echolocation

Echolocation…Solved?

We have seen that a new evolution book co-authored by evolutionist Dennis Venema, Adam and the Genome, is influenced by the mythical Warfare Thesis (here and here) and makes erroneous arguments that the fossil evidence supports evolution (here). Regarding the Warfare Thesis the book propagates the false history that the basic issue of the 17th-century Galileo Affair was “the veracity of the new science, and its perceived threat to biblical authority.” As we saw, this is the false, evolutionary rendition of history. The Warfare Thesis is a myth, and the Galileo Affair is perhaps the favorite example for evolutionists.

Regarding the fossil evidence (which reveals species appearing abruptly in the strata), the book makes two erroneous arguments: that evolution is needed for science to work at all (the “intellectual necessity” philosophical argument) and the use of random design as the alternative to evolution (a theological argument).

Now we move on to another topic: echolocation. This was of particular interest to me since I have used echolocation as an example of how evolution fails. When I saw that Venema appealed to echolocation to argue for evolution I was keen to see what he had to say. I am always looking for good arguments for evolution, but I did not find one here. Below I summarize the five different reasons why echolocation destroys evolution. Finally, I turn to Venema’s argument, if it can be called that. What we will see is that his argument utterly fails. Venema fails to address any of the problems with echolocation, and he fails to present any kind of a positive case that might be used to overcome the many problems.

Complexity: The Original Sonar Technology

Most people are familiar with the concept of radar and sonar. Simply put, a reflected signal is used to track a target. But what most people are less familiar with are the many details and complications any radar or sonar system must reckon with. For example, the transmitted pulse must be very strong because it will weaken as the square of the distance it travels, and only a tiny fraction of it will be reflected. Ultimately, the return signal is very weak, so while the receiver is exposed to the very powerful transmitted signal, it must then detect a return signal many orders of magnitude weaker. Think of shouting as loud as you can, and then listening for the echo off of a mosquito.

This is just the beginning of the many sonar design issues. The pulse rate, duration, intensity, pitch are all design parameters that influence how small a target can be detected, how far away it can be detected, how accurately it can be tracked and resolved, and so forth. An advanced sonar design can vary these parameters to optimize the tracking.

Sonar design must also consider how to compensate for target motion and the resulting Doppler effect, erroneous reflections from clutter in the environment, and how to guide toward a moving target. There is also the possibility of imaging to determine what type of target it is.

Not surprisingly, there are many different sonar design strategies. Depending on the clutter environment, typical types of targets, and so forth, various design strategies might work better.

All of this is what we find in nature’s echolocation designs. Whales and bats have incredibly efficient and accurate tracking capabilities. We have developed sonar, but nature had it all along — the original sonar technology. In fact nature’s designs are better than our military equipment. Which is one reason why they are studied so closely.

Complexity at the Molecular Level

We have seen how complicated echolocation can be. Not surprisingly, the molecular machines that help to make it happen are also highly complex. Prestin, a protein important in mammalian hearing, is a transmembrane protein in the outer hair cells of the cochlea. It serves as a frequency-selective amplifier in a sound system that works something like this.

As sound enters the ear, it deflects the outer hair causing tiny amounts of stretching or compression in the outer hair cells. There are channel proteins that sit in the membrane of these cells which are sensitive to such mechanical strain. These proteins provide a tunnel (or channel) across the membrane so that ions can easily cross, and the mechanical strain can cause the channels to open.

These channels are precisely designed to allow only certain types of ions to cross. For example, some channels allow the positively charged potassium ion to cross but not the positively charged sodium ion, and vice-versa.

When a channel opens, ions usually tend to cross through the membrane (either into the cell or out of the cell) because the ion concentration is not uniform, and because there is a voltage, across the membrane. Such differences in concentrations across the membrane, and the voltage, are actively maintained by the cell. They serve as a sort of battery whose energy can be tapped at any time by opening membrane channels.

When the incoming sound causes certain channels to open, the ions that cross cause a change in the membrane voltage. In the outer hair cells, this voltage change encourages negatively charged chlorine ions to exit the cell. They interact with the prestin protein, in the membrane, to cause a mechanical deformation resulting in the elongation of the cell.

In other words, the incoming sound, that caused the hair to move, ends up causing yet more hair movement, and this serves precisely to amplify the incoming sound. This amplification is greater at low sound levels, as it should be.

