Yesterday, I came across a fascinating article on hearing in whales and dolphins that blew my mind away, entitled, A New Acoustic Portal into the Odontocete Ear and Vibrational Analysis of the Tympanoperiotic Complex by T.W. Cranford, P. Krysl and M. Amundin (PLoS ONE 5(8): e11927, 2010, doi:10.1371/journal.pone.0011927). Odontocetes, for those who may be wondering, are commonly known as toothed whales – a category that includes porpoises and dolphins. And the tympanoperiotic complex is the so-called “ear-bone” of whales, porpoises and dolphins (see here for a more technical definition).
The article revealed that hearing in whales and dolphins is a staggeringly complex process, which scientists are still struggling to understand.
There is an old Chinese proverb that a picture is worth a thousand words. I’d like to show my readers five pictures from the article cited above, and let them form their own conclusions.
My first picture depicts the anatomy around the right tympanoperiotic complex – the so-called “ear-bone” of whales – in the killer whale, Orcinus orca. Readers can view it by clicking here. I would invite readers to enlarge the image, in order to get a good view of the parts and how they work together.
My second picture is even more amazing. It depicts the left tympanoperiotic complex (or “ear-bone”) of the Pacific white-sided dolphin, Lagenorhynchus obliquidens. Readers can view it by clicking here. No less than fifteen different parts are shown.
My third picture shows a view from inside the tympanic cavity of the same dolphin. Readers can view it here. The detail of the tiny parts is astounding.
My fourth picture contains a stunning view of the left tympanoperiotic complex (or “ear-bone”) of the common bottlenose dolphin, Tursiops truncatus. Readers can view it here. In addition to showing the cochlear spiral and semicircular canals, it also shows the cochlear nerve, all contained within the periotic bone.
My fifth picture depicts an inverted view of the TPC (or “ear-bone”) of the common bottlenose dolphin, vibrating at a frequency of 146.4 kHz. The dolphin’s ear vibrates in a very distinctive way for hundreds of different frequencies. Readers can view an animated GIF of the ear-bone vibrating at 146.4 kHz by clicking here. Because the frequency is very high, this animated GIF shows the most extreme twisting displacements of the ossicles (small bones in the middle ear). Incidentally, the vibration mode for 143.8 kHz, which is only slightly lower in frequency, is completely different, as readers can verify by clicking here.
At this point, I’d like to invite readers to stop, and ask themselves whether they still believe that an unguided process of stepwise random variations, culled by natural selection, could produce such an exquisite structure as the cetacean ear. The impression of design is overwhelming. I would like to stress that I’m not trying to make an argument here; for the time being, I’m simply making a rhetorical point, and nothing more.
The authors of the above-cited article on hearing in toothed whales and dolphins, begin with an overview of the history of scientific research on the subject:
Hearing in dolphins was one of the first subjects addressed by early cetacean research teams [2]–[5] because they suspected that dolphins, like bats, used echolocation [6]. In the following five decades, several review papers on hearing and ear anatomy in toothed whales (odontocetes) have been published [7]–[14].
In spite of this long history of research, the structure/function complex that is the odontocete hearing apparatus is still poorly understood. Over the past forty years there has been general agreement that sound enters the dolphin’s head through the “acoustic window”, a thinned portion of the posterior mandible (Figure 1), and is transmitted via the mandibular fat body (MFB) to the bony tympanoperiotic complex [8]. In the time since Norris’ seminal paper was published, several studies have produced evidence that sound also enters the MFB via a “gular pathway”, i.e., through the soft tissues around the tongue and throat, eventually passing through the opening created by the absence of the medial bony wall of the posterior mandible [8], [15]–[19]. Discussions continue as to whether the middle ear with its specialized ossicular triumvirate also functions in odontocete hearing [13], [20]. Different explanations for the transfer of sound energy to the inner ear have been offered (for a review, [21]).
