Tag Archives: Darwinism

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Target acquisition and interception in dragonflies

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Here is a fascinating post about some of the capabilities of dragonflies from Evolution News.

Selective attention

First, dragonflies have “selective attention” – the ability to focus on a single prey and ignore other distractions:

Dragonflies are among the best flyers in the insect world. Their twin pairs of paper-thin wings allow them to hover and move in all directions, even in mating. When the time comes to dart after prey at high speed, they rarely miss.

What’s their secret? One is “selective attention” — a trait previously known only in primates, according to new research from the University of Adelaide, Australia. Selective attention is the ability to focus on one object and exclude others. Just as a tennis player must focus on the ball and ignore the cheers of the crowd, a dragonfly must pick out one target from a swarm of insects and avoid being distracted by all the others.

Here’s a snip from the research paper:

Our data make a compelling case that CSTMD1 reflects competitive selection of one target. We emphasize “competitive,” because the attended target is not always the same between trials or even within a trial, as seen in strikingly perfect switches from one to the other…. Competition is further suggested by rare examples where the activity observed under Pair stimulation initially lags both T1and T2 responses… suggesting initial conflict in the underlying neural network before resolution of competition by a “winning” target.

We previously showed that CSTMD1 still responds robustly to a target even when it is embedded within a high-contrast natural scene containing numerous potential distracters. Taken together with recent evidence that the behavioral state of insects strongly modulates responses of neurons involved in visuomotor control, our new data thus suggest a hitherto unexpected sophistication in higher-order control of insect visual processing, akin to selective attention in primates.Perhaps the most remarkable feature of our data is that once the response “locks” onto a target (or following a switch), the second target exerts no influence on the neuron’s response: the distracter is ignored completely.

In order to succeed at the task of catching its prey, the dragonfly has to tune out all other distractions.

Target selection

In addition, dragonflies have the ability to intercept a target in mid-air – similar missile defense systems on AEGIS cruisers and destroyers.

The Evolution News article explains:

Another paper on dragonflies shows that these marvels of the insect world are equipped with navigational equipment that can do vector calculus. In the Proceedings of the National Academy of Sciences, Gonzalez-Bellido and a team at the Howard Hughes Medical Institute discerned “Eight pairs of descending visual neurons in the dragonfly [that] give wing motor centers accurate population vector of prey direction.”

Intercepting a moving object requires prediction of its future location. This complex task has been solved by dragonflies, who intercept their prey in midair with a 95% success rate. In this study, we show that a group of 16 neurons, called target-selective descending neurons (TSDNs), code a population vector that reflects the direction of the target with high accuracy and reliability across 360°. The TSDN spatial (receptive field) and temporal (latency) properties matched the area of the retina where the prey is focused and the reaction time, respectively, during predatory flights. The directional tuning curves and morphological traits (3D tracings) for each TSDN type were consistent among animals, but spike rates were not. Our results emphasize that a successful neural circuit for target tracking and interception can be achieved with few neurons and that in dragonflies this information is relayed from the brain to the wing motor centers in population vector form.

What did I make of this? Well, evidence like this always causes me to think aboutthe reality of God, and the disturbing thought that we do not live in an accidental universe where I can do whatever I want and be accountable to no one. It’s easier to believe that – it requires less work and it frees us to be our own boss and make our happiness the first priority. As individuals, it’s very tempting for us to think that we are number one, and to resent our obligations to anyone else. The problem is that the scientific data doesn’t support that worldview. The facts are what they are and it is up to us, now, to try to find out who the designer is and what he wants from us.

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Remembering “The Piltdown Man” – 100 years later

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Have the Darwinian faithful ever been so optimistic about their theory that they stretched the evidence dishonestly? Well, yes, there have been instances of “hiding the decline” in the biological sciences.

Here’s one described in the Seattle Times: (H/T Evolution News)

Tuesday is the centennial of the grossest fraud of 20th-century science: Piltdown man. It is a case worth remembering.

