This section is an example of intelligent design with systems within systems within systems that must all work together simultaneously to perform a function. You will see how complex these systems of life can be.
The process of breathing is another example of how interrelated systems cannot be made, developed or evolve one part at a time when each part must be individually useful. My training as an anesthesiologist gave me a thorough understanding of the way we breathe. It is not as easy as it looks! The purpose of breathing is to take in oxygen and to release carbon dioxide. The process can be described as the integration of several separate processes. There are the inspiratory mechanisms, expiratory mechanisms, the mechanisms of respiratory gas exchange, oxygen delivery mechanisms and the sensors to control and initiate these processes. The logic is that each of these systems requires the working presence of the other systems to have purpose. The requirement of evolution is that each step in the development of a system has to have purpose or it would never occur as there would be no survival advantage. The contradiction to evolution here is that there is no purpose to breathing in if there is no method to breathe out. There is no purpose of moving air at all if oxygen cannot be extracted. There is no purpose to oxygen delivery systems unless there is oxygen present to deliver. There is no purpose for control systems unless there are systems to control. If there is no purpose for an individual system then it could not have evolved because evolution requires each step to be both new and useful. The logic of this discussion is the same as with all intelligent design examples.
The numbers of examples of biologic systems to discuss in terms of intelligent design are limitless because of the huge variety of life and all are extremely complex. The following discussion of breathing is only one example from all of biology. It will require the use of many terms from anatomy, physiology and biochemistry that may be unfamiliar. There are so many parts in so many systems that it can be overwhelming to understand completely. Don’t worry if it doesn’t make total sense to you, it is the interrelatedness and complexity that is the important issue and that will be very clear. Many individual systems will be explained in detail and then put in the context of how each system operates for the purpose of breathing.
Breathing requires several systems to work together. There are inspiratory mechanisms to breathe in, expiratory mechanisms to breathe out, mechanisms of respiratory gas exchange to transfer oxygen and carbon dioxide from the lung to the blood, a method to transport oxygen and carbon dioxide in the blood, and the sensors to control, initiate, and coordinate these processes. Breathing is an example of systems within systems within systems. Now let’s examine each of these systems to realize how complex they are. Be aware that no single portion of the following discussion has any individual purpose without the working presence of every other complex system.
The first system to discuss is one of the many control systems. The act of breathing is called respiration and the regulation of respiration occurs in the parts of the brain called the medulla oblongata and pons. Our metabolism uses oxygen and creates carbon dioxide. So, the ultimate goal of respiration is to maintain ideal concentrations of oxygen and carbon dioxide in body fluids. There is a stimulus to breathe when either the oxygen is low so there will be more delivered to the cells, or when carbon dioxide is too high to remove it from the body. The respiratory center has an inspiratory area, an expiratory area and a penumotactic area. Each of these areas are groups of nerves. Behind the inspiratory center is a chemosensitive area which can sense the concentration of hydrogen ions in the blood. As carbon dioxide builds up in the blood it crosses the protective blood brain barrier and then undergoes a chemical reaction with water mediated by the the enzyme carbonic anhydrase to make bicarbonate and hydrogen ions. These hydrogen ions then initiate the sequence of events that signal the chemosensitive area to trigger the inspiratory area to send the signals to take another breath. So, the production of carbon dioxide by the cells is released into the blood, chemically converted to hydrogen ions in the cerebrospinal fluid, sensed by the chemosensitive area which stimulates the inspiratory center to take a breath that will eliminate carbon dioxide through the lungs. Of course each of these steps has no purpose without all the others and even with all of these working it only provides the information to the brain that a breath is needed. This has nothing to do with how a breath is taken or how the oxygen or carbon dioxide is transported.
This explains the central sensors in the central nervous system within the brain. There are also sensors for carbon dioxide and hydrogen ions in the peripheral chemoreceptor system. These are called the carotid bodies and aortic bodies because they are located in the carotid arteries and the aorta. Each of these chemoreceptor bodies has a special blood supply through dedicated individual small arteries. They send signals to the brain to tell of the need to breathe though the glossopharyngeal and vagus nerves. This is an independent system of sensors and is also integrated into the inspiratory center to initiate a breath in response to carbon dioxide increases.