The focus of this paper is functional in nature. Traditional anatomic methods and technologically sophisticated techniques allowed us to piece together this puzzling part of the odontocete sound reception apparatus. Sound is “received” over the surface of the animal’s head, entering channels (Figures 1, 2, 3, 4 and 5) that eventually lead to the bony ear complex (Figures 6, 7, 8, 9, 10, 11, 12, 13 and 14). The sound reception apparatus, or peripheral auditory system, is comprised of an intricate set of structures that includes fat pads and channels; thin and thicker wafers of dense bone, sheets of connective tissue; along with the requisite muscles, innervations, and vasculature. We assert that, by various means, this structural amalgamation filters and transmits selective acoustic frequencies to the tympanoperiotic complex (TPC), which contains the inner ear of the cochlea (Figure 12). This study of the sound reception system collected data using multiple methods, such as hand dissection, remote imaging followed by digital image-processing, and functional analysis using finite element modeling simulations. We also present a unique analysis of the vibratory complexity of the bony TPC (Figures 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36 and 37).
The authors conclude:
Our proposal is that acoustic signals enter over the surface of the head, are variously filtered or amplified by anatomic components, while propagating to and through the MFB [mandibular fat body – VJT], and eventually exert sound pressure across a mosaic of bony patches of varying thinness. The sound pressures are summed across the mosaic of bony elements and are transduced into mechanical displacements that result in complex vibrations of the entire TPC [tympanoperiotic complex – VJT], including the ossicular chain (Figures 25, 26, 27, 28, 29 30, 31, 32, 33 and 34). If this proposal for the transduction mechanism is correct, it follows that the patterns of sound pressure on the actuated bony surfaces of the TPC are so complex that the intricate vibrational interactions can only be seen with the aid of computers.
…The vibrational analysis represents a leap forward in experimentation with this complex system. It shows that the TPC, with bones of varying thicknesses, joints, and soft tissues, is capable of fundamental vibrational states that are more complex than previously reported.
It may amuse some readers to learn that the authors of the fascinating article I’ve been citing appear to be devout neo-Darwinists. For example, when discussing vibrating modes of the “ear-bone” at higher frequencies, the authors write:
One may conjecture that a mechanism like this may have evolved to compensate for the attenuation of high frequencies in biological tissues. (Italics mine – VJT.)
Conjecture, indeed!
What about whale evolution?
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Left: Indohyus major, an alleged whale ancestor from the Middle Eocene of Kashmir. Image courtesy of Nobu Tamura and Wikipedia.
Right: Pakicetus innachus, a whale ancestor from the Early Eocene of Pakistan, after Nummelai et al., (2006). Image courtesy of Nobu Tamura and Wikipedia.
A diagram showing the evolutionary history of cetaceans. Image courtesy of G1noah and Wikipedia.
Recently, I’ve been reading about the evolution of whales. As most readers will be aware, I happen to think there are powerful arguments for the view that all living creatures are descended from a common stock. For that reason, I don’t have a problem with the hypothesis that modern whales are descended from a creature that looked rather like Indohyus (pictured above left), although I will note in passing that the relationship of Indohyus to modern whales remains somehwat controversial. What I do have a problem with is the Darwinian view, that the process by which modern whales evolved from a creature resembling a mouse-deer was an unguided one, completely explicable in terms of chance (random variation) and necessity (natural selection) without the need for any Intelligent Designer.
I was intrigued to learn recently that Indohyus possessed an unusual bone structure around its ear. Professor Hans Thewissen at the Northeastern Ohio Universities College of Medicine, the leader of the team that reconstructed the skeleton of Indohyus in 2007, described his reaction upon seeing the bone, to science reporter Ian Sample, from The Guardian:
“When I saw it, I said ‘Oh my God!’ In most mammals the bone is a little bowl-shaped structure, but in whales the shape of the bone that makes up the ear is unique and in Indohyus it is the same. The inside of that bone is very thick, and on the outside, it’s very thin, the difference is giant. No other mammal has that,” said Thewissen.
