On reductionism: Pros and Cons.

 

The appeal to engineerless engineering continues to fail..

 Sophisticated Precision in Fruit Fly Sensory Systems

David Coppedge

Last week, we considered the signal “wave” that controls development of the compound eyes in fruit flies and the motor neurons that control their rapid zigzag turns in the air. Pilots have to learn the forces of lift, drag, and thrust, and know how to prevent stalls. They know that rapid banking turns vastly increase G-forces and come with a high risk of stalling. Aerobatic know-how comes built-in for fruit flies. The same is true for all unrelated animals that perform powered flight, whether mammal (bat), reptile (pterosaur), or bird.

Smell Sense

The miniature insect flyers around us also have good olfactory organs that help them smell where to go. They smell good (or well, for you grammarians).

A news item from Ruhr University Bochum in Germany tells, “How Fruit Flies Smell CO2.” This commands our attention. Could fruit flies offer solutions for climate change monitoring? The scientists are inspired by the fly’s sensing ability.

The new findings are to be incorporated into the development of a CO2 biosensor, which the Bochum team is researching in cooperation with the Institute of Aircraft Systems in Stuttgart. “This should enable us to detect CO2in liquid media, which is something that as yet can’t be done,” says Störtkuhl. CO2 sensors are used on the International Space Station, for example, where they must consume as little energy as possible. Given that physical measurement methods are not very energy-efficient, a biosensor could be a great alternative.[

Notice the higher rank bestowed on biological sensors. A biosensor might be able to detect other volatile molecules. And so, curiosity rises about how fruit flies smell carbon dioxide, and why they need to. Some readers may be aware that mosquitoes follow the CO2 in human breath to find their victims. Fruit flies smell CO2 emissions from fermenting fruit for their needs. 

Since CO2 is ubiquitous in the atmosphere, flying insects must be able to detect elevated concentrations along a gradient. The tiny insects’ expertise at finding and following carbon dioxide plumes in the air leads to suspicions of sophisticated systems for detecting the “odorless” gas that we humans exhale with each breath. (Thank goodness it is odorless to us.) So, how do they do it? We look at the paper in PLOS One for answers.

Answer: They’re not sure. The team found two receptors on the third segment of the fly’s antennae that respond strongly to bicarbonate CO2 emissions when those receptors are encoded in frog eggs. The response, however, depends on the mix of receptors.

We found that application of sodium bicarbonate evokes large inward currents in oocytes co-expressing Gr21a and Gr63a. The receptors most likely form hetromultimeric [sic] complexes. Homomultimeric receptors of Gr21a or Gr63a are sufficient for receptor functionality, although oocytes gave significantly lower current responses compared to the probable heteromultimeric receptor.

They also found that citronellol blocks the receptors — good to know for manufacturers of insect repellants.

Taste Sense

In fruit flies, the gustatory and olfactory senses overlap. Dr. Roman Arguello at Queen Mary University of London has been “delving into the genes and cells behind their delicate noses and tongues,” finding that the insects are able to adapt their senses to their environments. He likens it to one fly responding to a ripe peach as if it “tastes and smells like tangy vinegar to one fly, but like a burst of summer to another.” It’s quite common in fruit flies, he says, which inhabit a variety of habitats. But is this evolution?

“It’s like finding hidden islands of diversity within a vast ocean of uniformity,” says Dr Arguello. “These changes in gene expression tell us about the evolution of new smells, new sensitivities, and even new ways of using scent to navigate the world.”

Again,

“These findings open up exciting new avenues for understanding how sex differences evolve and how they impact animal behavior,” says Dr Arguello.

But does this research published in Nature Communications really provide “valuable insights into the general principles of how sensory systems evolve,” as they claim? 

All they found were changes in gene expression — not mutated genes that were naturally selected as Darwinian theory requires. The paper only mentions mutations four times (pleiotropic mutations, at that), but “evolution” 144 times. As for “selection,” most of the 14 mentions involved stabilizing selection (i.e., keeping things the same), not the positive selection required for novelty and innovation. The only mentions of “positive selection” were from another study that contradicted this team’s finding of predominantly “evolutionary constraint.” They had no word on how taste receptors originated in the first place.

Directional Sense

Returning to the fundamental aspect of flight (flies do fly), another paper, this one in Nature, discusses the directional sense in these tiny aerobatic insects. Mathematicians will enjoy the abstract from this paper:

To navigate, we must continuously estimate the direction we are headed in, and we must correct deviations from our goal. Direction estimation is accomplished by ring attractor networks in the head direction system.However, we do not fully understand how the sense of direction is used to guide action. Drosophila connectome analyses reveal three cell populations (PFL3R, PFL3L and PFL2) that connect the head direction system to the locomotor system. Here we use imaging, electrophysiology and chemogenetic stimulation during navigation to show how these populations function. Each population receives a shifted copy of the head direction vector, such that their three reference frames are shifted approximately 120° relative to each other. Each cell type then compares its own head direction vector with a common goal vector; specifically, it evaluates the congruence of these vectors via a nonlinear transformation. The output of all three cell populations is then combined to generate locomotor commands.

For non-mathematicians, we can just recall the coach’s advice in many sports to turn your head in the direction you need to go. Fruit flies automatically know this, because specific cells are doing vector calculus and nonlinear transformations, then giving commands to the legs and wings. If building a robot, this would require some engineering know-how:

Accurate navigation requires us to fix a goal direction and then maintain our orientation towards that goal in the face of perturbations. This is also a basic problem in mechanical engineering: how can we keep the angleof some device directed at a target? One solution to this problem is to use a resolver servomechanism to measure the discrepancy or error between the current angle and the goal angle.

The eight researchers describe how fruit flies keep focused on the goal. They create a model and compare it to live data from fruit fly behavior. Why is a transformation needed? Because, they say, motor commands must convert their coordinates from allocentric space (other-directed) to egocentric space (self-directed). 

This poses a coordinate transformation problem. Here we describe a network that solves this problem. This network creates two opponent copies of the allocentric head direction representation, with equal and opposite shifts (θ ± shift). Each copy is then separately compared with an allocentric goal representation, to measure congruence with the goal. The difference between the two opponent congruence values becomes an egocentric motor command.

The PFL3R and PFL3L cell populations take care of this. But there was a surprise finding:

At the same time, our results highlight the unexpected role of PFL2 cells. These cells provide a solution to a classic problem — namely, the fundamental tradeoff between speed and accuracy. High feedback gain allows a system to converge quickly towards its goal, and so it makes sense that gain should be high when error is large, that is, when there is a large discrepancy between the system’s current state and its goal. However, high gain can cause overshooting of the goal, especially when error is already small. We show that PFL2 cells effectively adjust the system’s gain, depending on the magnitude of the system’s current error.

Wow. That should be enough to make us all pause before swatting. CO2 sensors on the antenna, taste sensor gene regulators that adapt to the environment, and vector calculus in the head and legs — how does all this sensory engineering fit into such a tiny fly? The authors had almost nothing to say about evolution, leapfrogging over it with this statement, “the idea that a neuron’s inputs are adjusted (over development and/or evolution) to fit into some standard dynamic range dictated by the biophysical properties of a typical neuron….”

