This time at the University of Exeter:
Scientists have revisited – and confirmed – one of the most famous textbook examples of evolution in action.
They showed that differences in the survival of pale and dark forms of the peppered moth (Biston betularia) are explained by how well camouflaged the moths are to birds in clean and polluted woodland.
“Industrial melanism” – the prevalence of darker varieties of animals in polluted areas – and the peppered moth provided a crucial early example supporting Darwin’s theory of evolution by natural selection, and has been a battleground between evolutionary biologists and creationists for decades.
The battle was over the claim that differing prevalence of the light and dark varieties is evidence of Darwinian evolution. With no permanent change occurring, it can’t be a serious demonstration. The fact that the moth is cited so often in textbooks is primarily due to an acute shortage of clear cases of Darwinian evolution (as opposed to reversible hybridization and such).
The common pale form of the moth is camouflaged against lichen growing on tree bark. During the Industrial Revolution – when pollution killed lichen and bark was darkened by soot – a darker-winged form emerged in the UK.
Later, clean air legislation reduced soot levels and allowed lichen to recover – causing a resurgence of pale peppered moths.
The example has been well supported by many studies, but nobody had ever tested how well camouflaged the moths were to the vision of their key predators – birds – and how their camouflage directly influenced survival.
Now scientists at the University of Exeter have shown that, to the vision of birds, pale moths are indeed more camouflaged against lichen-covered trees than dark moths – making pale moths less likely to be eaten by birds in unpolluted woodland and giving them an evolutionary advantage.
“This is one of the most iconic examples of evolution, used in biology textbooks around the world, yet fiercely attacked by creationists seeking to discredit evolution,” said Professor Martin Stevens, of the Centre for Ecology and Conservation on the University of Exeter’s Penryn Campus in Cornwall.
Does the professor really believe that, should industrialism return to the area, the proportions would not be reversed over the decades, showing no evolution at all but simply shifting proportions of light vs. dark examples?
“Remarkably, no previous study has quantified the camouflage of peppered moths, or related this to survival against predators in controlled experiments.
“Using digital image analysis to simulate bird vision and field experiments in British woodland, we compared how easily birds can see pale and darker moths, and ultimately determine their predation risk.
“Our findings confirm the conventional story put forward by early evolutionary biologists – that changes in the frequency of dark and pale peppered moths were driven by changes in pollution and camouflage.” Study confirms truth behind ‘Darwin’s moth’” at Featured News
But no one doubted that. The controversy was over whether the shifting proportions can properly be called a form of “evolution.” Most people reasonably expect “evolution” to produce significant and probably irreversible changes, for example, turning dinosaurs into birds.
What I find amazing is how badly they want to rescue this story.
1) “the peppered moth provided a crucial early example supporting Darwin’s theory of evolution by natural selection, and has been a battleground between evolutionary biologists and creationists for decades.” Not really. I mean, even the most literal rendering of Genesis clearly allows for this to be possible. Seeing changes in proportions of variants in a population via natural selection is trivial. The problem we’ve all raised is, the story is wrong.
2) Look at the admissions: “nobody had ever tested how well camouflaged the moths were to the vision of their key predators – birds – and how their camouflage directly influenced survival.” Yet it’s textbook. The abstract of the paper even states, “Despite extensive work, a striking gap remains in that no study has ever objectively quantified their camouflage or related this directly to predation risk.”
What did they actually do? “Using museum specimens, including some of Kettlewell’s original collections, we used digital image analysis and models of avian vision to quantify the camouflage match for colour and luminance…”
Models and stuffed museum specimens. Not exactly a field demonstration. But, certainly, they did that right?
“A widely used and powerful technique is use artificial prey items designed to resemble real animals to predator vision…for monitoring survival over time when presented with an edible component or pinned to natural backgrounds in the field….Artificial moths matching the appearance of typica and carbonaria forms with an edible pastry body were pinned to lichen covered tree trunks…”
And this, this, is their attempt at saving the icon of evolution.
Somebody call the Zombie Patrol!
Even if the classic peppered moth story were 100% true, it would not pose a problem for any form of creationism. Nor would it provide any evidence for DARWINIAN evolution. It would merely show a reversible shift in the proportions of two variants of the same species.
Most peppered moths in the wild do not rest on tree trunks. They rest where they can’t be seen, probably high in the canopies of trees. So tests of their visibility on tree trunks are irrelevant.
Incidentally, there HAVE been previous studies on bird vision and the visibility of peppered moths. The previous studies may not have been as comprehensive and rigorous as the latest one, but they’re all equally irrelevant.
The real story here is that the evidence for Darwinism is so bad that Darwinian propagandists keep trying to breathe life into corpses such as this one. (And, as is so often the case, they manage to con the government into wasting taxpayers’ money on them.)
In fairness, the researchers were using dead moths to produce the zombies, so they got at least that step right. We wrote back to ask Wells about that aspect of the study because it seemed decidedly odd:
To do this, they used museum specimens including some from the collections of Bernard Kettlewell, who conducted famous research on the evolution of the species in the 1950s.
The researchers also created artificial moths, baited them with food and observed predation rates in UK woodland, mostly in Cornwall. “Study confirms truth behind ‘Darwin’s moth’” at Featured News
We also asked Wells, given the assumption that lots of birds eat lots of moths, why couldn’t this test be done in vivo instead of “in zombie-o”? Or do so few moths rest on tree trunks that it is not time-efficient to try to persuade living specimens to behave that way?
A paper published in 1977 listed data on 8,426 peppered moths caught in traps in southern Britain between 1952 and 1972. (Obviously, this would have been only a small percentage of the moths that actually lived in southern Britain during that period.) In 1998 peppered moth expert Michael Majerus published data on 47 moths found in natural resting positions in 32 years; of these, 6 were resting on exposed tree trunks.
Someone hoping to salvage this icon of evolution would have to be crazy to wait around for a moth to rest on a tree trunk.
The Exeter researchers report, “In the experiment using artificial moths, lighter models had a 21% higher chance of “surviving” (not being eaten by birds).” So their point seems to be that, if moths actually rested in open areas, they would be better off to be lighter models.
And to think that some people wonder why Darwinism is doubted…
But would anyone be surprised if this study becomes a sidebar in textbooks for high school as evidence for Darwinian evolution? It’s really becoming a social class thing at this point.
Note: Nature got sucker punched by this one.
See also: Claimed link between creationism and “conspiracism”
Wow. These authors must feel quite threatened. They are really reaching. Their two topics cannot even be equated as concepts: Creationism is a position on a specific subject (origin of life and the universe); conspiracism, which is more commonly called “conspiracy thinking,” is a tendency of thought (it’s all a Big Plot, you see…) which may be applied to any position on any subject.
How does the controversy over Darwinism affect the wider culture? Public understanding of science has been paying the price for the elite’s self-indulgence in looking down on their “Neanderthal” inferiors ever since the Scopes Trial, claiming a science basis. For example, arch-Darwinist Richard Dawkins (of “selfish gene”) fame, was a professor of the Public Understanding of Science, when his notion of a “selfish gene” is essentially mystical and not historical.