However, when I investigated the evolutionary transformations of the ear bones in the lineage leading from the earliest whale-like creatures to modern whales (see the chart above), I was surprised to find that each of the alleged evolutionary intermediates appeared to have undergone not one but multiple modifications from its predecessor, in the design of its ear. A striking illustration of this can be found in Figure 7 on page 282 of Dr. Zhexi Luo’s article, “Cetacean Ectotympanic Structures” in The Emergence of Whales: Evolutionary Patterns in the Origin of Cetacea edited by J.G.M. Thewissen (Plenum Press, 1998) and also in Figures 27 and 28 on pages 77 and 78 of the (dauntingly technical) 1999 monograph by Zhexi Luo and P. D. Gingerich, entitled Transition from terrestrial ungulates to aquatic whales: transformation of the basicranium and evolution of hearing in Papers on Paleontology (Monograph) 31: 1-98, Museum of Paleontology, University of Michigan, Ann Arbor, Michigan. Even if you don’t understand mosty of the anatomical terminology in Dr. Zhexi Luo’s articles, two things stand out at once.
First, if you examine the evolution of hearing in whales, it is immediately apparent that each of the alleged evolutionary intermediates is strikingly different from its predecessor, in structure. This may simply be because there are many intermediate forms which scientists haven’t yet discovered. But my point is that given what we know, the evolutionary “stepping stones” are still very far apart from one another.
Second, hearing in whales is a very complex process, which requires the co-ordinated interaction of multiple parts. I am not saying that the ear of whales is irreducibly complex, in the sense defined by Professor Michael Behe. What I am saying is that the sheer complexity of the cetacean ear and the inter-dependence of its many parts renders the claim that an unguided process could transform the ear bones of (say) Indohyus or Pakicetus into those of a modern whale highly implausible. It is incumbent on those making such a claim to “show workings” – that is, put forward a plausible step-by-step pathway, showing how it could have happened.
Third, a lot of evolutionary innovations (or apomorphies) seem to have occurred over a very short period of evolutionary time, in the lineage leading to whales. For instance, Zhexi Luo, on page 274 of his article, “Cetacean Ectotympanic Structures” in The Emergence of Whales: Evolutionary Patterns in the Origin of Cetacea edited by J.G.M. Thewissen (Plenum Press, 1998), listed the following six apomorphies in the ear bones as hallmark traits of the “post-Pakicetidae” Cetacea – in other words, creatures in the whale line after Pakicetus, which means the Protocetidae, as well as their descendants, the Basilosauridae and the Dorudontidae, the latter of whom gave rise to modern whales, which fall into two groups – baleen whales (Mysticeti) and toothed whales (Odontoceti):
(a) An incipient conical apophysis.
(b) The tympanic opening for the external meatus is reduced.
(c) The sigmoid process is twisted and has involuted margins.
(d) Elongate posterior process of the ecotympanic to cover the entire length of the mastoid process of the petrosal. The posterior portion of the posterior process is a horizontal plate (not vertical).
(e) A median furrow on the ventral surface of the bulla.
(f) Double pedicles for the posterior process of the tympanic bone.
(Sorry for the anatomical jargon. If anyone can interpret it, they’re welcome.)
Maiacetus, a whale in the Protocetid family. Image courtesy of Cliff, FunkMonk, National Museum of Natural History and Wikipedia.
So there were six evolutionary innovations which appeared for the first time in the protocetids! That’s a whole lot of evolution going on, and all in the one organ: the cetacean ear.
To be clear, I’d like to point out that Dr. Zhexi Luo is no friend of Intelligent Design: he discusses the homologies between whales and their near relatives within a Darwinian framework, and he also invokes embryology to explain some of the distinctive traits of whales. That’s fine, but I have to say that I found no detailed explanation for the origin of any particular structure in the ear of whales.
Five Notions of Possibility
When people talk about what’s possible and what isn’t, they are generally using the word “possible” in one of four senses. First, there’s logical possibility. Philosophers love this one. A square circle is logically impossible: it’s a contradiction in terms. But once you get away from logical definitions, anything goes, as far as possibility is concerned. This kind of possibility is irrelevant to science.
A second kind of possibility is nomological possibility, which is defined by what the laws of Nature allow. For instance, transmitting information faster than the speed of light is nomologically impossible, as is a perpetual motion machine, which violates the first and/or the second law of thermodynamics.