While admiring the humble fruit fly, let us take a moment to marvel at the human mind that can figure these things out. The next time you see a tiny fly or gnat, imagine inventing tools to study those itty-bitty eyes, wings, and antennae — to say nothing of the genes and proteins regulating them — and figure out how they work, using models and mathematical functions. Our sensory capabilities are well-designed, too.

Making the elegant the enemy of the obvious?

 Vilenkin: A Physicist in Flight from Intelligent Design

Evolution News

In his discussion with Robert Lawrence Kuhn at Closer to Truth, Tufts physicist and cosmologist Alexander Vilenkin addresses the question, “Is the Universe Fine-Tuned for Life and Mind?” Kuhn asks:

If the deep laws of the universe had been ever so slightly different human beings wouldn’t, and couldn’t, exist. All explanations of this exquisite fine-tuning, obvious and not-so-obvious, have problems or complexities. Natural or supernatural, that is the question.

Vilenkin — who is also a professor of evolutionary science — concedes the main point:

Alexander Vilenkin: [0:40] “Well yeah that’s right. It appears that the Universe is fine-tuned in the sense that there are about 30 constants of nature which take some specific value: if you look at these numbers, they look like totally random numbers. However, if you change these numbers even slightly, the properties of our universe would change quite dramatically so…”

Robert Lawrence Kuhn: “Generally for the bad.”

Alexander Vilenkin: “Yes, generally for the bad and the question is, what do we make of that?”

Vilenkin then introduces the idea that there might be a multiverse in which our universe, one of many, just happens to have these constants. But he admits that efforts to derive the 30 constants from a fundamental theory have failed [7:11]: “There is no question that despite tremendous effort to explain the constants of nature from fundamental theory, there is very little to show for that effort.” 

But what about the more basic cosmological constant?

Should the Cosmological Constant be Close to Zero?

Vilenkin rejects the idea that the universe is designed, in part because the cosmological constant — a repulsive force that acts against gravity — does not have a “special value” like zero or nearly zero:

Alexander Vilenkin: [9:36] “It is hard to disprove that the value was selected by design but it does look like it is a product of entropic selection. The reason is that there is a range of values of the cosmological constant that is consistent with the formation of galaxies and evolution of life This is a narrow range which includes zero actually. And if it is a random selection (and) you have many regions with different values of this cosmological constant, we expect to find ourselves somewhere in the middle of that range. And this is actually what we observe. So what we observe is perfectly consistent with this such random entropic selection. On the other hand, if you think of design, I would think that design would choose some more special value, for example zero, and in fact if the value of the cosmological constant were fine-tuned, more for example much closer to zero than it is, it would be very hard to explain it through the multiverse hypothesis and that would be evidence against this hypothesis.”

What Is the Cosmological Constant?

It’s really hard to know. The constant is generally represented as an equation. But much about it is unclear. From science writer Adam Mann:

The cosmological constant is presumably an enigmatic form of matter or energy that acts in opposition to gravity and is considered by many physicists to be equivalent to dark energy. Nobody really knows what the cosmological constant is exactly, but it is required in cosmological equations in order to reconcile theory with our observations of the universe.

ADAM MANN, WHAT IS THE COSMOLOGICAL CONSTANT?, LIVE SCIENCE, FEBRUARY 16, 2021

Cosmologists use it, Mann says, because they “may not know what it is, but they know that they need it to make the universe make sense.” At Scientific American, it was described in 2021 as “physics’ most embarrassing problem.”

If We Don’t Know What It Is, How Do We Know It Should Equal Zero?

Experimental physicist Rob Sheldon writes to offers some thoughts:

The cosmological constant, also known as dark energy, arises from Big Bang models that have acceleration, where the expansion of the universe is speeding up with time. This is just one of many models of the universe. The observational data supporting this model was so lacking, a Nobel Prize was offered to anyone who could find evidence for it. Perlmutter, Reiss and Schmidt used 75 type Ia supernovae to argue that acceleration was there, and received the Nobel Prizein 2011. But Subhir Sarkhar used >2000 SNIa in a paper in 2021 to show that the acceleration was consistent with zero…

Not only is this “Dark Energy constant” not well supported theoretically (the simplest derivations are 120 orders of magnitude too big), it isn’t even well supported experimentally.

Rather than admit there is something wrong with the model (which shows the power of consensus thinking), Alexander Vilenkin argues for a multiverse to avoid a Designer. But in a multiverse, everything is possible, including Designers. So I really don’t see this as a logical atheistic solution. It reeks of terrified desperation.

So the arguments against the idea that our universe was designed amount to 1) a speculation that there might also be countless flopped universes out there; and 2) a claim that there is a cosmological constant that should equal zero but doesn’t. But the claims for a cosmological constant are not well supported theoretically.

If you are not an ideological materialist atheist, it would make more sense just to assume that our universe is designed because of the clear evidence for fine-tuning. All the rest is up for debate.

Yet more on one of our planet's other civilization.

 Ants “Think” Differently from Humans

Evolution News

There are some 20 quadrillion ants living in the world today. John Whitfield offers an essay at Aeon on the factors underlying the successful spread of vast colonies from, say, South American to Europe — by piggybacking on human journeys.

Whitfield, author of Lost Animals: The Story of Extinct, Endangered and Rediscovered Species (Welbeck 2020), resists the temptation to compare ant dominance to human dominance of the globe, in part because, well, ants think differently. Here are a couple of the questions he answers in his sparkling and informative essay:

Why Do Ants Work So Well Together?

Recognition looks very different for humans and insects. Human society relies on networks of reciprocity and reputation, underpinned by language and culture. Social insects — ants, wasps, bees and termites — rely on chemical badges of identity. In ants, this badge is a blend of waxy compounds that coat the body, keeping the exoskeleton watertight and clean. The chemicals in this waxy blend, and their relative strengths, are genetically determined and variable. This means that a newborn ant can quickly learn to distinguish between nest mates and outsiders as it becomes sensitive to its colony’s unique scent. Insects carrying the right scent are fed, groomed and defended; those with the wrong one are rejected or fought.

JOHN WHITFIELD, “ANT GEOPOLITICS,” AEON, FEBRUARY 16, 2024

As Eric Cassell notes in Animal Algorithms: Evolution and the Mysterious Origin of Ingenious Instincts (2021) , all species of ants are social; there are no known solitary ants.

How Different Is Ants’ Way of Thinking?

The more I learn, the more I am struck by the ants’ strangeness rather than their similarities with human society. There is another way to be a globalised society — one that is utterly unlike our own. I am not even sure we have the language to convey, for example, a colony’s ability to take bits of information from thousands of tiny brains and turn it into a distributed, constantly updated picture of their world. Even ‘smell’ seems a feeble word to describe the ability of ants’ antennae to read chemicals on the air and on each other. How can we imagine a life where sight goes almost unused and scent forms the primary channel of information, where chemical signals show the way to food, or mobilise a response to threats, or distinguish queens from workers and the living from the dead? 