The stimulation of respiration is nearly entirely from carbon dioxide, but there are also methods to stimulate a breath when the oxygen concentration in the blood is low. These sensors are only in the peripheral chemoreceptor system. The carotid and aortic bodies have the highest blood flow for any tissue in the body. They can sense the difference in oxygen concentration between the arterial and venous systems. The way these sensors work to send signals to the brain to tell of the need to breathe is so complicated that it is still unknown. The body is able to sense the need to breathe in two ways, buildup of carbon dioxide or low oxygen. There are both central and peripheral chemoreceptors. These chemoreceptors communicate with the inspiratory area in the brain.
The other two areas of the respiratory center are the expiratory area and the pneumotaxic area. The expiratory area is a group of nerves which when stimulated excites the expiratory muscles. This area is rarely active because expiration is normally from passive recoil of elastic structures of the lung and surrounding chest cage. This complex expiratory system is essentially a backup system that has little daily use. There is interaction between the inspiratory center and the expiratory center, but the mechanism of this interaction is not known. The pneumotaxic area transmits impulses continuously to the inspiratory area. The function is to limit inspiration and to turn off inspiration before the lungs become too full. There is a backup system for this as well. There are stretch receptors in the lung that transmit nerve impulses through the vagus nerve to the inspiratory center. These signals affect the inspiratory center in the same way as the pneumotaxic center to limit further inspiration when the lungs are full. The other system that coordinates the rhythm of respiration is the apneustic center in the pons of the brain.
The result of all of these systems creates a rhythm of respiration that is maintained without any conscious effort or awareness. They are a response to fine changes in concentrations of oxygen and carbon dioxide in our blood. The oxygen is used by our cells to maintain life by metabolism and the carbon dioxide that is produced must be eliminated. So there are chemical sensors in the body that can detect concentrations of both oxygen and carbon dioxide. These sensors are set at specific levels that support life. They are located in both the central nervous system and peripherally in the vascular system. These chemical sensors respond indirectly to carbon dioxide and actually respond to hydrogen ion which is produced from carbon dioxide and water with the enzyme carbonic anhydrase. These chemical sensors then send signals to the respiratory center which has three parts; the inspiratory area, expiratory area and the pneumotaxic area. The inspiratory center will initiate a breathe based on the signals it receives through nerves from the chemosensors. The inspiratory center is modulated by the pneumotaxic center in the medulla oblongata, the apneustic center in the pons and stretch receptors in the lungs to limit inspiration. The expiratory center is usually inactive because normal expiration requires no effort, but exists as a complex set of integrated nerves that can send signals to all of the expiratory muscles simultaneously for forceful expiration.
Let’s put this discussion in perspective. We know that for us to breathe several systems need to work together. There are the inspiratory mechanisms, expiratory mechanisms, mechanisms of respiratory gas exchange, oxygen delivery mechanisms and the sensors to control and initiate these processes. This initial discussion only considered the sensors and control mechanisms. This is an example of systems within systems within systems. The systems that sense carbon dioxide and oxygen concentrations and control the rate and depth of breathing are themselves made up of many other systems, each individually complex. Within the framework of intelligent design we can explain that there is no purpose for oxygen and carbon dioxide sensors if the nervous system is not already developed and able to transmit these signals to the inspiratory center. The inspiratory center has no purpose by itself as it needs coordination with the pneumotaxic area, apneustic area and stretch receptors to control both breathing in and breathing out. The inspiratory area, expiratory area, pneumotaxic area, apneustic center, stretch receptors, carotid bodies, aortic bodies, neurologic connections and biochemical pathways can all be thought of as individual systems that work together to perform the function of sensing the need to take a breath and controlling the rate and depth of respiration. Each of these systems is individually useless, and by the requirements of evolution could not have evolved independently as there is no independent purpose for any one of the systems. All of these systems have to be working together to sense the need to take a breath. This is in the larger context that sensing the need to breathe is only one part of the process of respiration, as there is no purpose for sensing the need for breathing if there is not already present systems that breathe in, systems that breath out, systems to exchange carbon dioxide and oxygen across the linings of the lung and systems to transport oxygen to the cells and to remove carbon dioxide from the cells.
