooks. Last year I blogged about the fact that evolution textbooks are suffocating: very low levels of Oxygen! My list of top 20 evolution books (blog) reflects my preoccupation with the question of what is missing. Furthermore, physicist Rolie Barth pointed out physical factors and constraints in evolution (blog) [1]. At the other end of the spectrum: is evolution supposed to explain human behaviour, intelligence, consciousness, psychology, language, culture, civilization, war? What is the scope of the theory? Where does it end?
A few days ago I had an interesting discussion with google-AI about the question: Are there biological facts that the theory of evolution does not need to explain? The initial answers seemed incorrect and incomplete. So, I demanded better answers and google-AI came with surprisingly insightful answers:
- What evolution does NOT need to explain: The physics of how cells physically move, stick together, or split. For example, when a sheet of cells bends into a tube, it follows basic laws of fluid mechanics and surface tension.
- What evolution DOES need to explain: Why the cells bend into a tube at that exact moment, in that specific location, to form a spinal cord. The timing, the instructions, and the genetic switches that trigger those physical movements are entirely shaped by natural selection.
- What evolution does NOT explain: The electromagnetic forces that allow a hydrogen bond to form between Adenine and Thymine. That is pure physics and chemistry.
- What evolution DOES explain: Why a specific three-letter sequence (like UUU) maps to a specific amino acid (like Phenylalanine), and why this map is nearly universal across all life.
- Evolution does NOT explain: Why a hydrogen bond forms at all, why the universe is made of matter instead of antimatter, or the laws of thermodynamics that govern energy conversion.
- Evolution DOES explain: How life hijacked those inescapable physical realities and organized them into the intricate, Mendelian, metabolic, developmental masterpiece we call biology.
Additionally:
- Lipid Bilayers: Amphiphilic lipid molecules automatically assemble into complex, spherical, semi-permeable cell membranes when exposed to water, driven entirely by hydrophobic physical forces.
- Membraneless Organelles: Inside the cell, proteins and RNA's undergo liquid-liquid phase separation—similar to droplets of oil separating in water. This thermodynamic behaviour spontaneously forms highly organized, functional compartments (such as the nucleolus) without needing an explicit genetic blueprint directing every coordinate.
These examples can be expanded with:
Microtubules: the self-assembly of microtubules. The proteins themselves are inherited, but they self-assemble into microtubules.
Biochemistry: See also the primacy of biochemistry as opposed to genetic determinism [2].
Bio-electricity: "Without bioelectricity, your cells couldn't communicate, your muscles couldn't move, and your heart wouldn't beat." [3]:
- The Cellular Battery: Membrane Potential
- Nervous System Communication
- Muscle Contractions (Powering Movement and the Heart)
- Wound Healing and Tissue Regeneration
- Specialized Biological Superpowers (Electroreception, Electrogenesis)
Quantum effects: photosynthesis.
Mechanical forces: Venus flytrap [4].
Van der Waals forces that hold molecules together (Gecko).
Hydrogen bonds (DNA bases).
Aerodynamics (birds, bats, insects), hydrodynamics (fishes, dolphins, sharks, blood flow).
Gravity: Effect on body size (scaling laws).
Geomagnetic field: is used by pigeons for navigation
etc.
Read more...
Gert, you write: The theory of evolution is the overarching unifying theory in biology. Are there biological facts that the theory of evolution does not need to explain?
ReplyDeleteIndeed, a unifying theory in BIOLOGY, so this theory does not need to explain de laws of physics, the laws of pattern formation etc, but it needs to explain how biological processes can use these physical and chemical laws. And even more it should explain how biology is restricted by those physical and chemical laws (call it the fundamental constraints).
So, evolution does not need to explain hydroge bonds, Van der Waals forces, mechanical forces, etc. Evolution is exploring the abundance of physical and chemical possibilities within the fundamental constraints.
And you will agree with me that statement 4 is wrong.
What evolution DOES explain: Why a specific three-letter sequence (like UUU) maps to a specific amino acid (like Phenylalanine), and why this map is nearly universal across all life.
That is wishfull thinking. We have no evidence for the relation between codons and amino acids.
And, what I forgot to say: interesting that you explore these questions. What I said above can be summarised: biology doen not explain physics and chemistry, on the contrary these siences partly explain biological features.
ReplyDeleteThank you Rolie, good point!