WHITFIELD, “ANT GEOPOLITICS”

Cassell suggests that colony communication is somewhat like a computer algorithm: The ant processes pheromones (scent signals) as if they were AND gates and STOP in a computer system (p. 91). Thus, the ant is not judging the situation and deciding whether to go along with the group or not — as a human might — but rather, processing a signal. Stanford entomologist Deborah M. Gordon calls the resulting communication without personal understanding the “anternet.”

Whitfield tells the story of Biosphere 2, a giant terrarium in Arizona, designed in the 1980s as a self-sustaining living system with no connection to the outside world. Developed to test the design of biospheres for space exploration, it fell victim in 1996 to the southeast Asian black crazy ant, which turned it into a honeydew factory.

So sometimes, sheer numbers and a viable social algorithm win out over high individual intelligence. But, in fairness, the eight humans who lived inside Biosphere 2 for two years did not seem to enjoy it much:

More Darwinian appeals to engineerless engineering?

 Fruit Fly Eyes and More Surprises for Darwin

David Coppedge

Those tiny, pesky fruit flies have gotten no respect. Sprayed, swatted, and irradiated, the little flying machines have been treated by humans as better off dead. Hermann J. Muller got a 1946 Nobel Prize for blasting Drosophila melanogaster fruit flies with X-rays, finding that the barrage gave them lethal mutations. Scientists have manipulated their genes to make them grow legs out of their antennae or grow four wings, rendering them helpless. And worried farmers have convinced politicians to spray malathion over cities like Los Angeles to prevent invasions of fruit flies. But before killing off all these critters, it would be worth taking a closer look at their design.

Eyes’ Size

An adult fruit fly emerges from the egg and pupa in about two weeks. As the eyes are developing in a fruit fly embryo, an amazing process unfolds. A wave of signals sweeps across stem cells in the budding compound eye, switching on certain progenitor cells to stop proliferating and become unit eyes (ommatidia) and signaling others to undergo programmed cell death (apoptosis). The result is an “organ of extreme perfection” to call on Darwin’s phrase that is not only geometrically beautiful but functional for the fly — and it comes in matching left and right sides, like a pair of rubies.

Navarro et al. published a paper about how this works in PLOS Biology. In the same journal, Marco Milán from the Barcelona Institute of Science and Technology summarized the paper, explaining how the regulated process achieves “size precision” as the eye grows. Internal controls reduce “fluctuating asymmetry” (FA), a wobbly mismatch of size and shape. In effect, the growing cells of the eye do The Wave.

A new study unravels an organ-intrinsic mechanism of growth control in the developing fly eye that confers size precision through feedback interactions between proliferating and differentiating cells. This mechanismreduces eye size variability between and within animals, thus contributing to the symmetry between contralateral eyes and having a clear potential impact on eye functionality. In the growing eye primordium, a wave of differentiation moves anteriorly, whereby proliferative progenitors located anterior to the wave are recruited as differentiating retinal cells that exit the cell cycle (Fig 1). When the wave reaches the anterior-most region of the primordium, no remaining progenitors remain in the tissue, and the final eye size is attained. The movement of the differentiation wave relies on the activity of 2 morphogens [shape generators], the BMP homolog Dpp and Hedgehog (Hh), which are produced by differentiating retinal cells that signal anteriorly to nearby proliferating cells to recruit them as new differentiating retinal cells. 

The Barcelona team calls this “feedback control of organ size precision mediated by BMP2-regulated apoptosis.” The result is a geometrically perfect oval-shaped eye with 800 ommatidia neatly arranged like hexagonal cells on a curved honeycomb. The curved shape gives the fly greater than 180-degree visibility on each side. 

Much more must be going on, because bristles grow between each ommatidium to provide touch sensation for the fly, and each unit must be wired properly to the optic nerves going to the developing brain. What’s more, the two eyes must become exact mirror images of each other to prevent fluctuating asymmetry so that the fly can navigate with precision. The authors believe a similar process controls wing development so that the wings match. Imagine a pilot trying to maneuver a plane with one wing shorter than the other!

This one example illustrates an astonishing amount of control in an insect just a few millimeters in length. And they only investigated this in one organ — the visual system — while all the other body systems are also in the process of developing simultaneously: circulation, digestion, reproduction, muscular, flight, sensory, jointed appendages, and much more.

The authors, Navarro et al., make a logical mistake in how these controls came about:

Three features should have resulted in a strong evolutionary pressure to maximize the precision in eye size: First, size impacts vision directly, as image resolution and contrast sensitivity is proportional to the number of light sensing units in the eye; second, making and maintaining the eyes is energetically very expensive, so there is a pressure to match eye size to vision needs; and third, left and right eyes must survey a symmetrical part of the space, so eye asymmetry, which could be driven by developmental noise, should be minimized.

An unguided, blind process could not care about what “should” be done and is incapable of being pressured to do anything. Stephen Crane once quipped, “A man said to the universe: ‘Sir, I exist!’ ‘However,’ replied the universe, ‘The fact has not created in me a sense of obligation.’” Much less could molecules know about or care about “evolutionary pressure.” The authors are admittedly surprised how all these parts come together so neatly:

Biological processes are intrinsically noisy, and yet, the result of development — like the species-specific size and shape of organs — is usually remarkably precise. This precision suggests the existence of mechanisms of feedback control that ensure that deviations from a target size are minimized.

Right Flight

Here’s another fruit fly trick from recent news. How did the fruit fly make a sharp turn? This is not a joke. Sharp turns don’t just happen in a fruit fly because it has wings. They are controlled by specialized neurons. 

This month, Ros et al. published their findings in Current Biology about “Descending control and regulation of spontaneous flight turns in Drosophila.” In the same issue, Matthieu Lewis summarized the research about how and why fruit flies make sudden zigs and zags while flying.

Upon detecting an attractive odor plume, a fly surges upwind, followed by crosswind casting separated by counterturns when the plume is lost. While the sensory control of turning and casting is shared across most animals, little is known about its neural underpinnings. In a paper in this issue of Current Biology, Ros et al. report the identification and functional characterization of a pair of bistable descending neurons that orchestrate casting during flight behavior in the fly Drosophila.

These neurons, Ros et al. explain, consist of “couplets of one excitatory and one inhibitory descending cell form functional units.” As with many systems in biology and in engineering, an accelerator is paired with a brake, providing fine control with a push-and-pull combination of systems responsive to input from the surroundings. Particular “command units” of descending neurons enable a fruit fly to make sharp turns called saccades. “An array of excitatory and inhibitory neurons provides input to the saccade network,” the authors say about one of their major findings.

Within the central nervous system of insects, descending neurons (DNs) constitute a critical stage in the transformation of sensory input in the brain into motor commands in the ventral nerve cord (VNC). Drosophila possess ∼650 pairs of DNs, some of which appear to function as specialized command neurons for specific behaviors, including courtship, walking backward, turning, take-off, and landing. Thus, DNs provide a logical starting point for investigating the circuits that generate and regulate flight saccades.

