Tag Archives: Engineering

Deconstructing Dawkins 3 – A Case Study in Design

Schematic of the human eyeLast week, I wrote about some general problems I saw with Richard Dawkins’ claims of “sub-optimal design” in natural objects like the human eye. I recommended that we keep in mind our own finite knowledge and approach the matter with the same humility an engineer should approach a peer review of a colleague’s work. This week, we’ll need to get a little more technical to see Dawkins’ error, but let’s do a little “peer review” of that particular case of the human eye.

Dawkins’ problem with the eye is that the rods and cones (the photosensors) point toward the back of the eye, while the nerves (the “wiring”) come out the back of these sensors into the interior of the eye before being bundled up into an optic nerve that connects to the brain through a hole in the retina, causing a “blind spot” where there can’t be any sensors because of the hole and the nerve bundle. Admittedly, this is counter-intuitive. And yet, the eye is an amazing machine that the best human minds have not been able to rival. Whether it seems backwards to us or not, the eye seems to do better than we can with our “forward” thinking. Why might this backwards wiring actually be optimal?

Many times in my field, our structural systems are more complex than they could be otherwise because of other systems such as heating and air. Let’s face it, on a hot, humid, summer day in the Southern US, the best structure is useless if nobody can stand to be in the building because there’s no air conditioning. With the eye we have a similar issue: we need wiring (i.e. nerves) for data transmission, but we also need plumbing (i.e. blood flow) to supply energy – and lots of it. The rods and cones of the retina are so sensitive, that a single photon of light can be detected. This is because a series of enzymes massively amplifies this minuscule stimulus to useful proportions. But this enzyme activity also makes the photoreceptor layer of the retina have one of the highest metabolic rates of any known tissue[1] and the highest in the human body.[2] The energy for this is supplied by a bed of oversized capilleries immediately behind the photoreceptor layer that floods the layer with near-arterial levels of oxygenated and nutrient-rich blood to satisfy these high metabolic demands. This arrangement of blood supply allows a high packing density of the rods and cones making up the layer, which allows for increased visual resolution. In the opinion of biochemist Michael Denton, it is “hard to imagine how a standard-type capillary network to carry the necessary quantities of blood directly through the photoreceptor cell layer could be arranged without causing at least some decrease in the packing density of the photoreceptors and a consequent decrease in the resolving power of the eye.”[1] Considering also that blood strongly absorbs light, this plumbing system can’t be in front of the photoreceptors, even though that would allow for the nerves to be routed to the rear and more “tidily” as Dawkins suggests. In fact, any other arrangement in humans appears  to create bigger problems than it solves.

However, atheists have looked to the cephalopods like the octopus and squid as examples of creatures with good eyesight whose eyes are wired “correctly” – photosensors facing forward, toward the light, and nerves directed toward the brain – eliminating the admittedly minimal blind spot of the human eye. Although their visual acuity is comparable to some fish that have inverted retinas like us, octopuses operate in environments where ambient light is more diffuse or even negligible for the deep-sea dwelling varieties. Whereas we would actually need something to reduce the amount of incoming light if our sensitive photoreceptors faced the light like theirs, that placement is an advantage in their environments. Energy conservation can also be a design parameter. In fact, studies in different species of flies have shown that optical data transmission from photoreceptors increases with light, and there is an energy cost associated with photoreceptor activity which is at a minimum in total darkness and a maximum in full daylight. This cost can be significant as one species of fly tested used up to 2% of its total base metabolic rate just powering the photoreceptor layer of its eyes. And that was just the “ready state”, in total darkness. As ambient light increases, optical data increases, and with it, energy demands. However, the octopus’s copper-based blood, hemocyanin, only supplies roughly one-quarter of the oxygen as our iron-based hemoglobin.[4] Based on the experimental confirmations from the fly testing, it is reasonable that humans operating in full daylight will have a much higher metabolic demand than the octopus operating in the subdued light of shallow water or the near darkness of deep water. This then makes perfect sense for us to have the inverted retina we have, with its high-capacity power delivery system, while the verted eye of the octopus is more reasonable in their environment. Our inverted photoreceptors then appear to be the best possible solution, even with the introduction of a blind spot. However, this blind spot is situated in an area of each eye not used for focused vision, is in a different spot in each eye so that the input from the other eye compensates for it, is adequately corrected for in the image processing  occurring in the brain, and is actually a smaller blind spot (approx. 6°) than the most obvious blind spot for humans: our own nose, which blocks out a larger field of view for each eye.

One last thing to point out to armchair engineers like Dawkins is this: show me we can do better. If our eyes are so offensive, show how we could improve on them. Yet with all our scientific knowledge and advancements in technology and some of the best human minds working on a visual prosthetic for blind people, the pursuit of a man-made eye is still woefully primitive. It seems extraordinarily hypocritical to me to criticize another’s design, whether a fellow engineer’s or God’s, if I can’t even come close to designing something comparable. We are at the level of allowing a blind person to differentiate between light and dark, between the presence of a large opening like a door versus a solid wall, and between crude outlines of shapes that would make the old PONG computer game of the 80’s seem like an IMAX 3D movie. It’s easy to criticize something from afar. But in engineering, getting intimately familiar with the details of a problem is what makes or breaks a design. And the more we familiarize ourselves with the constraints and objectives of the human eye, the less we find to criticize.


