Showing posts with label Just-so stories. Show all posts

Fossil Find: Fungus Controlled Ant Just Like Today


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The fossil record cannot usually tell us about the soft body parts or the behavior of its specimens. For these, we look to the extant species. But now a clever finding reveals an odd behavior in carpenter ants from the distant past.

Nature is full of designs and behaviors not easily preserved in the fossils. Consider the bat, certain types of which map out objects around it as small as a mosquito by sensing the echoes of its own squeaks—a system known as echolocation. The bat emits a high-pitch squeak, well beyond the range of human hearing, up to 2,000 times per second. Next it determines both range and direction to the tiny mosquito by sensing the echo while filtering out echoes from the squeaks of nearby bats. Or consider fish that use underwater electric fields either passively or actively to sense objects around them, including other fish.

It is difficult to determine such details from the fossil record, but they reveal how unlikely is the theory of evolution. Anyone familiar with today’s sonar or radar systems knows the immense complexity involved with such systems: the problems of sensing the echo in the presence of the transmitted signal which can be billions of times stronger, of filtering out spurious signals such as echoes of older transmissions, of combining the echo information with knowledge of your own motion, and so forth. Yet the bat’s detection abilities are superior to those of the best electronic sonar equipment.

It is also difficult to determine complex behaviors from the fossil record. Consider certain Hydra species, a small underwater creature, that develop nematocysts—stinging cells which eject a tiny poisoned hair. A planarian worm known as the Microstomum, consumes Hydra but passes the nematocysts through its digestive system and positions them on its surface. The Hydra meal serves to arm the Microstomum, and when fully equipped the Microstomum omits the Hydra from its diet, resuming again after discharging its ill-gotten arsenal.

For evolution to have formed this system, certain Microstomum must have happened to have selectively digested the Hydra, leaving the nematocysts untouched. Then they also happened to have vectored the nematocysts to the surface and positioned it there. Then certain Microstomum happened to have a feedback loop installed to regulate its diet.

Or consider a sheep parasite known as the brainworm:

The brain worm that reproduces in sheep uses ants to get back into a sheep. The worms get into ants by infecting snails that eat sheep feces. The snails expel tiny worm larvae in a mucus that ants enjoy, and some dozens of worms take up residence in an ant. But this would do them no good if the ant behaved normally; too few ants would be eaten by sheep. Consequently, while most of the worms make themselves at home in an ant’s abdomen, one finds its way to the ants brain and causes the ant to climb up a grass stem and wait to be eaten by a sheep. Ironically, the worm that programs the ant is cheated of happiness in the sheep’s intestine; it becomes encysted and dies.

The whole procedure seems unnecessary. Why do the worm eggs defecated by the sheep not simply hatch and climb up the grass stem to await being eaten by a sheep instead of making the hazardous trip through snail and ant? How could they become adapted to being carried by the ant unless the ant were already programmed to make itself available to be eaten by a sheep?

The list, of course, goes on and on. There is the decoy-fish with its detachable dorsal fin that mimics a smaller fish complete with a dark spot resembling an eye and notch resembling a mouth. The decoy-fish becomes motionless except for the decoy which moves from side to side, causing the “mouth” to open and close. And there is the owl with ears tuned to different frequencies, to better track its prey, and the rattlesnake with heat-sensitive (infrared) sensors to image its prey at night.

Now, a new fossil finding shows just how persistent nature's odd behaviors can be. A carpenter ant (Camponotus leonardi) can be infected by the fungus Ophiocordyceps. Sensitive to the forest temperature and humidity, the fungus must be up off the ground but lower than the forest canopy. It arrives at the desired height by taking over the ant it infects:

The fungus cannot grow high up in the canopy or on the forest floor, but infected ants often die on leaves midway between the two, where the humidity and temperature suit the fungus. Once an ant has died, the fungus sprouts from its head and produces a pod of spores, which are fired at night on to the forest floor, where they can infect other ants.

Scientists led by Hughes noticed that ants infected with the fungus, Ophiocordyceps unilateralis, bit into leaves with so much force they left a lasting mark. The holes created by their mandibles either side of the leaf vein are bordered by scar tissue, producing an unmistakable dumb-bell shape.

It is another fascinating parasitic action that, it would seem, could never be found in the fossil record. But a team of intrepid researchers found a way:

Writing in the journal, Biology Letters, the team describes how they trawled a database of images that document leaf damage by insects, fungi and other organisms. They found one image of a 48m-year-old leaf from the Messel pit that showed the distinctive "death grip" markings of an infected ant. At the time, the Messel area was thick with subtropical forests.

"We now present it as the first example of behavioural manipulation and probably the only one which can be found. In most cases, this kind of control is spectacular but ephemeral and doesn't leave any permanent trace," Hughes said.