Stop for a moment to picture this little millimeter-range creature containing 650 pairs of descending neurons each programmed for specific commands. One fires, and the fly walks backward. Another fires, and the fly comes in for a landing. Another fires, and boy fly courts girl fly. This sounds much more astonishing than a computer-controlled robotic drone. 

By ablating one or the other of the descending neurons (DNs) involved in saccades, the team supported their hypothesis that the couplet functions as a saccade-generating unit (SGU). 

The altered saccade dynamics and temporal distribution after ablation support the hypothesis that each DN can produce saccades independently of the other but with different dynamics than those of control flies. The results support a working hypothesis that the two DNs play complementary roles by activating different components of the motor circuit in the VNC responsible for generating saccades. Together, functional imaging, unilateral activation, and ablation experiments suggest that two pairs of descending interneurons, DNae014 and DNb01, function together as saccade-generating units (SGUs) to execute commands for spontaneous turns during flight.

Louis gives examples in other animals, from insects to mammals, that use a similar “sector search” strategy during navigation. But why would a fruit fly need to make a sharp turn?

Saccades are thought to benefit flying animals in several ways. From a sensory perspective, saccades may restrict the deleterious effects of motion blur to brief moments interjected within longer sequences of gaze stabilization. Brief bursts of saccades in the same direction may aid local search strategy by allowing the animal to quickly scan the local environment for salient visual and olfactory features. More recently, it has been suggested that comparing sensory measurements immediately before and after each saccade might enable flies to estimate key parameters that are otherwise not directly measurable, such as the direction and magnitude of the ambient wind. For all these hypotheses, the timing between saccades is critical…

Critical timing, fine control, and convergent strategies between unrelated animals — such concepts defy Darwin’s bluffing notion of the creative power of natural selection. At one point, the authors acknowledge that this looks like engineering.

The activity levels between the left and right DNae014 cells followed an inverse, highly non-linear relationship, analogous to “flip-flop” components in digital electronic circuits (Figure 1J) and reminiscent of neurons identified in the steering behavior of male silkmoths. Further, the DNb01 cells synapse directly onto contralateral DNae014 cells. This is a simple reciprocal inhibitory motif, consistent with a network responsible for binary 

More to Come

We’re not done with design in fruit flies. Next time, we will look at some of the sensory apparatus within these little insects. While fruit flies are convenient lab animals for study, undoubtedly similar systems can be found in even smaller flying insects like mosquitoes and gnats, all of which, being heavier than air, “evolved” powered flight and all their related systems because of “selection pressure.” Not.

In pursuit of a third way.

 Bad News for the “Theist on the Street”

Stephen Dilley

Is mainstream evolutionary theory compatible with a biology-based argument for intelligent design? That’s the argument of theologian Rope Kojonen’s book, The Compatibility of Evolution and Design (CED). Kojonen contends that evolution (and biology) rightly understood actually point to design. His book is perhaps the best treatment available of design and evolution from a theistic evolutionary point of view. But does it succeed?

Casey Luskin, Brian Miller, Emily Reeves, and I have published a peer-reviewed article that analyzes Kojonen’s proposal. Here I will provide an epistemological critique. We’ll see that Kojonen’s model undermines itself by raising obstacles to design detection — including the very design detection that he uses to undergird his own design argument. 

Kojonen defends the perspective of what he calls the “theist on the street” — an everyday believer in God who accepts design based on direct perception or intuition rather than a rigorous design argument. Yet it turns out that his model actually undermines such a person’s design beliefs.

The Model

We summarize his model as follows:

The details of his proposal are manyfold, but the basic idea is straightforward: the locus of design is at the origin of the cosmos (or the laws of nature) (CED, pp. 164–67). God acts at the beginning of the universe, granting to it all that is necessary for biological complexity to eventually unfold. The deity creates the laws of physics and chemistry, which then give rise to preconditions — including “the library of forms” — that enable evolution to produce complex entities. Random mutations and natural selection alone are insufficient for the emergence of biological complexity; preconditions are required, and God ultimately stands behind these preconditions (CED, pp. 97–143).1

So God designed the laws of nature, which then give rise to laws of form and other processes, which eventually produce all flora and fauna. Thus, a person who sees, say, a hummingbird for the first time can rightly intuit (or infer) that it was designed. It’s just that the locus of its design was billions of years earlier and that natural processes transmitted and unfolded this design over time.

The Problem: Part 1

What’s wrong with this picture is that it harms humans’ ability to detect design in the first place. This is for two primary reasons, which build on each other. The first is that it damages a human’s “direct design” beliefs. A “direct design” belief is a belief that a certain type of thing, like a hummingbird, was created by the immediate action of a designer rather than by mediated or secondary causes. As we explain:

In our lived experience, humans readily attribute direct design to various types of biological phenomena. (This is not only true of “theists on the street”, for example, but also of some other people as well.) For example, consider a person who sees a hummingbird for the first time. A natural reaction is to think that this type of bird was directly designed. (“Wow! That’s spectacular. Somebody made that!”) In fact, humans often experience things like hummingbirds as distinct entities — what Axe (2016, pp. 65–86, esp. 71) calls “busy wholes” or what one might call “natural kinds”. That is, humans often experience an entity like a hummingbird as a certain type of thing, and they naturally believe that this type is the result of direct design. By contrast, it is rarely the case that, upon seeing a hummingbird for the first time, a typical person would say, “Wow! That’s specular. Somebody indirectly created that by a process of secondary causes over millions of years”. Instead, many people believe that a designer directly crafted the first instance of a given specimen or feature. (“God made the first hummingbirds, then they reproduced”.) Whether rightly or wrongly, human beings routinely apprehend (or infer) direct design when they encounter the power, beauty, and complexity of organisms or organs.2

So how does Kojonen’s model affect this type of experience? Here’s how:

Yet in Kojonen’s model, these beliefs in direct design are uniformly false. In his view, there is no direct design of biological phenomena. All biological diversity and complexity are the result of indirect design. The locus of design was billions of years prior to the advent of life on Earth. (Indeed, even if Kojonen were to locate direct design at the origin of life, all subsequent flora and fauna would still be the result of indirect design.) This simply follows from Kojonen’s understanding of design (and of evolution). So, if Kojonen’s proposal were true, human beings who accepted his view would have a serious defeater for their ‘direct design’ beliefs about biological organisms and features. They would realize that they have little or no grounds to trust their minds in this context.3

So, in this model, a person would have lots of defeaters for her “direct design” beliefs about biological phenomena. 