Now let’s consider pulmonary ventilation, which means the inflow and outflow of air between the atmosphere and the lung. The lung can be expanded and contracted in two ways. Normal quiet breathing is accomplished nearly entirely by movement of the diaphragm. The diaphragm is a muscle between the chest cavity and the abdominal cavity. It has a very special dome shape when relaxed and flattens out to pull the lower surface of the lung down when contracted. When we breathe in the diaphragm is contracted, the lung is brought down to increase the volume which lowers the pressure in the air passages and air from the atmosphere is drawn in. Breathing out during quiet respiration uses no energy or effort. There is elastic recoil of the tissues in the lungs, chest wall and abdominal organs which compresses the lungs, increases the air pressure in the lung and air is forced out. For this system to work the diaphragm must be precisely positioned to completely separate the chest and abdominal cavity. Infants born with a diaphragmatic hernia (a hole in this muscle) die without medical care. The presence of this muscle, the specific shape, and position are essential to breathe. If it was shaped differently, placed slightly differently, or did not have the neurologic signals to coordinate the contraction breathing would not be possible.
The second way the lung can be expanded or contracted is by elevation or depression of the ribs to expand or contract the chest cavity. There is a specific structure to the rib cage for this to be possible. The ribs all slant downward from their attachment to the thoracic vertebrae. There are twelve ribs on each side that are connected to the vertebral column at a joint which allows motion. One muscle alone cannot raise the chest for a breath. There is a group of muscles of inspiration that work together to raise the chest. This group of muscles includes the sternocleidomastoid muscles, the anterior serrati, the scalenes, and the external intercostals. The sternocleidomastoid muscles connect the skull to the clavicles and contraction lifts the clavicles and breast bone called the sternum. The scalenes lift the first two ribs, the anterior serrate help lift the remaining ribs and the external intercostalis muscles are in a specific direction that allows for leverage between the ribs. All these muscles work together to expand the chest during heavy breathing. They are all connected to different bones of the skeleton and to specific parts of these bones so that contraction of these muscles at the same time creates the change in shape of the chest cavity to lower the pressure inside and force atmospheric air in. These muscles certainly would provide a survival advantage in the evolutionary scenario. The problem of course is that no one muscle can perform any useful independent function. They must all contract together to breathe heavily as is needed for running or exercise. The size, location, directional orientation, quantity, timing, and force of contraction are all perfectly and precisely integrated, coordinated and created.
There is a separate set of expiratory muscles that are needed during exercise when the elastic forces that work during quiet breathing are not powerful enough to cause the rapid expiration that is needed. These muscles pull the ribs down, compress the abdominal contents, and contract the chest cavity. This muscle group would have no purpose unless the entire group of muscles of inspiration was already working. The expiratory group is also composed of many muscles, attached to a different set of bones of the skeleton, and also must have precise size, location, directional orientation, quantity, timing, and force of contraction.
The expiratory muscle group is composed of many components. The inspiratory muscle group is composed of many different components. Neither group could have evolved without the other group already present because there is no purpose to breathe out if you can’t breathe in. In addition each group could not have evolved independently because each group has so many components that only have a purpose or function if the other parts are also present. Remember also that this is only sets of muscles that operate as a system to either breathe in or breathe out. This is within the larger system that also needs the systems to sense the need to breathe, the systems to exchange oxygen and carbon dioxide across the lung, and the systems to transport oxygen and carbon dioxide back and forth from the lungs to the cells.
Of course even breathing in and out is not this simple. We have discussed the elastic fibers in the lung and chest wall that act during expiration of quiet respiration. These fibers only account for one third of the recoil tendency of the lung. The other two thirds of the recoil tendency are caused by surface tension of the fluid lining the lung. There is an attraction between molecules through electrostatic forces that creates surface tension. This is why it hurts to do a belly flop into a pool. The forces between the molecules on a surface of a liquid can be quite strong and thise forces between molecules on a surface of a liquid can be quite stronggkkk causes a continual tendency for the lung to collapse. It is extremely powerful and breathing in would not be possible against this force without the presence of surfactant. Surfactant is a chemical made up of a precise mixture of fats and proteins that is secreted by special cells in the surface of the lung. Surfactant decreases the surface tension of the fluid lining the lung because of its effect on the force of attraction of all the other molecules that are at the lining of the lung. It is so important that infants born with cells that do not make enough of this surfactant die because they cannot breathe. This is called hyaline membrane disease or respiratory distress syndrome. All the other aspects of breathing would be useless and breathing not possible without surfactant. Surfactant itself is so specialized and is secreted only by cells that are present in the only location that would allow it to work. The way it works is is through complex changes in the force between liquid molecules on the surface of the lung by making a single layer of molecules throughout the surface of the lung. In addition, the lung membrane is folded on itself extensively so there is enough surface area for respiratory gas exchange. The surface area of the lung is about the size of a tennis court, completely covered with a single layer of molecules of surfactant, secreted by specialized cells in the only place that would make the system work. Without surfactant human life would not exist.