Some physical outcomes are technically permitted by the laws of Nature (and hence nomologically possible), but are astronomically improbable in practice. For instance, it is thermodynamically “possible” that all the molecules of air in the room where you are sitting will rush over to one corner, leaving you in a (very temporary) vacuum. Since the number of molecules is very large, however, the probability of this happening is vanishingly low. If neo-Darwinian evolution were possible only in this sense, no-one would take it seriously as a scientific theory. Clearly, something more is needed.
A third kind of possibility relates to practical demonstrations. Clearly, if something can be shown to actually happen, then it must be possible. Many scientists – including, famously, Lord Kelvin in 1895 – used to deny the very possibility of manned heavier-than-air flight using powered machines with wings. However, the Wright brothers’ flight in 1903 demonstrated that it was possible. In a similar fashion, neo-Darwinists often argue that evolution has been demonstrated to occur. While this is true, it is utterly irrelevant to the kind of evolution we are considering here: the evolution of a new, complex structure containing multiple parts (fifteen, in the ear-bone of the Pacific white-sided dolphin, as we noted above). To claim that the distinction between this kind of evolution and the kind that scientists observe in the laboratory is a merely quantitative one is to beg the question. What’s more, it invites the obvious question: if the difference between “micro-evolution” and “macro-evolution” is one of degree, then how many orders of magnitude are we talking about? Quantify, quantify, quantify!
It might be argued, however, that given enough time, the evolution of a complex structure is a reasonable expectation. After all, we weren’t around when South America broke away from Africa around 110 million years ago, yet we are quite sure that it happened. But this is a fallacious argument. In the case of continental drift, we already know that the continents are moving at a certain rate (which is anywhere from 1 to 9 cm per year, depending on the plate). It is a simple matter to extrapolate from this fact, and show that over a period of 110 million years, continents can move thousands of kilometers apart. However, the problem with the evolution of a complex structure (such as the cetacean ear) is that scientists currently have no metric for a process they can observe, which would allow them to calculate how long it would take for the structure to arise. So we are back at square one again.
A fourth kind of possibility relates to mathematical probability calculations. Actuaries use this kind of possibility all the time in their work, and they use it to advise us on what risks we should insure ourselves against. Scientists (including engineers) use it too. But the problem for evolutionists is that scientists currently have no way of calculating the probability of a complex structure arising by Darwinian processes within a population, over a specified period of time.
That leaves us with a fifth kind of possibility: in everyday parlance, we say that something is possible if it’s do-able by some intelligent agent (usually ourselves). On May 25, 1961, President Kennedy pledged to put a man on the moon by the end of the decade. He clearly thought it was humanly possible – and he was right. Apollo XI touched down in the Sea of Tranquility on July 20, 1969. However, this kind of possibility is no help to the neo-Darwinian theory of evolution, which is, by definition, a theory intended to explain the origin of the various life-forms we find on Earth today (including whales), without having recourse to intelligent agency.
Argument from personal incredulity
Earlier on, I invited my readers to stop, and ask themselves whether they still believed, after viewing the five pictures that I discussed above, that an unguided process of stepwise random variations, culled by natural selection, could produce such an exquisite structure as the cetacean ear.
At this point, skeptical readers will want to retort: “That’s an argument from personal incredulity! It’s unscientific! Just because you can’t imagine how something can happen, it doesn’t follow that it’s impossible!” But I’m not trying to make an argument here. Instead, what I’m doing is shifting the argumentative goal-posts. All too often, Darwinists are inclined to claim victory, simply because they’ve refuted arguments designed to show that evolution by natural selection is impossible. What they fail to realize is that refuting an argument designed to show that evolution by natural selection is impossible is not the same as mathematically demonstrating that the evolution of a particular structure (such as the cetacean ear) is possible. And by “possible” here, I mean: “having a probability of occurring on Earth within a specified period of time, which exceeds the minimum threshold for an event to be deemed scientifically plausible.” Different writers have suggested different thresholds in the scientific literature; for my part, I’m quite happy to use the most generous estimate: Professor Dembski’s original value of 1 in 10^150 (that’s 1 followed by 150 zeroes).