But on what basis does Kojonen know that the laws of physics are directly designed? After all, “direct design” beliefs in biology are unreliable and, on his model, biology (alone) has sufficient evidence for design. As we explain:

[H]ow would a person in this general situation know that the laws of physics and chemistry were directlydesigned, as Kojonen believes them to be? Recall that his argument for design is supposed to be based on biological phenomena. But if his model were correct, humans would have no cases of biological things that seemed to be directly designed actually turning out to be directly designed. So, if there are no such cases — and these cases are the basis for believing that the laws of nature are directly designed — then the ground for believing that the laws are directly designed is very poor indeed. If a baseball player strikes out in his first 23 plate appearances, what basis does he have to believe that he will get a hit at his next at-bat?4

The bottom line is that Kojonen undermines his own basis for saying that the laws of physics are directly designed. If so, then he has lost his case for design. The whole point of his model is that biology provides good evidence of design even if evolutionary theory is true. But his view of biology actually undermines his view of design. Whether a person is an expert or an everyday “theist on the street,” anyone who accepts Kojonen’s model can no longer locate design where Kojonen needs it to be.

The Problem: Part 2

 A second problem, building on the first, likewise damages a human’s ability to detect design. A person who accepts Kojonen’s proposal would have significantly less ground for saying that biological phenomena provide evidence of design. This is because his model, to bring about all the flora and fauna in our world, relies on non-agent causessubsequent to the Big Bang. A non-agent cause is any cause that does not include the direct action of an agent. Most non-agent causes are physical in nature. They include, but are not limited to, evolutionary causes. Practically speaking, what does this mean?

For example, if Kojonen’s model were true, a person who accepted the model would believe that, despite her ostensible prima facie belief that, say, a designer directly crafted an eagle’s eye or the first hummingbirds, it is actually the case that each of these phenomena are proximately explained by non-agent causes. For each biological organism or feature, there would be continuity of non-agent causes from before that entity’s existence that led up to (and through) the advent of that entity. Indeed, this continuity would extend all the way back in time. (In fact, there might not be any particular reason, based in biology, to think there was a big bang.) A person who accepted this model would believe that non-agent causes gave (proximate) rise to case after case of biological complexity. The same would be true for human beings, too. An unbroken chain of non-agent causes from the ancient past would extend up to (and through) the rise of the first humans, whoever they happened to be.5

The problem is that “continuity” attenuates (or erases) evidence of design in biology. Given the continuity of non-agent causes to produce all biological phenomena, what basis is there in Kojonen’s model to say that any particular biological entity was designed? Recourse to fine-tuning in astrophysics or the Big Bang in cosmology is no help: the whole point of Kojonen’s model is that biological phenomena point to design. But if every biological entity arose from prior material causes (or non-agent) causes, on what grounds can one say that a mind was needed? Kojonen’s model destroys the detectability of design. There might still be ultimate design (at the beginning of the universe) but the evidence of design — based on biological phenomena — has been obscured.

Arguably, “mainstream” evolutionary theory — which rejects appeals to God in biology — expects strong continuity of natural causes in organic history: there’s no need to invoke God to account for the rise of any particular “kind” because natural causes are held to be sufficient. “Continuity” is just what one would expect if a non-theistic version of evolution were true — namely, that direct design beliefs are uniformly false and that, instead, natural processes appear to be capable of morphing one “kind” into another “kind” over time. Such a view is decidedly unexpected on the pre-theoretic lay theist’s default disposition toward direct design of biological kinds. Mainstream evolutionary theory pushes the theist on the street in precisely the wrong direction. Accordingly, it obscures the detectability of design for such a person. Insofar as Kojonen’s model accepts “mainstream” evolution (as he says it does), his model faces this significant epistemological difficulty.

An Eagle’s Eye

This means that Kojonen’s own biology-based design argument no longer works. After all, such an argument requires that biological design be detectable. If design cannot be detected, it cannot be parlayed into a rigorous argument. This same line of reasoning also undermines the ability of a “theist on the street” to detect design. Insofar as she accepts Kojonen’s model, she would have to regard her initial impression of direct design — of, say, an eagle’s eye — as mistaken. She’d now believe that God didn’t create the first instance directly; instead, it came about by an unbroken chain of material causes (or non-agent causes) throughout the entirety of organic history. For all that she can tell (based on biology), there is no need for recourse to a Mind. Thus, she no longer has grounds to trust her common-sense intuition of the design of the eagle’s eye — or for that matter of any other flora or fauna.     

So much for the design intuitions of everyday theists. For more on Kojonen’s book, see here

Yet more on formalizing design detection.

 

On our previleged homeworld.

 

I.D is science?: pros and cons.

 

The Ovum vs. Darwin.

 The Exquisite Design of Egg Cells

Jonathan McLatchie

In two previous articles (here and here), I discussed the irreducible complexity of sperm cells and the seminal fluid for successful fertilization. Now, I will review the exquisite design features of a female egg cell (also called an ovum, plural ova). Here is an animation of the incredible process of reproduction, from ejaculation to birth.

Oogenesis

Oogenesis (the process of egg cell formation) begins during embryonic development when the primordial germ cells are specified. These cells migrate to the genital ridges, which later develop into the female ovaries. Prior to birth, the primordial germ cells undergo mitotic divisions to form oogonia, the precursor cells for eggs. These oogonia transform into primary oocytes, which are diploid cells arrested in prophase I of meiosis. This arrest typically occurs before or shortly following birth.

Primary oocytes are surrounded by somatic cells to form primordial follicles, which go through a process called folliculogenesis, where they develop into primary, secondary and eventually tertiary follicles. As a female reaches sexual maturity, some primary oocytes are activated each menstrual cycle. The activated primary oocyte completes meiotic division I, resulting in the formation of a secondary oocyte and a smaller cell called a polar body (the primary purpose of the polar body is to discard the extra genetic material that is produced during meiosis). However, the secondary oocyte is arrested in metaphase II. 

The mature follicle ruptures during ovulation, releasing the secondary oocyte into the fallopian tube. If fertilized by a sperm cell, the secondary oocyte completes meiotic division II, resulting in a mature egg (ovum) and another polar body. If fertilization does not occur, meiosis II is not completed. After ovulation, the remaining follicle transforms into the corpus luteum, which secretes hormones like progesterone to prepare the uterus for a potential pregnancy. If fertilization doesn’t happen, the corpus luteum degenerates, resulting in a drop in hormone levels. This triggers menstruation, and the cycle resets.

Fertilization

As I discussed previously, sperm cells swim through the female reproductive tract, directed by the cilia, in addition to chemical signals. Chemicals called chemoattractants are released by the egg cell, and these serve as signaling molecules that generate a concentration gradient. The sperm cell is capable of chemotaxis, a process that results in the sperm cell moving up the concentration gradient, towards higher chemoattractant concentrations. Changes in chemoattractant concentration are detected by specialized receptors on the surface of sperm cells. When an increase in concentration is detected, a signaling cascade is triggered within the cell, which influences the flagellum’s beating pattern. Thus, the sperm moves progressively in the direction of the egg — that is, the source of the chemoattractants. As the sperm swims towards the egg, the concentration of chemoattractants is continuously being measured, which allows it to adjust its course in order to fine-tune its movements. Once the sperm gets within close proximity of the egg, it encounters other signaling molecules that further guide the sperm cells and direct it towards the egg’s plasma membrane, the site of fertilization.