Breathing also requires the movement of air through the respiratory passages. The first part of this is the nasal cavities. Here air is warmed, humidified and filtered. Like the surface of the lung, the surface of the sinuses in the nose is extensively folded to increase the surface area. The passage of air over this large area of the turbinates warms and humidifies the air before it goes to the lungs. The temperature rises to within 2-3 percent of body temperature and is humidified to within 2-3 percent of full saturation with water vapor in the sinuses. Some people have a medical condition that requires surgically bypassing the sinuses and a tracheostomy is placed. This is a hole in the neck which connects directly to the trachea. These people do not benefit from the function of the sinuses and the air is cold and dry and which leads to serious lung crusting and infection. The air is also normally filtered in both the nose and in the lung. As the air passes through the turbinates the air hits multiple obstructions because of the extensive folding of the surface. The particles suspended in the air cannot change direction of movement as quickly as the air and strike the surface of the turbinates and are filtered. All the surfaces of the nose are covered with a thin layer of mucous that traps these particles in the air. The surfaces of the nasal passages are covered with tiny microscopic hairs called cilia. These cilia move in a coordinated pattern that moves the sheet of mucous with the embedded filtered particles. Each individual microscopic cilia moves like a choreographed dance with adjacent cilia so that the combined movement of these hundreds of thousands of hairs is able to filter the air we breathe. It is so effective that no particles in the air larger than a red blood cell, or 4-6 one millionth of a meter, get past the nose. There are further filtration mechanisms deeper in the lung for particles smaller than this that are removed by a system of other types of fluids lining the surface of the lung as well as the immune system. All the these structures that perform the functions of warming, humidifying and filtering the air, as intricate as they are, are only another system within the system that just moves air into the lung within all the other systems required for breathing.
The processes that produce speech also involve these air passages and this portion of the respiratory system. The vocal cords are folds in the walls of the larynx at the top of the trachea. There are tiny muscles within the larynx that position and control the degree of stretch of the vocal cords. The physics of the air flow over the vocal cords cause them to vibrate and produce sound. The pitch of the sound is adjusted through frequency modulation and articulation is accomplished with use of the lips, tongue, and soft palate. The mouth, nose, sinuses, pharynx, and chest cavity add the resonance quality of speech. Speech involves other systems in addition to the respiratory system such as specific speech control centers in the brain. Speech is composed of two separate mechanical functions, phonation with the production of sound in the larynx and articulation to create specific patterns of sound we recognize as speech which is achieved by the structures in the mouth. Speech itself is an example of intelligent design with systems operating in conjunction with other systems to perform a function, and all of this integrated with the air passages of the respiratory system. Of course speech would have no use without hearing and it is quite amazing that vibrations of folds in the larynx can vibrate the molecules in the air and that these vibrations are transmitted far enough in air to be detectable by the ear. The ear is so sensitive to be able to detect these miniscule air vibrations and all the systems in the ear to detect sound is integrated with centers in the brain which can recognize and interpret this as speech. The systems in the brain for sound recognition have no purpose without the systems in the ear for sound detection and both have no purpose without all of the systems that produce sound as speech that is only one part of the respiratory system where the purpose for breathing is unrelated to production of sound. The human body is truly a marvel of systems within systems within systems and all of these working together, simultaneously and mutually dependent. There is layering of complexity of detail in all of the organs systems in the human body that cannot be the result of undirected random chance mistakes. The degree of complexity and the vast number of interrelated systems must have been created by God.