One of the interesting features of this system is the speed at which it operates. Obviously, in order to amplify sound you need to respond as fast as the changes in sound occur. Protein motors often use chemical energy (such as the splitting of the ATP molecule) but that would be too slow for the ear’s sound system. Instead, prestin uses the membrane’s voltage. This electrical energy can be used much faster and prestin operates at microsecond rates. Here is how one paper summarized the system:

The exquisitely high sensitivity and frequency selectivity of the mammalian hearing organ originates from a mechanical amplification mechanism that resides in the organ of Corti, the sense organ of hearing in mammals. The gain provided by this amplification can reach as high as a thousandfold; it is highest at low sound levels and progressively diminishes with increasing sound energy.

Evolution has no explanation for the origin of this system beyond unfounded speculation, and this is only the beginning of the many molecular machines behind the echolocation systems found in nature.

Echolocation Designs Incongruent with Evolutionary Tree

It does not appear that random mutations are the cause of systems such as echolocation in bats and whales. Although this is an enormous problem for evolutionary theory, it is not the only one. As discussed above, there are many different types of echolocation designs. Evolution would predict that species that are thought to be close neighbors on the evolutionary tree would share similar echolocation designs. In other words, the echolocation designs should be congruent with the evolutionary tree. But they are not.

Whereas Darwin argued that the evolutionary tree explained nature’s designs rather than habitat, nature’s echolocation designs follow the exact opposite rule. Here is how one paper described it:

the animal’s habitat is often more important in shaping its call design than is its evolutionary history.

This is an enormous falsification of a key prediction of evolutionary theory.

Convergence at the Morphological Level

One consequence of this falsification is that evolutionists must construct highly complicated narratives for the origin of echolocation. For example, if evolution is true, then we must believe that the incredible echolocation ability found in some bats arose multiple times, by evolving independently. That’s not easy for evolutionists to explain. How could such uncanny design details repeat themselves via blind biological variation (no, natural selection doesn’t help)?

But this convergence problem goes far beyond the bats. Whales and bats share some uncanny similarities in how they track their prey. But if evolution is true, we would have to believe that their common ancestor had none of these capabilities. So in completely different parts of the world, in completely different environments, random mutations in these different species must have independently constructed the same ultra complex designs. As one report explained:

Though they evolved separately over millions of years in different worlds of darkness, bats and toothed whales use surprisingly similar acoustic behavior to locate, track, and capture prey using echolocation, the biological equivalent of sonar. Now a team of Danish researchers has shown that the acoustic behavior of these two types of animals while hunting is eerily similar.

If evolution is true then bats and whales would have been evolving independently for millions of years. And yet they both constructed a sonar capability which involves transmitting loud signals while receiving incredibly weak signals, adjusting the signal parameters in real time, processing the received signals, and so forth. They even share the same range of ultrasonic frequencies:

Bats and toothed whales (which include dolphins and porpoises) had many opportunities to evolve echolocation techniques that differ from each other, since their nearest common ancestor was incapable of echolocation. Nevertheless — as scientists have known for years — bats and toothed whales rely on the same range of ultrasonic frequencies, between 15 to 200 kilohertz, to hunt their prey.

And that similarity is in spite of the different environments:

This overlap in frequencies is surprising because sound travels about five times faster in water than in air, giving toothed whales an order of magnitude more time than bats to make a choice about whether to intercept a potential meal.

But that is not all. The bat and whale also use similar strategies for adjusting their signals while homing in on prey:

Bats increase the number of calls per second (what researchers call a “buzz rate”) while in pursuit of prey. Whales were thought to maintain a steady rate of calls or clicks no matter how far they were from a target. But the new research shows that wild whales also increase their rate of calls or clicks during a kill — and that whales’ buzz rates are nearly identical to that of bats, at about 500 calls or clicks per second.

It is another example of a complex design evolution can only speculate about, and once again the evolutionary tree fails to predict its pattern.

Convergence at the Molecular Level

Not only is incredible echolocation convergence evident at the morphological level, it is also seen at the molecular level. For instance, the prestin proteins in certain bat and whale species are more similar than evolution would expect. The massive prestin protein has too many amino acids that match up between these species. If one were to construct an evolutionary tree on the basis of prestin comparisons alone, then the bat and whale would be grouped together, and that cannot be correct.