Upon reaching the egg, the sperm cell encounters the zona pellucida, a glycoprotein rich matrix that surrounds the egg. Sperm-egg recognition begins with the interaction between glycoproteins on both the sperm surface and zona pellucida, thereby guiding the sperm cell towards the egg cell’s surface.

In a previous article, I wrote about the acrosome, a specialized structure possessed by sperm cells, that contains enzymes that aid in penetrating the egg’s protective barriers. Contact between the sperm and the zona pellucida results in the acrosome undergoing exocytosis, releasing these enzymes. These enzymes help to create a pathway for the sperm to arrive at the plasma membrane of the egg. Once through, fusion occurs between the egg and the sperm’s plasma membrane, thereby allowing the sperm’s genetic material to come into proximity with the egg’s cytoplasm.

Egg Activation

Upon fusion of the plasma membranes of the sperm and egg, various changes are triggered in the egg, collectively referred to as “egg activation.” First, the egg’s membrane becomes less permeable to other sperm, in order to prevent a single egg from being fertilized by more than one sperm cell. The fast block to polyspermy involves a change in the electrical properties of the egg’s plasma membrane. When the sperm’s outer layers are successfully penetrated by the sperm cell, it triggers the release of calcium ions (Ca2+) from intracellular stores in the egg.

The influx of calcium ions serves as a signal to initiate changes in the egg’s membrane potential. Ion channels on the egg’s membrane are opened, and facilitate the entry of sodium ions (Na+). The consequence is that the egg’s plasma membrane depolarizes. Normally, the egg’s membrane is maintained at a negative resting potential. However, the influx of positive sodium ions neutralizes this negative potential, making the membrane potential less negative. The altered membrane potential makes it more difficult for other sperm to initiate the fusion process, and thereby creates a temporary electrical barrier that inhibits additional sperm from fusing with the egg. The depolarization is a temporary phenomenon. After a brief period, the egg membrane potential is restored to its normal resting state (often referred to as “resetting” the egg).

A secondary defense against polyspermy is known as the slow block, or the “cortical reaction.” As calcium ions are released upon fertilization, this triggers the exocytosis of cortical granules, located just beneath the egg’s plasma membrane, containing enzymes. The glycoproteins in the zona pellucida are cross-linked by these enzymes, and this results in the hardening of the zona pellucida, reducing its permeability. The modified zona pellucida forms a structure called the “fertilization envelope,” which surrounds the egg, forming a barrier that physically blocks additional sperm from gaining access to the egg’s surface.

Changes also take place in the egg cell that promote the completion of meiosis and initiate early embryonic development. The genetic material of the sperm and egg, consisting of a single set of chromosomes each (23 chromosomes in humans), combine to form a diploid cell called the zygote, which contains the full set of chromosomes needed to develop a new individual. This instantly determines gender, eye and hair color, and many other traits.

After fertilization has occurred, the zygote begins to undergo a series of rapid cell divisions through a process called cleavage. This results in the development of a multicellular embryo, which travels through the fallopian tube towards the uterus. Eventually, it arrives at the uterus and attaches to the uterine lining in a process called implantation.

An Exquisite Design

As one can see from the foregoing discussion, the development of an egg cell and its activation in response to encountering a sperm cell exhibit exquisite design, being contingent upon multiple mutually dependent processes, all of which are needed for successful reproduction. When considered in conjunction with the incredible engineering features of the sperm cell and the seminal fluid (discussed in a previous articles), it would seem to put the thesis of design almost beyond question

Newly revealed evidence for ID

 Hidden, Now Revealed: Amazonia, Fitness Landscapes, and Fibonacci Numbers

David Coppedge

Here are some news items of interest for those who have followed my previous articles about Amazonia, fitness landscapes, and Fibonacci numbers. They are united by the theme of “hidden” things now revealed.

Hidden Cities in the Jungle

In 2022 (here), I shared news about “mind blowing” discoveries made with LIDAR (Light Detection and Ranging) in the Amazon rainforest. The forest-penetrating technology uncovered “geoglyphs” (large structures) that were made by previously unknown people groups. Last fall (here) I updated the story with new estimates that there might be many thousands more to discover. This was a classic test of The Design Inference: eliminating chance by specified complexity and small probability.

Since then, a “huge ancient city” has been revealed by LIDAR, reports BBC News, and was explored by ground crews. Some 6,000 mounds are at the large site, probably foundations for homes. 

“It changes the way we see Amazonian cultures. Most people picture small groups, probably naked, living in huts and clearing land — this shows ancient people lived in complicated urban societies,” says co-author Antoine Dorison.

The city was built around 2,500 years ago, and people lived there for up to 1,000 years, according to archaeologists.

It is difficult to accurately estimate how many people lived there at any one time, but scientists say it is certainly in the 10,000s if not 100,000s. 

See New Scientist’s article on this find, with a LIDAR scan of the extensive site. It adds,

In 2015, Rostain’s team did an aerial survey with lidar, a laser scanning technique that can create a detailed 3D map of the surface beneath most vegetation, revealing features not normally visible to us. The findings, which have only now been published, show that the settlements were far more extensive than anyone realised….

The survey also revealed a network of straight roads created by digging out soil and piling it on the sides. The longest extends for at least 25 kilometres, but might continue beyond the area that was surveyed.

This month, Jay Silverstein, an archaeologist renowned for the detection of hidden artifacts in Amazonia and elsewhere, wrote in The Conversation about these amazing discoveries. The title of his essay promises big news ahead, “Valley of lost cities found in the Amazon — technological advances in archaeology are only the beginning of discovery.”

A valley of lost cities has been discovered in the Ecuadorian Amazon. When you hear of such a discovery you might think of archaeologists with chisels and brushes or explorers in pith helmets stumbling across sites deep in the forest. Instead, without needing to brave the hazards of the forest, Light Detection and Ranging (Lidar) has revealed networks of buried roads and earthen mounds.

The point of exploratory science is to reveal what has so far been hidden. Whether at the edge of the universe with the James Webb Space Telescope (JWST), the bottom of the sea with Underwater Autonomous Vehicles (UAVs), or through the canopy of the densest forests with Lidar, we are discovering things that reshape our understanding of the world. 

It’s like finding the key to a cryptogram, or the figures in a stereogram, to see these city-scale structures under the forest canopy for the first time. Silverstein believes that scientists are nowhere near running out of things to discover. LIDAR and aerial search systems have revolutionized archaeology, but there will always be a need for ground-based searches and excavations — meaning, there will continue to be ample opportunities for design detection. (This is not to imply that design in the forest leaves, loaded with ATP synthase motors, does not warrant its own design inference.)

Hidden Assumptions in the Fitness Landscape

Like letters crossing in the mail, scientific papers can contradict one another. The authors of a paper in Oxford’s International Journal of Organic Evolution, blithely assuming there is wisdom in Wright’s “fitness landscape” metaphor, were apparently unaware of the PNAS paper the previous month that debunked it (see my post on that paper here). True, authors can innocently miss others’ work due to lag times between research, writing, and publication, even if they do a literature search, but this points to a problem in peer-reviewed scientific publications: wrong notions can persist even after they have been falsified.

