Here, I will examine two developments that are causing a rethink about natural selection, particularly relevant to one of its iconic standards, the peppered moth myth (hence peppered myth). The peppered myth was one of ten classic stories about evolution critiqued in detail by our late friend and ID leader Jonathan Wells in his 2000 book Icons of Evolution. His arguments remain as solid as ever: peppered moths do not rest on tree trunks (the famous photos were staged), and the population numbers of dark and light varieties of Biston betularia (a single species! — no origin of species occurred!) were never linked to predation by birds. In Zombie Science (2017), Dr Wells updated the peppered myth showing that a more recent study by Majerus could not resurrect the classic icon. The peppered myth “is not empirical science, but zombie science,” he said, yet it still lurks in textbooks and school classrooms with the other icons of evolution that refuse to die.

I wish Dr. Wells could have read this week’s article about industrial melanism in Current Biology. He would have been motivated to contribute some additional paragraphs about the peppered myth. Scientists are learning that melanism is not a function of genetic mutations at all. What switches on the dark and light colorations in these moths and in many other animals are RNAs — long noncoding RNAs (lncRNA) and microRNAs — in highly regulated processes that appear responsive to the environment. That is not our grandparents’ understanding of natural selection.

The Nobel News

First, the importance of non-coding RNAs, previously dismissed as transcripts of junk DNA, skyrocketed this month when two biologists were awarded the 2024 Nobel Prize for their discovery of microRNAs. Michael Le Page reported in New Scientist:

The 2024 Nobel prize in physiology or medicine has been awarded to Victor Ambros and Gary Ruvkun for the discovery of tiny pieces of RNA, called microRNAs, that play a key role in regulating gene activity in animals and plants.

The reason they are important is that a single microRNA can control many different genes. A single gene can also be regulated by multiple microRNAs. [Emphasis added.]

MicroRNAs are short pieces of RNA about 20 base pairs long, often folded into a hairpin shape. Ambros and Ruvkun discovered one in the 1990s, and another in 2000. Now, many thousands are known and understood to act as switches. The Scientist notes that the second microRNA they found is “evolutionarily conserved, found not only in sea sponges and worms, but importantly, also in mice and humans.” One can drop the word “evolutionarily” from “conserved” because there was no evolution. Emily Cooke at Live Science says that two decades after this first discovery, “these molecules are now lauded as essential governors of cell development and function.” The BBC News tries to rescue Darwinism by claiming that “microRNAs helped enable the evolution of complex life forms,” but the context shows instead that miRNAs are responsible for differentiating cell types from the same genome in the body. That is not a random process, nor is it evolution!

Important for design advocates, microRNAs also appear responsive to the environment. Eleven authors of a 2015 paper in Frontiers in Plant Science explain what they found:

New Arabidopsis microRNAs responsive to abiotic stresses were discovered. Four microRNAs: miR319a/b, miR319b.2, and miR400 have been found to be responsive to several abiotic stresses and thus can be regarded as general stress-responsive microRNA species.

Their article was one of six papers on the research topic, “MicroRNAs and their role in plant nutrient stress response.” What they found in Arabidopsis is likely a general rule in both plants and animals. MicroRNAs regulate cellular activity by switching gene transcripts on and off in response to environmental cues. 

Environmental responsiveness fits well with hypotheses being tested by attendees at CELS conferences. They propose that internal sensors and switches in organisms produce variations by design and foresight rather than by random mutations and natural selection. Without such systems already in place, organisms would be at the mercy of genetic damage waiting for improbable “beneficial mutations” to arise by chance. Or worse, they could never last long enough for coordinated mutations to improve complex systems. Dr. Richard Sternberg has shown that the waiting time for just two coordinated mutations (out of tens of thousands needed) in the path from land animal to whale would vastly exceed the time available. 

And yet variations in organisms are observed: scale patterns in Lepidoptera, fur colors in mammals, seasonal changes in reproductive activity. The discovery of microRNA switching networks opens new windows of research to understand how organisms can adapt quickly to signals from the environment without waiting for lucky mutations to occur. With this Nobel Prize-winning understanding of molecular switches, we can look at the topic of peppered moths with sharper lenses.

The Peppered Myth News

In Current Biology, Richard H. ffrench-Constant [Editor’s note: the name is not a typo] and Alex Hayward from the University of Exeter presented a case for industrial melanism that implicates non-coding RNAs, both lncRNAs and microRNAs. The Summary states, 

Melanism drives both crypsis and mimicry in butterflies and moths. To date, melanism has been mapped to a structural gene called cortex, but now more detailed work shows that in fact it is controlled by non-coding RNAs at the same locus.

If anyone thought that the peppered myth was figured out long ago, they should read this embarrassing disclosure:

Melanism is one of the most highly studied examples of natural selection; the switch between coloured and melanic wing scales is involved in industrial melanism in the Peppered moth, Biston betularia, Mullerian mimicry in Heliconius butterflies, leaf-like crypsis in Oakleaf butterflies and seasonal polyphenism in the Buckeye, Junonia coenia. However, the precise mechanism (or alternative mechanisms) controlling the developmental switch between coloured and melanic butterfly scales has remained obscure.

The authors go on to describe activities in the pupa that take place in the dark, where individual wing scales are colorized and sclerotized (hardened). Instead of proposing that the cortex gene had mutated and was naturally selected to favor dark scales on dark tree trunks and light scales on light tree trunks, these two scientists show evidence from three recent papers that wing scales in Lepidoptera are under the control of noncoding RNAs — not the cortex gene. The new picture gets very complicated very fast compared to the simple neo-Darwinian tale.

The importance of miRNAs during butterfly development is supported by recent evidence that two miRNAs regulate the ecdysone pathway in the green-veined white butterfly, Pieris napi, with likely roles in diapause progression. More generally, non-coding RNAs, including miRNAs, may play currently under-appreciated roles as key switches in gene regulatory networks, potentially facilitating adaptive phenotypic evolution, not least in pigmentation and melanisation. For example, multiple studies have implicated miRNAs as upstream switches in melanin production in fish, shellfish, reptiles, and mammals…. Cases in shellfish often affect shell colour, which is involved in various adaptive functions in molluscs, including thermoregulation and camouflage.

Figure 2 in their article shows examples of colorization differences within populations of single species such as llamas, fish, certain shellfish, and human skin. They may call this evolution, but it is a far cry from textbook neo-Darwinism. The “adaptive functions” are regulated, not random.

Given the accumulation of studies implicating miRNAs in melanisation, emergent research challenges are to examine if miRNAs are recruited as key regulators of melanisation more widely across animal diversity, if so why, and the extent to which they act as upstream switches in a wider suite of phenotypic traits.

A Good Example 

We can add our congratulations to Ambros and Ruvkun for opening this window into realities in the cell that no one was expecting. In the early 1990s, neo-Darwinism was king, and the Central Dogma oversimplified genetics. Now, we have learned of much more sophisticated realities: gene networks and their overlapping codes and switches. By thinking outside the box and following the evidence where it led, the two Nobel Prize winners set a good example of breaking through fossilized paradigms and launching new avenues for research. Whether or not the peppered myth survives like a zombie to haunt textbooks again remains to be seen. Meanwhile, those in the know within the design community have additional ammunition for exploring the molecular mechanisms intrinsic to well-designed systems, responsive to the environment, purposefully engineered by a mind with foresight.