This fact alone need not be a problem for evolutionists. They simply say that prestin is under the influence of strong selection. In other words, there are strong functional constraints on prestin that require more similarity, even between distant species, than we typically find in proteins.

In particular, researchers identified nine amino acids in prestin that seem to be responsible for the overly-consistent whale-bat matchup. Those nine amino acids must be under very strong selection. If one of them mutated then the biosonar system would not work well. The bat or whale would not survive, and that is why we don’t observe such changes. That is how natural selection works.

But if all nine amino acids are required, how did evolution stumble onto the design in the first place? It would be highly unlikely for the right nine amino acids to arise via blind mutations, at the same time.

But the convergence of molecular machines behind echolocation goes far beyond prestin. As one paper explains, “convergence is not a rare process restricted to several loci but is instead widespread.”

As one evolutionist admitted, “These results imply that convergent molecular evolution is much more widespread than previously recognized.” And another conceded that the results are astonishing:

We had expected to find identical changes in maybe a dozen or so genes but to see nearly 200 is incredible. We know natural selection is a potent driver of gene sequence evolution, but identifying so many examples where it produces nearly identical results in the genetic sequences of totally unrelated animals is astonishing.

Astonishing.

Venema: Why Echolocation Is Not a Problem

This brings us to Venema’s argument for why echolocation is not a problem. Given the enormous difficulties briefly reviewed above, how exactly does Venema find echolocation to be evolution-friendly? We have looked at the problem of complexity of echolocation, including at the molecular level, the problem that echolocation designs are incongruent with the evolutionary tree, and, as an example, the problem of convergence at both the morphological and molecular levels. Surely no objective scientist would find evidence for evolution in nature’s echolocation designs.

Would they? Believe it or not, here is what Venema writes:

If you’ve ever stumbled through a pitch-black room and pulled yourself up short just before colliding with a wall or other object, you have employed your (very rudimentary) sense of echolocation. What you detected (though you might not have even consciously perceived it) was that sound waves were reflecting off the object in your way. All mammals can do this, but most (like us) do it very poorly. We need to be very close to the object in question before it is even possible for us to notice reflected sound, and more likely than not we won’t, and we’ll stub our toe or worse.

As it turns out, cetacean echolocation is a specifically tuned sense of hearing that is based on the same genes used for hearing in other mammals. One key gene used for hearing in all mammals is called the “prestin” gene, a protein involved with the specialized structures in the mammalian ear that vibrate in response to sound waves. In whales, the prestin gene is tuned to the ultrasonic frequencies that are better suited to echolocation. This tuning required only a few amino acid changes within the protein — an amount of change easily within the reach of the sort of molecular tinkering we saw for the insulin gene in various mammals. This tinkering within the prestin gene to tune it for echolocation was so easy to achieve, it would seem, that nearly identical changes occurred independently in the lineage leading to modern bats, who also use a prestin tuned to ultrasonic frequencies for echolocation. So even echolocation is not “new” — it too is remodeled from a standard mammalian sense of hearing.

This is a complete disaster. Venema’s equating of echolocation with his imagined ability to avoid a wall in a dark room, his transforming convergence to a virtue, his casting of echolocation as “easy to achieve,” the result of mere “tinkering,” and nothing new but rather simply a remodel of “standard mammalian sense of hearing,” is all standard evolutionary pretzel logic.

This is the evolutionary “just add water” view of biology where you add a couple of mutations and, poof, you have echolocation. But as we saw above, echolocation is not at all comparable to “standard mammalian” hearing. It doesn’t fit the evolutionary tree, and the convergence is astonishing and utterly unexpected and unexplained.

Venema’s attempt to explain away echolocation as a standard result of evolution is not even wrong.

I have followed the echolocation research for years. I write about it, and often include it in presentations. I discuss the various ways the echolocation evidence contradicts evolution. So why would there be a section on this subject in this book promoting evolution? Have I missed something? Is there some fundamental aspect of echolocation I have missed? Is there a new paper I have missed, overturning the large body of research?

No, as I read the section, I quickly realized it was nothing more than the usual evolutionary just-so story. A wholesale ignoring of well-established science, an embracing of imagined thought experiments that make no sense, and an utterly unscientific conclusion.

Photo: Egyptian fruit bat, by Mickey Samuni-Blank (Own work) [CC BY-SA 3.0], via Wikimedia Commons.

Source: Echolocation…Solved? | Evolution News

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