Intelligent design is taking ownership of some of the characters in Jonathan Wells’s book Icons of Evolution. Darwinians never had a rightful claim to them.
Rare is any article about peppered moths that does not celebrate them as supreme examples of Darwinian evolution by natural selection. An open-access paper in Nature Communications Biology breaks that mold by focusing on a new skill in this species: the ability to “feel” color. Before adult peppered moths can fly into the tops of trees and challenge Darwinism there (unless they are tacked onto the trunks), they have to live as caterpillars. The Max Planck Institute for Chemical Ecology summarizes new findings about camouflage in the larval stage:
It is difficult to distinguish caterpillars of the peppered moth from a twig. The caterpillars not only mimic the form but also the color of a twig. In a new study, researchers of Liverpool University in the UK and the Max Planck Institute for Chemical Ecology in Germany demonstrate that the caterpillars can sense the twig’s color with their skin. Caterpillars that were blindfolded changed the color of their bodies to match their background. When given the choice of which background to rest on, the blindfolded caterpillars still moved to the background that they resembled. The researchers also found that genes that are required for vision were expressed not only in the eyes of the caterpillars but also in their skin. [Emphasis added.]
Blindfolding a caterpillar: now there’s a challenge for a rainy day! They did it somehow, and when they tested their subjects on artificially colored twigs, the caterpillars mimicked them beautifully. A photo (above) shows dramatic color differences in these caterpillars, from near white to near black, all matching the artificial twigs they rest on. That’s an amazing trick to do blindfolded. Apparently, “genes that are required for vision were expressed not only in the eyes of the caterpillars but also in their skin.” This implies that the caterpillars can sense both light and color through the skin. The eye genes were found expressed in every body segment, sometimes more than in the eyes themselves.
When moved from twig to twig, caterpillars changed their color to match the twig.
“It was completely surprising to me that blindfolded caterpillars are still able to pick a branch that best matches their color. I don’t think my supervisor, Ilik Saccheri, believed me until he saw it by himself”, says Amy Eacock, one of the lead authors of the new study and currently a postdoc at the Max Planck Institute for Chemical Ecology.
References to Darwin and natural selection are lacking in the formal paper, although it gives some passing hat tips to evolutionary dogma, e.g.: “The peppered moth (Biston betularia) has evolved to be highly cryptic to visual predators, both in the adult and larval stages.” But even so, the next sentences are more favorable to a design perspective:
Crypsis is achieved through contrasting mechanisms in each stage. The adult colour pattern polymorphism (melanism) is genetically determined, while the larvae camouflage through a combination of twig-mimicking masquerade and colour plasticity. Colour change in these polyphagous larvae is a continuous reaction norm in response to colour cues from the twigs in the larvae’s immediate surroundings rather than the leaves they eat. The precision of this colour and pattern response is at odds with the simple larval ocelli, and the distal position of the head relative to the twig when larvae are in the resting pose. We conjectured that the larvae could be using an additional visual sense.
Intrigued by the observations, the scientists were motivated to understand a “sophisticated system” in these caterpillars. Did Darwin’s theory help? Only by supplying glittering generalities, like “the predators drove them to it.” Does that makes sense in the light of evolution?
Our results significantly expand the current view of dermal light sense to include slow colour change, raising intriguing questions about the evolutionary sequence of pathway recruitment and modification that has culminated in this sophisticated system of extraocular photoreception and phenotypic plasticity, driven by a predator–prey evolutionary arms race.
Any flying bird should be admired for its magnificent integration of complex systems that allow powered flight: musculature, a specialized skeleton, sense organs, perching feet, brains, digestive systems, reproductive systems, and streamlined morphology, to name a few. Beak size can become a deal-breaker in a drought, but for evolutionists to focus on millimeter-size changes in finch beaks, yet fail to account for all the other systems, is, as Michael Behe quipped, like worrying about the cents columns in hundred-thousand-dollar transactions.