The Oxford Evolution paper, “The fitness landscape of a community of Darwin’s finches,” by 18 authors, builds its case on the notion of a Gaussian landscape, not realizing that the landscape is flat with trapdoors (according to the PNAS authors), and that “holey landscapes” represent “the dominant evolutionary process.” 

The drivers of adaptive radiation have often been conceptualized through the concept of “adaptive landscapes,” yet formal empirical estimates of adaptive landscapes for natural adaptive radiations have proven elusive. Here, we use a 17-year dataset of Darwin’s ground finches (Geospiza spp.) at an intensively studied site on Santa Cruz (Galápagos) to estimate individual apparent lifespan in relation to beak traits.

Onward they go, eager to perpetuate this icon of evolution that Jonathan Wells debunked 24 years ago. Now, with the collapse of Wright’s “fitness landscape” metaphor (at least the smooth Gaussian kind with curving hills and valleys), their work has been doubly debunked. It’s kind of sad. They mention fitness peaks 90 times, fitness valleys 16 times, landscape 154 times, and “fitness” 194 times. It would be one thing if they argued that Dochtermann et al. were wrong in their assessment of the landscape metaphor being “holey” in their PNAS paper, but these authors seem oblivious to the problem that composite traits cannot gain fitness on a flat landscape. They can only disappear through one of the trapdoors.

One can only wonder how long it will take for the landscape myth — organisms gradually ascending to higher fitness by natural selection — to collapse. Since the “fitness landscape” metaphor has been extremely useful to Darwinians, as in this new paper, it is likely to continue as a useful lie for some time. Perhaps Dr. Wells can use it as another case of Zombie Science.

Hidden Glories in the Infrared

The James Webb Space Telescope Mission Team revealed a blockbuster set of images at the end of January: a catalog of spiral galaxies displayed in exquisite detail. Adding to the splendor of the gallery, NASA scientists combined images from the Hubble Space Telescope and data from other instruments, including the “the Very Large Telescope’s Multi-Unit Spectroscopic Explorer, and the Atacama Large Millimeter/submillimeter Array, including observations in ultraviolet, visible, and radio light.” The combined data sets provided a multicolored, high-resolution gallery of images that is sure to tantalize astronomers and delight the public.

The caption for one image of spiral galaxy NGC 628 (pictured at the top) includes this note: “The spiraling filamentary structure looks somewhat like a cross section of a nautilus shell.” This recalls posts here at Evolution News about the uncanny ubiquity of phenomena exhibiting the Fibonacci series (here, here, here, here, here). Why should a nautilus shell mimic the structure of a spiral galaxy differing in size by many orders of magnitude? As I remarked in this link, the question remains unanswered in spite of modelers’ attempts to explain one example in plant stems.

The formalizing of design detection and the case for ID

 

The role of maths in formalising design detection.

 

Re:the genome's on/off switches.

 

Yet more re:the God hypothesis.

 Andrew Klavan and Stephen Meyer Talk God and Science

Evolution news

On a classic episode of ID the Future, philosopher of science Dr. Stephen C. Meyer sits down with talk show host and bestselling novelist Andrew Klavan to discuss Meyer’s Return of the God hypothesis. In this fast-paced conversation the pair touch on the Judeo-Christian roots of science, how fine-tuning in physics and cosmology point to intelligent design, and how a great many scientists held out hope that the universe was eternal and therefore did not require a creator, until the evidence for a cosmic beginning mounted. What about the multiverse hypothesis as an escape for atheists wishing to explain away the evidence for a cosmic designer? Meyer explains why it fails the test of Occam’s razor. Finally, Meyer and Klavan discuss a noted atheist philosopher who frankly admits that he doesn’t want theism to be true and yet also admits that modern Darwinism has failed and that the evidence for design in various scientific fields is too powerful to be ignored. 

Download the podcast or listen to it here. 

On the ingenious design of trees.

 Paper Digest: Are Trees Well Designed?

Emily Reeves

Editor’s note: Evolution News is delighted to continue an occasional series, “Paper Digest,” looking back at past publications in peer-reviewed journals of interest in the debate about intelligent design.

Back in 2004 in the Journal of Engineering Design, Stuart Burgess, a longtime proponent of intelligent design theory, and D. Pasini Published on the physics and design principles of trees. Specifically, the study looks at the mass-efficiency of the structural shapes and forms found in trees. Burgess and Pasini explain that their purpose is “to understand how high levels of mass-efficiency are achieved [in trees] and to identify lessons for engineering designers.”

Consistent with Burgess’s general research strategy — using the assumption of good design in nature to guide investigation, further scientific knowledge, and better elucidate how natural systems work — this paper is an excellent example of how ID research can be applied in a scientific discipline.

A Key Step in Reverse Engineering.

To classify the function of structural features of a tree, Burgess and Pasini use a methodology called a function-means tree. This is just a graphical way of identifying a hierarchy of functions, beginning with the highest and then depicting how these are fulfilled by lower-level functions. Building this hierarchy of objectives is a very important step in reverse engineering because it helps one to understand the functional reasons for structures observed in nature.

Major Sources of Load

To appreciate the design of a tree, Burgess and Pasini explain that it is important to understand the major sources of loading or forces that a tree must endure. These loads come from the wind and the weight of the tree itself. Using their engineering toolset, Burgess and Pasini offer equations to estimate the aerodynamic force due to the wind, the bending of the trunk, and the maximum stress the tree endures. From these equations, they discover the engineering importance of a tree’s structural design features, such as a tapered trunk and the structural hierarchy of little branches being supported by bigger branches. They also discover fun facts like large trees don’t have greater bending stress than small ones, but taller trees might have greater bending stress due to higher wind speeds further up from the ground. They authors are also able to determine some of the fail points and they note that for storms with winds of greater than 100 mph, trunks and branches are very vulnerable to breaking.

Next, Burgess and Pasini discuss the self-weight of the tree trunk and note that the compressive stress is not significant even for large trees because of their structure. Since trees grow straight up and then have branches emerging from all sides, much of the bending stress is alleviated through this excellent design of counterbalance.

Burgess and Pasini mention that one of the most important things about the overall structure of the tree is its structural hierarchy. There is first the trunk, then the main branches, then the secondary branches, and finally the tertiary branches and leaves. This hierarchy provides several advantages. First, it allows the surface area of the tree’s canopy to be linked to its source efficiently. The hierarchy also allows a relatively direct load path from the canopy to the trunk. Finally, the hierarchy mediates the ability for gradual growth. Through their expertise and with the help of a design lens, the authors can reverse engineer and understand the structural design of trees

Structural Features of the Trunk and Main Branches

Key structural features in the trunk include tapering and residual stresses. Tapering is the effect of the top of the trunk having a smaller diameter than the bottom of the trunk. Burgess and Pasini explain that this is a good design because the maximum bending varies the least at the bottom and the most at the top. It also reduces the amount of biomass that the tree must produce. The design of the trunk to bend also enables pre-stressing. This helps to improve the tree’s strength by relieving stress a little at a time instead of all at once in a devastating snap. They explain

When the tree is subjected to aerodynamic loading, bending stresses are superimposed on the residual tensile stresses. Pre-stressing is a beneficial structural feature because when the trunk is subjected to bending moments, the net compressive stresses are less than the net tensile stresses. Since the compressive strength of wood is lower than the tensile strength, the preloading significantly improves the strength of the tree.