[1] Michael Denton, “The Inverted Retina: Maladaptation or Pre-adaptation?”, 1999. Hat tip to blogger Wintery Knight for publicizing Denton’s research.
[2] Punzo, Xiong, and Cepko, “Loss of Daylight Vision in Retinal Degeneration: Are Oxidative Stress and Metabolic Dysregulation to Blame?”, Journal of Biological Chemistry, January 13, 2012.
[4] https://en.wikipedia.org/wiki/Hemocyanin, accessed 12/8/2015.

Deconstructing Dawkins 3 – Optimal Design Overview

Richard DawkinsRichard Dawkins has made much of the “appearance of design” in biology being a false positive, and the notion that living creatures actually exhibit bad design that negates the idea of an omniscient Creator. After all, why would God, if He existed, and if He was all-knowing, do things like wire the human eye “backwards”? This is, according to Dawkins, a sub-optimal design that any engineer would reject out of hand, or get fired if he submitted a design like this to his company. In fact, regarding the “backwards wiring” of the vertebrate eye, he admits that it doesn’t actually have much effect on vision, but “it is the principle of the thing that would offend any tidy-minded engineer!”[1]

Oh really? Since he decided to drag us engineers into this, I’d like to ask one question: what exactly do you mean when you talk about an optimal design? I can tell you most engineering designs end up being sub-optimal, regardless of how “tidy-minded” we may be. That’s because we routinely have to make trade-offs between competing goals. I have a book on wood-framed shearwalls that humorously highlights this issue with a side-by-side photo of an “engineer’s dream wall” and an “architect’s dream wall”. The engineer’s wall is very stout and very solid. The architect’s  preference (and most owner’s) is one completely filled with beautiful expansive windows. Which one is the “optimal” wall? Neither one of us is getting what we would call the optimum. Us engineers need some minimum amount of strength that the windows aren’t providing, and the architect needs some minimum amount of holes in our solid wall so the owner doesn’t feel like he’s living in a dungeon! Factor in things like cost and meeting building code constraints and “optimal” becomes a very subjective term with different meaning to different stakeholders. But this is the way most design goes. You can’t maximize one parameter without minimizing another, and at some point, you’ll have 2 (or more) parameters that conflict. Do you focus entirely on the first, or the 2nd? Do you balance them equally? Maybe a weighted average based on your best guess as to which one will govern more often? Unfortunately, no matter which route you choose, someone will come along later, with the benefit of hindsight, and ask why you didn’t do it some other way. But God, being omniscient, has perfect foresight, so that shouldn’t be an issue for Him, right? True, He won’t make a mistake in design due to lack of knowledge or not anticipating future conditions, but the aspect of competing design parameters still applies.

Versatility and specialization are two such competing parameters. Specialized designs seek to maximize a positive parameter like speed or strength, or to minimize some negative parameter like weight or waste, at the expense of other factors. This is evident in animals like peregrine falcons whose hollow bones minimize weight, while their aerodynamics maximize speed. Versatile designs, on the other hand, seek to balance the most parameters at one time to achieve adequate performance over a wide range of conditions. This allows the object to fulfill many roles, or to survive in a variety of unpredictable conditions and possibly even excel over more specialized objects if conditions are constantly changing. Humans, for example, are extremely versatile. We may not thrive as well on our own as more specialized animals in arctic or desert or tropical environments, but unlike most of them, the same human can generally still survive in all of them. And, besides this highly versatile body design, we have the brains to make tools, and shelters, and transportation to overcome our bodily limitations, such that we can even survive in places like outer space where no animals, however optimized, can survive.

So is God required to maximize all parameters that go into a design? No. Some may fall into the category of “square circles” where the parameters are simply mutually exclusive. Is He required to maximize the particular parameter we favor over another that He deems more important? No. As professional engineers, we can seek the input of peers if desired, but nothing says we have to take their advice. The engineer signing off on the design and taking full responsibility decides the direction of the design. Is so-called “bad design” evidence against God? No. It simply means we likely aren’t seeing the whole picture. My own peer reviews of other engineers’ designs have raised questions as to why they chose a particular route, but then they proved quite reasonable after getting those questions answered. It was typically my lack of knowledge of the background of that particular project, or my unfamiliarity with some certain condition they’d been burned by before that made me think they’d missed something “obvious” when they had actually thought through their design better than I might have if I’d been in their position.

Engineers must approach peer reviews with an attitude of humility, but even more so if the design being reviewed is God’s. If I can overlook the good reason a fellow human engineer made the design choices he did, then I should be all the more open to the possibility that I’ve missed something an omniscient Designer did consider. And this is where I would encourage people like Dawkins not to arrogantly assume that there is no good reason for something just because they can’t see it. Tune in next week as we focus on a couple of specific examples where the atheist claims of “sub-optimal” and “bad” designs in nature have actually turned out to be engineering masterpieces.