ReplyDelete"What evolution DOES explain: Why a specific three-letter sequence (like UUU) maps to a specific amino acid (like Phenylalanine)..."
You're right, this is too optimistic, but Nick Lane has developed a rather detailed hypothetical scheme for the origin of at least a part of the genetic code:
A biophysical basis for the emergence of the genetic code in protocells,
So, we are not completely empty-handed!
Dear dr korthof
ReplyDeleteDoesn’t your diagnosis of the problem imply that biology is by definition incomplete? Darwin’s struggle with the evolution of language for instance in the Descent of Man may stand as an example, where he ended in calling it a human invention (on the same level as the invention of fire, btw). The first question about evolution, still is and was: evolution of *what*? - what is human language anyway. That’ s not a question biologists can answer- I’d say.
Note: I added Preliminary Conclusions to the blog.
ReplyDeleteDear dr. Anonymous, good point.
I think language can be dealt with changes in genes and gene regulators that control anatomy and function of the larynx and associated brain structures.
Consciousness is one of the two hardest problems of Evolution and Biology. However, brains are organs just as the lungs, and if consciousness is ultimately a property of the brain, and if consciousness increases fitness of the organism, than consciousness falls within the domain of The Theory of Evolution. Yes, we need specialists to solve the problem, but that doesn't mean the problem falls outside the domain of the Theory of Evolution. Can you live with that?
Dear dr korthof
ReplyDeleteAllow me a very first fast reaction to your last preliminary conclusion -,more to follow:
The hardest problem of all existing theories of evolution darwinian style ( eg new synthesis neo-darwinism, SET, EET, whatever, simply is: the origin of everything is a major problem- not just the origin of life, or consciousness. Survival ‘models’ can’t tell us anything about arrival whatsoever, because they just presuppose what they are trying to describe (model statistically , or just verbally in evolutionary ‘scenario’s , aka just so stories about some alleged ‘advantage's’ or ‘selection pressure(s)’ etc etc etc.
I added another reason to the Preliminary Conclusions why the Theory of Evolution is so compact.
ReplyDeleteDear Dr. Anonymous, you can and should do better than that in your latest comment. Give it another try.
Dear Dr Korthof
ReplyDeleteFunny you should add another reason to your list after my last post and before even answering it- your high level abstract paradigm gets abstracter and higher with each preliminary conclusion. Hard to keep up.
But we already knew, btw, that it does not predict 'the brute facts of life'. And I agree, we better leave all those details to e.g. CRISPR/CAS9 technology that allows not only for prediction of a lot of those brute facts of life, but turns the study of evolution into an experimental science.
Natural sciences, physics and chemistry, substantiate common descent and deep similarities of all life much more than any evolutionary model does.
We do’t need those trees, apart from all the controversies. To mention only one: the Failure of SRH (Stationary, Reversible, Homogeneous) Assumptions. Standard models assume that sites evolve independently and identically distributed (i.i.d.), an assumption that is completely out of the mark. See, for a quick update f.e. Ph. Ball’s "Why the Human Genome’s Tangled Physicality May Confound AI"- and not just AI models, for that matter.
If our brain is just an organ like our lungs, kidneys, liver, or whatever, then so far we could never have been emitting more than just a few air waves ('flatus vocis'), some quantity of urine or bile, or whatever. Anyway, not words, ideas, let alone preliminary conclusions.
Which reminds me of Darwin’s idea of language as a human “Invention”. You might like to read an almost overdue update here: The mystery of language evolution, featuring among others N. Chomsky and R. Lewontin, 2014:
“evolutionary analyses demand a clear specification of the target phenotype”.
Sounds much more than just another ‘preliminary conclusion’ to me. Even when talking about a ‘high level abstract paradigm’.
follow-up massage
Deletethis might interest you even more - after reading Ph. Ball's essay:
Jessica Sook Yuin Ho et al, Transposable element DNA and RNA: Drivers of gene expression, evolution, and disease
Cell. 2026 Jun 11;189(12):3513-3540. doi: 10.1016/j.cell.2026.05.003.
The article 'Transposable element DNA and RNA: Drivers of gene expression, evolution, and disease' is published in CELL, which is a top scientific journal. The article is a review of the literature about transposable elements. They claim there is a paradigm change or even a revolution necessary in genomics: from "a gene-centric landscape dotted with repetitive “junk” to mammalian DNA is a TE-rich ecosystem in which TEs drive gene regulatory networks and evolution".