On Dec. 18, 1912, amateur geologist Charles Dawson presented to the Geological Society of London a partial skull. It was purported to be a human ancestor 500,000 to 1 million years old, an age scientists now assign to Homo erectus. Dawson said he had found the fossils in a gravel pit near Piltdown Common, south of London.

Dawson had no scientific credentials, but his friend Arthur Smith Woodward did. Woodward was the keeper of the geological department at the British Museum. He had been at the dig and had seen the jawbone “fly out” of the ground under the blow of Dawson’s pick.

There was a problem with the jawbone. It was from an orangutan only a few hundred years old. It was fitted with two fossilized chimpanzee teeth, filed down to make them look more like human teeth. The cranium fragments were human, from the Middle Ages. All had been treated with an iron solution and acid to make them look older.

Scientists didn’t have many fossil skulls in 1912, but none of them looked like a human cranium with an ape jaw.

Several scientists, including one from the Smithsonian Institution, argued that the jaw and cranium did not match. It took 40 years for them to be proved right, and even longer for Dawson to be confirmed as the con man responsible.

The surprising thing is that this is not the only time that this has happened with Darwinists and global warmists.

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New paper in Nature: Ediacaran fossils not ancestors of Cambrian fauna

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Uncommon Descent reports on a new paper in the most prestigious peer-reviewed science journal.

Excerpt:

A new paper has just been published in Nature by Gregory J. Retallack of the University of Oregon. The paper argues that the Ediacaran fauna are not ancestral to the animals which arose in the Cambrian explosion and that life existed on land 65 million years before previously thought. Retallack further argues that the iconic fossils of Dickinsonia and Springgina, which appear in the Precambrian Ediacaran assemblages, were not in fact animals at all. Rather they were, according to Retallack, lichens, soil structures and traces of slime moulds.

And they link to this post about the paper from Science Daily, which makes the significance of the discovery even clearer:

Ancient multicellular fossils long thought to be ancestors of early marine life are remnants of land-dwelling lichen or other microbial colonies, says University of Oregon scientist Gregory J. Retallack, who has been studying fossil soils of South Australia.

[…]”This discovery has implications for the tree of life, because it removes Ediacaran fossils from the ancestry of animals,” said Retallack, professor of geological sciences and co-director of paleontological collections at the UO’s Museum of Natural and Cultural History. His evidence, mostly gathered from a site in the Flinders Ranges, is presented in a paper placed online ahead of print by the journal Nature.

“These fossils have been a first-class scientific mystery,” he said. “They are the oldest large multicellular fossils. They lived immediately before the Cambrian evolutionary explosion that gave rise to familiar modern groups of animals.”

Retallack studied numerous Ediacaran fossils and determined that the diversity reflects a preference by the ancient organisms for “unfrozen, low salinity soils, rich in nutrients, like most terrestrial organisms.” Thus the fossils in Australia’s iconic red-rock ranges, he concludes, were landlubbers. In his closing paragraph, Retallack outlines implications for a variety of other Edicaran fossils, that could have been lichens, other microbial consortia, fungal fruiting bodies, slime molds, flanged pedestals of biological soil crusts, and even casts of needle ice.

Ediacaran fossils, he said, represent “an independent evolutionary radiation of life on land that preceded by at least 20 million years the Cambrian evolutionary explosion of animals in the sea.” Increased chemical weathering by large organisms on land may have been needed to fuel the demand of nutrient elements by Cambrian animals. Independent discoveries of Cambrian fossils comparable with Ediacaran ones is evidence, he said, that even in the Cambrian, more than 500 million years ago, life on land may have been larger and more complex than life in the sea.

Here’s a quick re-cap of the Cambrian explosion:

Part 1: (7:50)

Part 2: (3:25)

This explosion in biological complexity fits nicely with an intelligent designer . Intelligent agents make information by sequencing symbols into functional instructions. That’s what new body plans are. It’s like new software, and new software requires a software engineer.

The standard naturalist response to this problem of sudden origins of anaimal body plans used to be that the Cambrian explosion did have precursors. The precursors were thought to be the Ediacaran fossils. But that’s all been shot to Hell now, with this new paper in Nature. Ooops!