[1] Richard Dawkins, The Blind Watchmaker (London: Penguin Books), p94.

Skeptical of Skepticism

Scale smallAs an engineer, I realize that we can sometimes be a pretty skeptical – even cynical – lot. We are to put the safety of the public first, and so our job often requires us to be critical of whatever we’re reviewing, looking for anything deficient that might endanger future occupants or users of our designs. We are always under pressure to develop more efficient, optimized solutions to save time, money, labor, space, etc. And so we have to be critical of even our successful designs. Sometimes we are called to peer review another engineer to critique their design. Forensic investigations may require us to specifically look for what went wrong with another engineer’s design. As Scott Adams has pointed out in his funny, but often cynical, “Dilbert” comic strip, every engineer wants to retire without any major catastrophes being tied to his name. So skepticism often comes with the territory in engineering, and often serves us well as we seek out the best course of action among many mediocre choices, and more than a few really dangerous choices.

Because of that, I understand why a lot of my colleagues are skeptical of Christianity, and I don’t fault them for it (to an extent). A certain amount of skepticism is healthy. In fact, Jesus told His disciples to be “as cunning as serpents and as innocent as doves” (Matt 10:16). A healthy skepticism makes us look carefully at what’s before us and not get taken in by every half-baked idea that comes along. The word skeptic actually comes from the Latin “scepticus” meaning “thoughtful, inquiring” and the earlier Greek “skeptikos” meaning “to consider or examine”. Thoughtful examination is certainly not a bad thing. But one thing I’ve noticed is a tendency to a one-sided skepticism (e.g. skepticism of Christianity without any corresponding skepticism of atheism). That is where I think we do ourselves a disservice. Our design codes often describe particular accepted methods, and then allow a catch-all case like “… or alternative generally accepted methods based on rational engineering analysis”. We engineers take pride in our openness to alternatives as long as they can be backed up with proof. Yet if we don’t give one side of a debate a chance to prove itself, and give the other side a free pass, are we really exercising  “thoughtful examination” of the issue? I don’t think so. We need to thoughtfully consider both sides of the debate to draw our conclusion.

One thing I’ve found in looking at atheistic arguments is that they often employ circular reasoning by assuming that the supernatural is impossible as they argue that there is nothing supernatural. I can’t assume what I’m trying to prove, and neither can they. It’s a logical fallacy for both of us. I’ve seen several cases of atheist forums referencing Biblical “absurdities” where the Bible doesn’t even say what they considered absurd. And yet many won’t look up the reference for themselves to verify the truthfulness of the atheist claim. Folks, that just won’t fly. I don’t ask for a free pass for Christianity, but I’m not giving one out to atheists, agnostics, or anyone else either. If you have a case, then know it, make it, support it, defend it. It takes more work to do your own research instead of just forwarding a link from a blog or web page supporting your view, but it’s worth it. In engineering, we often hand-verify the output from new unfamiliar software. It’s tedious and time-consuming, but once we understand how the program arrived at it’s answer, once we have confirmed the truthfulness of the output, we can use it with confidence; and if something changes, we’re more likely to recognize false output. Similarly, studying my own side and the opposing view with fairness takes time, but I want the truth, and I know it’s worth it. Consider this, whether Christian or not: if Christianity is true, and there is something beyond this physical life and our status in that later stage is determined by choices we make here and now, wouldn’t it be of the utmost importance to determine if that were true? I could die in a car crash tomorrow, so I’d better not put off that decision. If atheism is true, then that’s the end of me. It seems a little unfair that I didn’t live very long, but that’s the way it is (possibly). If Christianity is true though, then that’s a total game-changer, and I better know the answer to that question for myself and not just rely on others to determine my fate.

Of Moment Frames and Church Hymns

Concrete moment frames destroyed in 1994 Northridge quake
Concrete moment frames after 1994 Northridge quake

One song that we sometimes sing at my church has a verse from an old hymn mixed into it:  “I dare not trust the sweetest frame, but wholly lean on Jesus’ name”.

In my profession, we use different types of frames to resist earthquakes and wind forces.  In our area, two types dominate: moment frames and concentrically braced frames. Over the years, I’ve gotten to attend seminars and read trade journal articles about other types of frames like eccentrically braced frames, buckling-restrained braced frames, and special truss moment frames that attempt to withstand wind and earthquake forces in their own way, and with varying levels of efficiency. But always, I am reminded that even with the best plans, the latest tools, the newest techniques, the most up-to-date research, the most complex analyses, and the most complete calculations, they are all still fallible and not completely trustworthy, just like the “sweetest frames” that were rendered into rubble during the Northridge earthquake of 1994.

Despite our best attempts to make trustworthy frames of our own to withstand life’s unexpected disasters, there is only one sure foundation, only one support who can take our heavy burdens without yielding, only One who is worthy of all our trust, no matter what. That the fallible designs of our minds and the imperfect works of our clumsy hands are not the best there is; that we don’t have to resign ourselves to only being able to trust in things or people that have disappointed us before and likely will again; that rather we can “wholly lean on Jesus’ name” as the one stable and unmovable framework in our lives; that’s something to be grateful for!