A study by the University of Cincinnati found that Charles Darwin’s famous finches defy what has long been considered a key to evolutionary success: genetic diversity.
The research on finches of the Galápagos Islands could change the way conservation biologists think about a species’ potential for extinction in naturally fragmented populations. [Emphasis added.]
The UCI biologists published a paper in Conservation Genetics pointing out their findings. They gathered DNA from museum specimens and from living ones on the islands. What they found turns earlier beliefs upside down. It confirms that the birds are devolving, despite genetic diversity:
In this study, we compared ancient DNA from ~ 100 year old extinct and extant Darwin’s finch populations in the Galápagos Islands to determine whether single time point genetic assessments in the past accurately predicted extinction risk, or if other factors such as metapopulation dynamics could mask population declines. Of eight extinct populations, only one had significantly reduced genetic variation compared to an extant population of similar characteristics. Contrary to our prediction that populations would have decreased genetic diversity prior to extinction when compared to persisting populations, at least one measure of genetic diversity was significantly higher in six of the eight extinct populations when compared to extant populations.
As the headline says, “Genetic diversity couldn’t save Darwin’s finches.” Some of the varieties that are extinct now had higher genetic diversity 100 years ago than living ones today. According to standard evolutionary theory, they should have had higher fitness, but all that genetic potential for evolution wasn’t much help. There goes a simplistic assumption in evolutionary theory — the sound of one wing flapping.
In Zombie Science, Jonathan Wells added the human eye to his new list of icons, because a myth had arisen that two evolutionists used a computer model to reveal an easy path from simple eyes to complex eyes. That turned out to be false, but in Chapter 7, Wells went further back to the first eyes in the fossil record. Wells pointed out that the eyes of trilobites were “already of a highly-developed type” with lenses that “represent an all-time feat of function optimization” (p. 133).
We can now add more detail to this argument against Darwinism. Paleontologists at Lund University in Sweden were surprised to find eumelanin in the eyes of a fossilized crane fly, some 54 million years old. “The composition of fossil insect eyes surprises researchers,” they report, because “It was previously assumed that melanic screening pigments did not exist in arthropods.”
“We were surprised by what we found because we were not looking for, or expecting it”, says Johan Lindgren, an Associate Professor at the Department of Geology, Lund University, and lead author of the study published this week in the journal Nature.
The researchers went on to examine the eyes of living crane-flies, and found additional evidence for eumelanin in the modern species as well.
In other words, there wasn’t any evolution from the fossil crane fly to living crane flies. Now here’s the kicker: given that crane flies had eumelanin, other arthropods probably did, too — including the first arthropods in the Cambrian explosion, e.g., trilobites. Paleontologists had thought the trilobite eye was composed of single crystals of calcium carbonate. That would have been unique and different from modern arthropod eyes, giving evolutionists an opportunity for storytelling. But since the fossil crane fly also had crystals of calcium carbonate, unlike the organic eyes of living crane flies, the scientists conclude that the calcium carbonate was a result of the fossilization process. Thinking backward, that leads to a similar conclusion about trilobites that are ten times as old as the crane fly fossil:
This, in turn, led the researchers to conclude that another widely held hypothesis may need to be reconsidered. Previous research has suggested that trilobites — an exceedingly well-known group of extinct seagoing arthropods — had mineralized lenses in life.
“The general view has been that trilobites had lenses made from single calcium carbonate crystals. However, they were probably much more similar to modern arthropods in that their eyes were primarily organic”, says Johan Lindgren.
The Icons Are Falling
When examined in more detail, the icons of evolution turn into evidences for intelligent design: complex eyes that appear at the beginning; birds with powered flight; and caterpillars that can see color blindfolded. Scientists and teachers should stop pointing to these outworn symbols of Darwinian evolution, which is “still a theory in crisis” (Denton) and “almost certainly false” (Nagel). When continuing research weakens iconic evidences for evolution, it’s a sign of a weak theory.
Photo credit: Arjen van’t Hof, University of Liverpool, via EurekAlert!