ReplyDeleteIt is fashionable nowadays to attack junk DNA, and the authors solemnly declare the time of junk DNA is over. I don't have full access, but usually authors of those claims don't give a percentage of how much of the human genome is functional. The usual suggestion is that most of 'junk DNA' is useful or that it will be discovered in the future. The authors want to be at the forefront of that supposed revolution. They fail to see why their claims contradict populations genetics theory: natural selection cannot maintain a genome of 2x 3.2 billion base pairs. See: the book Laurence Moran (2023) 'What's in Your Genome? 90% of Your Genome Is Junk',
Friday you mentioned:
ReplyDeletePhilip Ball's
Why the Human Genome’s Tangled Physicality May Confound AI in Quanta magazine, a popular science magazine. Now, I admire Ball's beautifully illustrated book "The self-made tapestry. Pattern formation in nature", but in later books and articles he arrogantly and contemptuously criticised geneticists and biologists. I wrote several blogs about him. The only thing I agree is that DNA-centrism must be criticised. But, Ball hated DNA so much that he downplayed DNA, and the 1953 discovery of DNA and mentioned the Nobel Prize for Watson&Crick only in a footnote!!! So unimportant has DNA become for Ball! It's clear from this that Ball cannot inform us in a balanced way about developments in genetics and genomics. You cannot have a useful discussion with biologists if you write as if they are stupid morons.
dear Dr Korthof
ReplyDeleteTE research is just another example of fast burgeoning experimental evolution research that, thanks to new sequencing techniques like T2T, among other things, renders ‘tree’ models obsolete. Just like discussions about percentages, and for that matter regardless of whether you call this research fashionable or not.
A recent example free access example you will find in: Cell Genomics Volume 5, Issue 10100979October 08, 2025
Apart from regulating stem cells, jumping genes are also driving human complexity, controlling neural growth and above all creating mental diversity: they can shift locations in individual neural progenitor cells, creating a mosaic of slightly different genomes within a single brain, which may explain the immense diversity in human behaviour, emotions, and unique ways of thinking.
Also, dysfunctional TEs drive conditions like Alzheimer's disease, Parkinson's disease, and major depressive disorder.
I’d say this kind of neuroscience research is one vindication of the work of Barbara McClintock -that still seems hard to digest in some circles.
Whatever the authors fail to see about ‘natural selection’, any nitpicking about percentages is irrelevant here—I believe even Moran admits that.
Ball could be criticised on his take on present AI. Of course, ‘a computational black box will never suffice’. Hype or not, right now AI tech is growing exponentially and will be able to “worry about the complicated regulatory stuff going on” working with vast quantities of (new) genomic data", e.g. https://doi.org/10.1016/j.cell.2026.03.044 without this “straightforward input-output approach”.
Even though the problem of the ‘computational BB’ won’t be solved any time soon, it will eventually become clear to everyone whether biologists can indeed be called morons as some critics seem to do.
Anyway, either way, it makes it very hard to think of brains as just another organ like any next organ - if not just impossible.
Sounds much more than just another ‘preliminary conclusion’ to me. Even when talking about your ‘high level abstract paradigm’.
Two remarks about Transposable DNA elements.
ReplyDelete1. DNA transposons do not transpose themselves, they are (passively) being transposed to another location on the chromosome by the enzym Transposase. Again we see here that DNA is a passive molecule, and the cell (enzymes) is the active one.
2. RNA interference (RNAi) is a vital part of the immune response to viruses and other foreign genetic material, especially in plants where it may also prevent the self-propagation of transposons. So, organisms have evolved defenses against transpositions. That means they usually are deleterious, mostly neutral or rarely beneficial. Just as any other mutation. I wrote about RNAi 10 years ago: Ronald Plasterk: RNAi is het afweersysteem tegen Selfish DNA (transposons) 17 Feb 2016 (Dutch).
dear dr Korthof
ReplyDeleteThat *transposons do not transpose themselves*, and are indeed *usually deleterious, mostly neutral or rarely beneficial*, is not at all up for discussion here.
Also, none of researchers I mentioned have claimed the opposite, as far as I know.
I'd say their results not only vindicate B. McClintock’work, but also support S. Brenners - and your own- cell-centered 'dogma'.
So, I only take note of your remarks and look forward to your response on my other comments.