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Ultra-Conserved Elements: New Paper, Same Old Results

Photo credit: Stian Martinsen, CC BY-SA 4.0 , via Wikimedia Commons.

The theory of evolution would absolutely be falsified if conserved structures that are not functionally constrained were discovered. That, at least, is what my friend Steve (not his real name) explained to me twenty years ago. Steve, an evolutionist and life science professor, was responding to the problem that evolution seems to be unfalsifiable. No matter how many of its predictions turn out to be false, the theory remains unharmed. When a failed prediction is ignored like this, it means it never really was a prediction to begin with. At least not a hard prediction. If the prediction turns out to be false, then the theory can easily be adjusted. The prediction might be true, it might be false — it doesn’t really matter because it was a soft prediction.

Now there is nothing wrong with soft predictions, per se. But what if all the predictions of a theory are soft? Then, in spite of what you learned in high school, the science in this case is not testable or falsifiable.

One of Those Theories

The problem is evolution seems to be one of those theories. Perhaps that is inevitable with high-level theories of origin. In fact, philosopher of science Imre Lakatos recognized the possibility of unfalsifiability in science. For Lakatos, scientific research programs could be characterized by their “hard core” beliefs which are surrounded by a protective belt of auxiliary hypotheses:

It is this protective belt of auxiliary hypotheses which has to bear the brunt of tests and get adjusted and re-adjusted, or even completely replaced, to defend the thus-hardened core.1

Lakatos may have been on to something, but his model of science hardly comports with our modern view of a testable, objective, empirically driven thing called science. How many evolutionists would agree (or admit) to having “hard core” commitments that are protected at all costs from empirical evidence? Certainly not my evolutionist friend Steve.

Steve was certain that evolutionary theory was perfectly falsifiable. All that one would need to find are conserved structures that are not functionally constrained. That, according to Steve, was a hard prediction of evolution. But what exactly does this prediction mean, and why is it important?

This prediction that conserved structures must be functionally constrained means that if you find the same type of structure (such as a gene or internal organ) across different related species, then that structure must be inherited by common descent, and it must have some importance to the organism. The structure must have utility, and it cannot be arbitrarily modified or removed without affecting the organism’s reproductive advantage. That is to say, such structures are functionally constrained.

So There You Have It

According to Steve a hard prediction of evolution is that conserved structures are functionally constrained. Any finding of conserved structures that are not functionally constrained would absolutely falsify the theory, once and for all. This prediction, according to Steve, is not soft.

Before I explain how this prediction has fared, I need to explain why it is important. For Steve’s proposal is a core concept, and a core distinction between intelligent design and evolution or, more generally, between teleology and anti-teleology.

Going at least as far back as Epicurus and his followers in antiquity, anti-teleology has always been linked with immediate utility. Teeth are not for chewing, but rather teeth exist because they happened to be useful for chewing. This view was inherent in Darwin’s key concept of natural selection. Selection works only on structures that contribute to the current fitness of the organism. They must have some utility, and specifically utility leading to immediate improved reproduction. If the improvement comes in some future era when conditions have changed, then evolution is powerless to select the structure.

Intelligent design and the teleological view, on the other hand, do not require such immediate utility, or even any utility at all for that matter. A tire repair kit may be included and conserved across all the automobile models from a given manufacturer, but it does not have utility except in rare, future, events of a flat tire.

Teleology Versus Anti-Teleology

In his proposal for a hard prediction of evolution, Steve was, in fact, getting at an important, fundamental concept that distinguishes teleology from anti-teleology.

But this prediction has disproven anti-teleology many times over. It never was a hard prediction of evolution or anti-teleology, but rather a failed fundamental tenet. Consider, for example, the so-called ultra-conserved elements (UCEs). Discovered about 15 years ago (not long after Steve issued his “hard” prediction), UCEs are long stretches of DNA that are not merely similar, but in fact identical, or nearly identical, across different species. They also are often not functionally constrained. In a battery of on-going tests, UCEs have been mutated and altogether deleted, often with little or no perceptible impact on the organism’s fitness. As a recent review article concluded:

Currently, unanswered questions remain about why ultraconserved sequences are so highly conserved and exactly what function evolutionary selection is acting on to maintain this conservation. To date, half of all ultraconserved enhancers deleted in mice have not been shown to result in a potentially detrimental phenotype, and there has been no direct demonstration that loss of any ultraconserved enhancer results in reduced viability, fertility or fecundity.2

UCEs are conserved structures that are not functionally constrained. Yet there is not so much as a hint of a problem for evolutionary theory. As the review explains, they simply must continue to search for more UCE utility. You see this never was a hard prediction of evolution or anti-teleology in the first place. It joins the long list of failed evolutionary predictions that have, instead, confirmed nature’s teleology.

Oh, and Steve is still an evolutionist.


  1. Lakatos, Imre. 1970. “Falsification and the Methodology of Scientific Research Programmes.” In I. Lakatos, A. Musgrave eds., Criticism and the Growth of Knowledge: Proceedings of the International Colloquium in the Philosophy of Science, London, 1965 (pp. 91-196). Cambridge: Cambridge University Press. p. 191.
  2. Snetkova V, Pennacchio LA, Visel A, Dickel DE. Perfect and imperfect views of ultraconserved sequences. Nat Rev Genet. 2021 Nov 11. doi: 10.1038/s41576-021-00424-x. Epub ahead of print. PMID: 34764456.