Figure 1: The Respiratory Passages
Respiratory gas exchange is the next process in the act of breathing. The oxygen that we breathe in and the carbon dioxide we breathe out are both gases that must be transported across the respiratory membrane. The beauty of this portion of the respiratory system is in the structure or architecture of the lung. Let’s follow the air passages to where respiratory gas exchange occurs. The atmospheric air is brought into the body by the creation of negative pressure by expanding the lung as has been described. The air flows through the mouth and nose, past the larynx, into the trachea which divides into right and left mainstem bronchi. These begin to branch and divide into progressively smaller units called bronchioles. The appearance is rather like the the stems of a cluster of grapes. These continue to divide and distribute the air into smaller air passages. The end of this system is the respiratory unit. The tiny terminal bronchioles are connected to alveolar air ducts. The alveolus is a sac of air so tiny that there are about three hundred million of them in the lung. The surface of the lung here becomes so thin that oxygen and carbon dioxide can get across into the blood. The physiology of this respiratory gas exchange is quite complicated involving principles of physics such as partial pressures of gasses, the vapor pressure of water, and diffusion coefficients. All of this could not happen if the anatomy and structure was not perfect and precise. The vascular system has a similar extensive branching pattern. These blood vessels become so small at the level of the alveolus that each red blood cell has to squeeze through the smallest vessels called capillaries so the membrane of the red blood cell touches the wall of the capillary. This facilitates the transport of carbon dioxide from the blood into the alveolus and oxygen from the alveolus to the blood. If these capillaries were larger the respiratory gases would have to pass through all the liquid in the blood called serum before they could enter and exit the red blood cell. If the capillaries were any smaller the red blood cells would not pass through at all and we would die as no oxygen would be delivered to the cells. It is the contact of the membrane of the red blood cell with the wall of the capillary which is next to the alveolar air sac that allows for this respiratory gas exchange to occur. The dimension of the capillaries is perfect; we could not live if they were bigger or if they were smaller. This fact is demonstrated in disease states such as interstitial edema and pulmonary fibrosis. These diseases can be fatal because there is extra fluid or fibrous tissue at this level of the capillary that impairs respiratory gas exchange. All of the diseases that have been used as examples of what happens when the body does not work normally show the delicacy of the balance between life and death and how specific and precise each portion of every system has to function. Even when every part of every other system works perfectly, having just one part of only one subsystem not work exactly perfectly make the entire process not function and life would be impossible.
The number of capillaries contained in the walls of the alveolus, along with the spacing, size, distribution and blood flow combine with the spacing, dimension and distribution of air flow to allow for respiratory gas exchange. The physics and physiology of these processes would not be possible without the structure. The initial branching of both the air passages and the vascular system would have no purpose without the final structure at the level of the capillary and the alveolus. The trachea has no purpose without the bronchi, which have no purpose without the bronchioles, which have no purpose without the alveolar air ducts which have no purpose without the alveolar air sac. There is no purpose for any of these physically connected structures until they branch all the way down to the microscopic level. The same is true for all of the branching of the vascular system to the microscopic capillaries. Neither the alveolus nor the capillaries have purpose without the other. Respiratory gas exchange can only occur at the respiratory unit. If the vascular system did not divide so frequently, extensively, and to such a small size, all contained in the walls of the alveolus which has also divided equally extensively, breathing would not be possible.
However, the structure of the lung contains more than just air passages and blood vessels. There is also a nervous system contained in the lung. These nerves are a separate portion of the nervous system from the nerves discussed to allow for inspiration and expiration. Those nerves that signal muscles to contract are motor nerves whereas the nerves in the lung are autonomic nerves. The autonomic nervous system has sympathetic and parasympathetic branches and the lung has both. Stimulation of the sympathetic nerves in the lung causes the air passages to become larger, called bronchodilatation and the blood vessels to become smaller called vasoconstriction. Parasympathetic stimulation causes the opposite; bronchoconstriction and vasodilatation and also an increase in secretions from the glands in the lung. These changes mediated by the autonomic nervous system modulate the function of the lung in times of stress, exercise, rest or infection. There are also lymph vessels in the lung which are part of the immune system containing specialized cells located in lymph nodes that are able to fight infection. This lymph fluid of the immune system is connected into the vascular system. The lung itself is an organ but contains portions of many other organ systems. The air passages and vascular system is integrated with the immune system and nervous system. Each of these systems is immensely complicated in themselves, but they all work together to perform this specific function of respiratory gas exchange.
Remember for evolution to be true each change must make something useful. Living systems could not have evolved because there is no use for any one system. There is no reason to be able to sense the need to breathe, or to be able to send signals to breathe, or have the muscles and bones to be able to breathe, or have the passages for air or the vessels for blood if the oxygen and carbon dioxide cannot be transported in the blood. All of the mechanisms of the respiratory system that have been described only result in the movement of air into and out of the lung. Even if all of these systems were in place and functioning perfectly they would still have no use because the end result of all that has been discussed is only an interface of air with the vascular system. The next system that is needed is a method to deliver the oxygen to the cells and remove the carbon dioxide from the body that is produced from the cells.