If neo-Darwinists can show that the probability of a whale’s or a dolphin’s ear evolving from the ear of (say) Indohyus or Pakicetus, or some similar creature, over a period of 50 million years (I’m feeling very generous today) exceeds this threshold value, then they’ve established their case. But until then, if they’re true scientists, neo-Darwinists should have the honesty to admit that the possibility of their theory to account for large-scale evolutionary changes over the course of time remains undemonstrated, and that other theories which do not face this explanatory impediment might turn out to be true.
Curiously, though, the subject of origins is one on which true scientific detachment appears to be all but impossible. I have yet to meet a detached Darwinist who looks in the mirror every morning and says to him/herself: “I might be completely wrong.” I can, however, think of people in the ID camp, who are ready to acknowledge that they might be mistaken. Let my readers judge. On which side does honesty lie?
Epistemic short-cuts taken by neo-Darwinists
At this point, knowing that they’re boxed into a corner, many neo-Darwinists fight back by ridiculing the concept of Intelligent Design. “Why would a Designer make things through a guided evolutionary process?” they ask. “Why would He make parts of the cetacean ear by modifying pre-existing parts of other animals’ ears? Why not make them from scratch, instead? And why would He take 10 to 15 million years, instead of doing the job overnight?” The way they figure it, if they can make Intelligent Design look ridiculous, then Darwinism – or some hypothesis like it – must be true.
But this is a psychological argument. It presumes that the Designer of life is interested in making things in the shortest possible time, regardless of the effort involved. But if the Designer operates according to an “economy of effort” principle, then He might prefer to make whales by modifying the body parts of pre-existing creatures, and He might introduce evolutionary innovations at spaced intervals rather than all in one hit, because He is regulating the evolution of not just one kind of animal, but of entire ecosystems. Until we know the Designer’s utility function, we simply cannot take psychological arguments as decisive refutations.
I conclude that it is time for neo-Darwinists to show some intellectual modesty. The intricacy of the cetacean ear should fill us all with awe. While there might turn out to be a matter-of-fact explanation for its development, which does not invoke Intelligent Design, I’ll believe it when I see it – with quantitative calculations attached. Until then, color me a Darwin skeptic.
And now, some light music
I thought I might conclude this post on a light note, with the lyrics of the song, “Whale of a Tale”. Readers can listen to it online here. Enjoy!
Whale of a Tale
Got a whale of a tale to tell ya, lads
A whale of a tale or two
‘Bout the flapping fish and girls I’ve loved
On nights like this with the moon above
A whale of a tale and it’s all true,
I swear by my tatoo
There was Mermaid Minnie
Met her down in Madagascar
She would kiss me
Anytime that I would ask her
Then one evening
Her flame of love blew out
Blow me down and pick me up,
She swapped me for a trout!
Got a whale of a tale to tell ya, lads
A whale of a tale or two
‘Bout the flapping fish and girls I’ve loved
On nights like this with the moon above
A whale of a tale and it’s all true,
I swear by my tatoo
There was Typhoon Tessie
Met her on the coast of Java
When we kissed I
Bubbled up like molten lava
Then she gave me
The scare of my young life
Blow me down, and pick me up
She was the captain’s wife!
Got a whale of a tale to tell ya, lads
A whale of a tale or two
‘Bout the flapping fish and girls I’ve loved
On nights like this with the moon above
A whale of a tale and it’s all true,
I swear by my tatoo
Then there was Harpoon Hannah
Had a look that spelled out danger
My heart quivered when she whispered,
“I’m there, stranger”
Bought her trinkets
That sailors can’t afford
(Sailors can’t afford)
And when I spent my last red cent
She tossed me overboard!
Got a whale of a tale to tell ya, lads
A whale of a tale or two
‘Bout the flapping fish and girls I’ve loved
On nights like this with the moon above
A whale of a tale and it’s all true,
I swear by my tatoo!