The Gas Exchange Problem Insurmountable by Chance
In Part Two of Dr Smith’s guest article,
he applies irreducible complexity to
how complex animals get oxygen to cells.
Explaining Life’s Wonders, Part II:
Irreducible Complexity’s Gas Exchange Mystery
by James O. Smith, M.D.
In part one, we surveyed some of the major mysteries that have to be confronted when we ask about the origin story of life’s wonders. Then we looked at structures that commonly exhibit what can be called irreducible complexity. We noted that biologist Michael Behe showed in Darwin’s Black Box that many bacteria have an outboard engine called the flagellum which depends on over three dozen protein parts, all of which are necessary for building and operating the system. We pointed out the core of this microbial wonder: a biological motor that powers the flagellum. Its three main structures are made independently, using different sections of the bacterial genome, and the absence of one of the three would be a fatal flaw.
With a tip of a very respectful hat toward Dr. Behe, one might fairly theorize that the three main structures of the flagellar motor are just the current functional parts of this essential engine, but that perhaps some simpler, weaker system predated what is now observed. Maybe two of the three parts were working in a clumsy way, but were superseded by a superior design, causing the genetic traces of the less-functional predecessor to fade out of the DNA of the surviving, newly superior animal. There is no way of determining if this is so; it is a grand supposition that the imagined former (simpler) structure would have been sufficient to sustain effective propeller motion to promote survival at all.
The Gas Exchange Mystery
Now the problem explodes in difficulty when we shift to mammals and mankind. Other life-and-death cases of irreducible complexity (IC) exist in our arena of life that are far more critical than the flagellum. For example, systems of gas exchange in mammals provide a plethora of biochemical structures, all of which must either function in unison or result in death, often in minutes. Here we have no “proving ground” of extended generations of individuals that are subject to the competition of natural selection. In other words, these irreducible complexities (ICs) do not bear the luxury of an expanded denominator that allows massive durations of time to allow variation, coordination, and survivable function.
This discussion is not an argument in the “God-of-the-gaps” department. There are amazing structures that seem beautiful, or extraordinarily interactive with other species, and produce a sense of awe in those who would attribute these features to a Creator. But their functionality and their essential nature and interaction provide a convincing example of irreducible complexity. For a naturalistic explanation of complexity to remain credible, it must account for the presence of these systems.
I am writing from the standpoint of a physician (cardiologist) and not a biochemist. I will yield to any professional biochemist whose work in this area is clearly deeper and more detailed than my own. Yet medicine has this advantage: it involves understanding of the functional capacity of biological chemicals and structures, and when pondering the essential nature of systems such as gas exchange, it is one thing to know why a patient died, and another to find out why he is dying and to alter the process and save the life. Again, the denominator or time is different in both discussions.
When a person breathes in, a composite of nitrogen, oxygen, and carbon dioxide and other gases is moved physically into the chest. In addition to muscular and air passage structures (and functions), we come to the other end of our vital system. I’m referring to the remarkable system in mammals that brings the oxygen in this quantity of air into close contact with the blood stream, which is branched into microscopic pulmonary capillaries. There is a critical distance that the oxygen must traverse in order to be taken from the air into the bloodstream. There are chemical affinities that cause this motion to occur. If the chemicals are not exactly correct, or if a poison such as carbon monoxide (with a greater affinity for the bloodstream chemicals) is present, or if the distance is too great for the oxygen to travel, oxygen delivery fails. The individual, without intervention, may survive a few minutes. No time for evolution to occur. So this is one of many ICs in the mammalian system.
A second IC is observed in the transfer of carbon dioxide out of the tiny air sacs lungs. If carbon dioxide could not be released, oxygenation cannot occur.