There are trillions of cells in the human body. A trillion is a million million. Each cell uses oxygen and produces carbon dioxide. To stay alive oxygen has to be delivered to each cell at the rate it needs and and carbon dioxide must be removed. The red blood cells can be thought of as little red trucks that transport the oxygen and carbon dioxide. There are approximately 25 trillion of these trucks in an average adult. Each truck is equipped with or contains hemoglobin. Hemoglobin is the molecule that binds oxygen and carbon dioxide inside the truck for transportation. Each of the 25 trillion red blood cells contains 250 million molecules of hemoglobin. Each red blood cell is capable of carrying a least 1 billion molecules of oxygen. So the oxygen carrying capacity of all of the red trucks is 25 trillion billion molecules of oxygen. The trucks do not last long and need to be replaced frequently. Each red blood cell lives for only 120 days and then is destroyed in the liver and spleen. Then another 25 trillion red blood cells containing another 250 million molecules of hemoglobin each is made to replace the aging fleet.
The red blood cells are made in the center, or bone marrow of the skull, ribs, vertebrae, and in the ends of the long bones. The production of red blood cells is controlled by a hormone called erythropoietin. A hormone is a chemical substance produced in the body that controls and regulates the activity of certain cells or organs. This hormone is more complex than many as a precursor for erythropoietin is made in the liver, changed in the kidney, and then is able to stimulate the production of red blood cells in the bones. This coordinated working of the liver, kidney, spleen and bone marrow only results in the ability to produce and destroy the red trucks. Here we see these four separate organs are involved in the functioning of red blood cells, and this is only one portion of the entire process of respiration. This is another example of systems within systems within systems. But this is just the trucks. It is the hemoglobin in the trucks that carries the oxygen and hemoglobin is far more complex.
The hemoglobin inside the red blood cells is a chemical of structural beauty. Each molecule of hemoglobin is a made of 4 chains of proteins with heme, an iron containing group at the center. These are all grouped together and maintained in a specific shape by molecular bonds. The four chains of proteins are two alpha chains and two beta chains. The alpha chains contain 141 amino acids and the beta chains have 146 amino acids. They are balled up and packed together so that small changes in the shape will allow the loading of oxygen in the lung and unloading of oxygen when the red blood cell arrives at cells that need the oxygen. It is incredible that these chains, like all proteins are made of only 20 types of amino acids. The amino acids are connected end to end in chains to make all the different types of proteins and changes in the order of the amino acids in the chain is what determines what the protein will do. The alpha and beta chains of hemoglobin are only 2 of more than 100,000 different proteins identified in the human body.
The order or sequence of the amino acids is called the primary structure and is determined by the coding in DNA. This is the order of the amino acids as they are bonded together in a line. The long chain will fold and coil after assembly because of chemical and molecular bonds and interactions among and between all the amino acids in the chain. This is called the secondary structure of protein when the amino acid chain coils or folds in a particular, consistent and reproducible way. There are also tertiary structures of proteins when these folded and coiled chains ball up into globular and rounded shapes. The tertiary structure is made by additional types of bonds between the atoms of the chain called hydrogen bonds, ionic bonds and covalent bonds. When more than one chain is grouped together with others, such as in hemoglobin, this is called the quaternary structure. It is this final shape of the protein that allows the protein to perform a function. If the shape is not exactly perfect, the hemoglobin will not be able to transport oxygen.
There are many examples of diseases where proteins do not function correctly and these demonstrate how impossible it would be to get this system by chance mistakes. The primary structure which is the sequence of the amino acids in the chain determines the ultimate 3 dimensional shape of the protein. All of the subsequent folding, coiling, balling, and bonding is always exactly the same once the initial order is completed. The disease sickle-cell anemia is a disease where only one amino acid of the 146 on the beta chain is incorrect. This is an extremely painful and debilitating disease where the hemoglobin does not carry oxygen correctly. All of the other 145 amino acids are correct on the beta chains of hemoglobin and all of the 141 amino acids on both alpha chains are correct in people with sickle-cell anemia. If just one amino acid is placed incorrectly the ultimate shape is affected and the protein does not work correctly.