Major branches connect the smaller branches to the trunk of the tree, which means they are subject to large loads because of the number of small branches and leaves attached. Burgess and Pasini note that, to compensate, the main branches, just like the trunk, are tapered — with the greatest diameter near the trunk, and tapering to a point. With major branches, the diameter of the branch changes from circular to rectangular, and the depth, especially at the connection point, is increased to support increased load bearing as the branch supports more and more weight.

How Leaves Minimize Aerodynamic Loading

Burgess and Pasini explain that in engineering, designs are often optimized around either strength or stiffness. When optimizing a design for strength, more flexibility is possible because stiffness is not a strict requirement. The authors observe that trees seem to be structurally designed more for strength. This is especially clear when we look at the smaller branches of a tree and its leaves, which readily deform in the wind, thereby minimizing aerodynamic loading. Despite their extreme flexibility, the design of the leaves still keeps them stable enough to provide a flat surface for light collection. In engineering, this is called high bending stiffness but low torsional stiffness.

The Structural Role of Roots

Hold-down bolts in concrete, connecting a building to its foundation, are comparable to sinker roots, a type of root that grows deep into the soil. Unlike hold-down bolts, though, roots are multifunctional, providing not only structural support but also water uptake. Burgess and Pasini explain that the lateral roots extend perpendicular to the sinker roots and provide an anchoring system through the creation of a plate of soil to which the tree structure is bound. For some trees with high growth rates, buttresses provide additional support as the underground root systems develop more slowly than canopy growth.

The Amazing Design of Wood’s 

Microstructure

Burgess and Pasini briefly discuss the incredible design of wood’s microstructure, which is that of hollow cells with a hexagonal shape. They explain that being hollow reduces the overall density of wood, which reduces the load needed to be borne by the trunk and branches. They also derive an equation for a performance factor, demonstrating how the hexagonal microstructure strengthens the structure significantly.

Inspiration for Engineers

In this publication, Burgess and Pasini describe how trees are incredibly well-designed to withstand the forces of their own weight and the wind. Trees have smart structural design features like a multilayered hierarchy, counterbalance of loads, tapering to preserve resources, flexibility for minimal aerodynamic loading, and an appropriate microstructure. The authors note the structural efficiency of the tree is essential to its survival and ability to fulfill its roles in the ecosystem. Interestingly, engineers use nearly all the structural aspects of trees, but trees still have more multifunctionality than is commonly seen in human engineering. Burgess and Pasini conclude by looking forward, with the expectation that trees still offer additional sources of inspiration for engineers, especially when it comes to “multi-functioning structures with smart, adaptable behavior.”

Still yet more on why ID is already mainstream

 

An example of non darwinian design?

 

You should listen to your gut?

 New Findings About Our Mysterious “Second Brain”

Denyse O Leary

It wasn’t long ago that researchers were hardly aware of the way the digestive system functions as a second brain. The big focus was neurons. But, along with neurons, both the central nervous system and the digestive system make extensive use of glial cells, whose function has not been as well understood.

Glial cells, which do not produce electrical impulses, were considered “electrophysiologically boring.” We now know that they support neurons in both physical and chemical ways. In the gut, they co-ordinate immune responses. From the Francis Crick Institute, we learn:

… the enteric nervous system is remarkably independent: Intestines could carry out many of their regular duties even if they somehow became disconnected from the central nervous system. And the number of specialized nervous system cells, namely neurons and glia, that live in a person’s gut is roughly equivalent to the number found in a cat’s brain.

MOHAMMAD M. AHMADZAI, LUISA SEGUELLA, BRIAN D. GULBRANSEN. CIRCUIT-SPECIFIC ENTERIC GLIA REGULATE INTESTINAL MOTOR NEUROCIRCUITS. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES, 2021; 118 (40): E2025938118 DOI: 10.1073/PNAS.2025938118 THE PAPER IS OPEN ACCESS.

Researcher Brian D. Gulbransen explains, “In computing language, the glia would be the logic gates. Or, for a more musical metaphor, the glia aren’t carrying the notes played on an electric guitar, they’re the pedals and amplifiers modulating the tone and volume of those notes.”

Understanding how much the digestive system functions, in part, as its own brain may help researchers develop better treatment for the gut disorders that afflict about 60 to 70 million people in the United States alone.

The Role Microbes Play

The vagus nerve is a stout cable of neurons that serves as an information highway between the base of the brain and the gut. Even though it is the longest nervous system connection in the body, messages take only milliseconds to travel between the brain and the gut.

The really surprising thing is that the trillions of microbes that inhabit a human digestive system play a role in all these communications, as University of British Columbia neuroscientist Heather Gerrie notes:

Many of these microbes live in the mucus layer that lines the intestines, placing them in direct contact with nerve and immune cells, which are the major information gathering systems of our bodies. This location also primes microbes to listen in as the brain signals stress, anxiety or even happiness along the vagus nerve.

But the microbes in our gut microbiome don’t just listen. These cells produce modulating signals that send information back up to the brain. In fact, 90% of the neurons in the vagus nerve are actually carrying information from the gut to the brain, not the other way around. This means the signals generated in the gut can massively influence the brain.

HEATHER GERRIE, “OUR SECOND BRAIN: MORE THAN A GUT FEELING,” UNIVERSITY OF BRITISH COLUMBIA GRADUATE PROGRAM IN NEUROSCIENCE.

A Constant Battle

Another of the remarkable qualities of glial cells is that they can shift from one type to another, as needed, in the constant battle to keep pathogens and toxins at bay.

As Yasemin Saplakoglu points out at Wired,

… scientists now know that enteric glia are among the first responders to injury or inflammation in gut tissue. They help maintain the gut’s barrier to keep toxins out. They mediate the contractions of the gut that allow food to flow through the digestive tract. Glia regulate stem cells in the gut’s outer layer, and are critical for tissue regeneration. They chat with the microbiome, neurons, and immune-system cells, managing and coordinating their functions.

YASEMIN SAPLAKOGLU, “UNPICKING THE MYSTERY OF THE BODY’S ‘SECOND BRAIN,’” WIRED, JANUARY 14, 2024

This “chat” among neurons, glia, and microbes could be important for research into the digestive system in relation to mood disorders and anxiety and depression. People often assume that their stomachs are upset because they are emotionally upset. But the story of the millions of communications shunted back and forth in milliseconds could be more complicated than that.

As Jay Pasricha, M.D., director of the Johns Hopkins Center for Neurogastroenterology, says,“The enteric nervous system doesn’t seem capable of thought as we know it, but it communicates back and forth with our big brain — with profound results.”