A third IC is observed in the relatively complex biochemical, hemoglobin. This protein is comprised of four globulins which form a stereochemical (solid) structure even though still dissolved in the blood. In the center of the convoluted amino acids that form the globulins, a planar ring is positioned. It contains iron molecules that produce the chemical attraction of oxygen into the ring. After being oxygenated, the blood enters the heart and is pumped to the extremities. At the cellular level, a different affinity exists that pulls the oxygen off the hemoglobin, from which it is used in metabolism. Obviously, the pumping heart is an IC, as is the cellular system that takes the oxygen. The blood vessels themselves are an IC.
Transferring oxygen from the air to the cell is the product of a series of ICs. But this comparatively simple process would be further complicated by one essential of life, namely childbirth. Obviously, producing subsequent generations is essential to the survival of a species. But a problem arises in delivering oxygen to a fetus in the womb. It does not have the capacity to breathe in outside air. It can only leach oxygen from its mother, but if its hemoglobin is the same as hers, there would be no biochemical drive to move the molecule from her to her baby. Another IC exists right here, without which reproduction would be impossible. Fetal hemoglobin (HgbF) is different than normal adult hemoglobin (HgA), and has a greater affinity for oxygen, as well as the capacity to diffuse off carbon dioxide.
So, the successful individual must have a unique pattern of DNA codons for HgbF as well as HgA in order to survive in the womb. The next IC is observed in the cessation of producing HgbF, although it has superior oxygen affinity. If it retains its superiority, the very next generation has no means of assimilating oxygen from the environment.
To summarize…
If no muscular function to
move air into the chest: dead
If no alveoli: dead
If alveoli too big: dead
If alveolar wall too thick: dead
If imperfect hemoglobin: dead
If imperfect ferritin ring: dead
If no second hemoglobin: dead
If inadequate heart function: dead
If no vascular structure
between heart and cells: dead
If no cellular affinity: dead
If no metabolic system: dead
If inability to release CO2: dead
In all these subsystems, gas exchange must be present, functional, and integrated with all the other systems in order to sustain life. It might be fair to presume that systems such as the vasculature may have arisen through some process that took a great deal of time (a large denominator). For the majority of the above, however, function must be immediately available, or death ensues.
To consider just one further extension of the ICs above, cardiac function is worthy of observation. The complexities are far too extensive to catalogue, and amazing structures and function are still being discovered. Essentially, all of these contribute to sustaining the overall function of mechanically pumping oxygen-rich blood to structures that are unswervingly dependent on it.
Consider as well that this heart forms from a microscopic tube and swells into a structure that moves almost as soon as it is formed. Intrinsic in its design is a series of membrane pumps that depend on electrolytes (sodium, potassium, calcium, etc.) flowing rapidly in and out of the cardiac cell, causing it to beat, and to reset in milliseconds, ready to beat again. If these pumps do not function perfectly, death follows. These cells start themselves, adjust to the needs of the body, increase and decrease their rates, reset within milliseconds, and sustain life for up to a century or more.
The blood it pumps contains myriad proteins, white blood cells, platelets, and the serum allows life-sustaining nutrient to be transported through the body to each individual cell. It has a viscosity that allows ideal flow, and an inherent capacity to clot when exposed to air (or other substances).
The lungs that contain the air sacs are powered by a system of muscle that move air in and out. The multiple levels of branching make for tiny air sacs, small enough to allow oxygen and other gases to move across the alveolar membrane and into the bloodstream. The process of breathing continues automatically, another IC without which every organism would die when it fell asleep or simply forgot to breathe.
In summary, there are serious obstacles to the presumption that simple life can change through the engines of mutation and natural selection. One of these obstacles is the concept of irreducible complexity. In gas exchange, any hypothesis of the gradual rise of our tight balance of multiple ICs is shown to be extremely unlikely. It seems acutely unreasonable to reject a hypothesis of genuine design by intelligent agency. We feel the aching unlikelihood of “chance mutations” as the author of this system. This is magnified by the extremely short duration of time available to allow for changes, no matter how small.
Discovery Institute, 2022
Recommended Reading: Your Designed Body by Laufmann and Glicksman contains many more fascinating examples of IC systems that keep us alive. As the authors say, there are a thousand ways to be dead, but only one way to be alive.