And how did evolution design such a Rube Goldberg device? Who knows:

"The question now is, what are the triggers that push a parasite not just to kill its host, but to take over its brain and muscles and then kill it."

He added: "Of all the parasitic organisms, only a few have evolved this trick of manipulating their host's behaviour.

Evolution is truly amazing. It creates in ways we cannot even figure out.

Religion drives science and it matters.

No Imagination Shortage


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In his piece Reclaiming the Imagination, Oxford's Timothy Williamson argues for more imagination in science. As part of his introduction, the Wykeham Professor of Logic considers our ability to imagine:

Why did humans evolve the capacity to imagine alternatives to reality? Was story-telling in prehistoric times like the peacock’s tail, of no direct practical use but a good way of attracting a mate?

Here Wykeham inadvertently undercuts his premise. There is no shortage of imaginative story-telling in evolutionary thought. Asking evolutionists to reclaim the imagination would be like telling five year olds they need more play time, or telling alcoholics that they need more cheap wine. Yes, imagination is a good thing, but let's start with some realism.

Butterflies and Flashlights


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I once met a fellow who was an aficionado of, believe it or not, flashlights. It seemed rather mundane until I saw all the neat designs using LEDs (light emitting diodes). These semiconductor devices have been greatly improved in recent years and are finding a wide range of uses. But as is so often the case, these technological advancements were there all along in the biological world. In this case, certain butterfly species have their own elaborate optical emission system in their wings. As one researcher put it, “Who knows how much time could have been saved if we'd seen this butterfly structure 10 years ago.”

Up until a few years ago the problem with LEDs was that most of the light was not emitted. This inefficiency was resolved with two-dimensional crystals and layered reflectors called distributed Bragg reflectors (DBRs). And like these high-emission LEDs, scales on the wings of African Swallowtail butterflies make up a two-dimensional photonic crystal enhanced by a three-layer, cuticle-based DBR. The photonic crystal is infused with highly fluorescent pigment and contains an array of hollow air cylinders arranged in a pattern of triangular symmetry. As one paper further explains:


As in ultra–high-efficiency LEDs, these Butterflies’ DBRs support a spectral stop band that matches the peak emission from the structure above it. The DBRs reflect upwardly the downward-emitted fluorescence concurrently with non absorbed longer wavelengths pass through the PCS. The spatial separation between the DBR and PCS minimizes losses via coupling to guided modes in the DBR. Excitation for this fluorescent material appears to be optimized for the radiance from blue skylight, which peaks around 420 nm. Additionally, because the alpha-absorbance band of rhodopsin dominates the green wavelength photosensitivity of Papilio vision, the spectral form of this absorption is ideally placed for stimulation by fluorescence from conspecific wings. As with some shrimps and birds, this enhances signaling, because absorption of visually less productive short wavelengths leads to the emission of longer wavelengths that trigger photoreception.

As the passage explains, the butterfly’s optical emission system is tuned to use sunlight and to maximize visibility. Here is a less technical description of the system:


The trouble with this mechanism is that while half the fluorescent light radiates away from the butterfly, the other half radiates into the wing structure. That half of the light would be lost were it not for the extraordinary structure of the scales.

Vukusic discovered that the base of each scale is a highly efficient three-layered mirror—a structure known as a distributed Bragg reflector. Light from the pigment bounces between these layers, interferes constructively, and then escapes in the direction it came from.

Distributed Bragg reflectors are not perfect, however; some light always becomes trapped on the surface of the reflector and is lost. But the butterfly has another neat trick to get around this. Vukusic and his colleague Ian Hooper discovered that in each scale, sitting just above the mirror, is a slab of material filled with hollow cylinders of air that run perpendicular to the mirror. These cylindrical holes channel the light away from the reflector, preventing it from getting trapped. The slab, says Vukusic, is what optical physicists call a photonic crystal.

The end result is a highly specialized structure that converts skylight into blue-green light, captures this light, and finally channels it out to act like plumage to attract female butterflies.

Was this remarkable system constructed by the blind interplay of natural processes? Evolutionists think so. In fact they are certain it was, though beyond vague speculation they don’t know how.

Evolutionists speculate that perhaps these marvels happened to arise luckily via random mutations. Or perhaps self-assembly and mechanical processes such as buckling, cracking and splitting are important factors. In fact, perhaps pre existing cellular structures serendipitously provide a manufacturing framework. Could it be that “the highly complex inverse opal-type structures could appear ‘suddenly’ in evolutionary time (without having to evolve stepwise)”? Amazingly this is what one finds in evolutionary theory--unfounded speculation underwritten by dogmatic certainty.

Perhaps flashlights also appeared suddenly. Religion drives science, and it matters.