The existence and functioning of proteins is an interesting example of the intelligent design argument. Because the primary structure determines the secondary, tertiary and quaternary structures it is the initial order of the amino acids that can be understood as the basis for a system to operate. These two proteins of hemoglobin are only 2 of the more than 100,000 proteins. Each protein has similar probabilities of random chance sequences to make a functional protein. Within the framework of intelligent design we know that systems function within and are dependent upon other systems. To this we now add the problem that all of these systems have proteins as components. The 100,000 different types of proteins are all made up of long chains of amino acids and perform many different type of functions. Hemoglobin is an example of the transportation function since it carries oxygen and carbon dioxide. Other proteins also have transport functions such as the channel and carrier proteins in the membrane of every one of our trillions of cells that allow substance to enter and exit the cells of the body. Also in the membrane of each cell are more than 100,000 receptor proteins that act as switches to signal to the cell what is in the environment near the cell. Another function of proteins is structural support such as the proteins in tendons, ligaments and skin. Enzymes are also made of proteins and are essential for life because they speed chemical reactions in the body. Our immune system uses antibodies for defense and these are also made of proteins. Hormones are regulatory proteins that serve as intracellular messengers to control metabolism of cells. Our muscles that allow us to move are made of the contractile proteins actin and myosin. Proteins that function in these roles as structural support, enzymes, transportation, receptors, immune defense, hormones and movement are all part of systems dependent upon other systems that also have many proteins. Even if one protein did ‘evolve’ by this exceedingly remote probability it would be useless unless a multitude of other proteins in other dependent systems also simultaneously and randomly were produced.
This aspect of proper sequencing by chance is actually far more complicated than this. The probability calculations are based on already knowing how many amino acids are needed in each protein. If there are extra or missing positions the protein will not be useful. The evolutionary model has not presented a theory on how this information of the number of amino acids that is required in each protein developed where every protein has a different number of amino acids. We now know this information is in the DNA. It is the instructions in the DNA that is really at the core of creation, as is discussed in detail in the section of DNA as a mechanism of change. For now, just be aware that evolution does not even have a theory to explain the origin of DNA.
The aspect of DNA that is more specifically related to intelligent design is protein synthesis. So far, we have only discussed the order of the amino acids in a protein. This order is determined from codes in the DNA. Of course this coding for the proper sequence of amino acids in the DNA is in itself immensely complicated; however the process which assembles amino acids from these codes is even more complicated and is called protein synthesis. You see, proteins do not self assemble from a pool of amino acids; they need to be built in the correct order. In the process of breathing we are focusing on oxygen transport by proteins in hemoglobin contained in red blood cells. Now let’s consider the process that makes protein from the information in DNA, the process of protein synthesis.
There are genes within our DNA with the instructions for how to make hemoglobin. The expression of this gene that results in the production of hemoglobin requires two steps. First, during transcription DNA serves as a template for the formation of RNA, or ribonucleic acid. Second, during translation RNA directs the sequence of assembly of the amino acids to make a protein.
Figure 2: Transcription
During transcription the tight double helix of the DNA unwinds and unzips so that a portion of the DNA bases are exposed. Another complex protein called RNA polymerase is able to detect where the gene starts by the sequence of DNA bases in a promoter region. The RNA polymerase then begins to synthesize, or transcribe, a long strand of messenger RNA that is made of bases complementary to the bases present in the DNA. This complementary strand is possible because each base of the DNA has unique bonding so that each base of the unwound and unzipped DNA can only bond with one type of base in RNA. As all these bases of RNA are attached end to end a long strand of messenger RNA is produced. This transcription continues until the RNA polymerase comes to a stop sequence on the DNA and the messenger RNA is released. This process occurs in the nucleus of a cell which contains the DNA. The nucleus is separated from the rest of the cell by a special nuclear membrane and this messenger RNA must then be transported out of the nucleus through a specialized nuclear pore complex to the cytoplasm of the cell where the protein will be assembled in the process of translation. The process of transcription to have the DNA unwind, then unzip to expose the interior bases, the RNA polymerase’s ability to identify where to start and stop transcribing, the unique complementary base pairing of the DNA and messenger RNA, and the mechanisms to attach all the RNA bases end to end to make the long messenger RNA strand would be useless if the messenger RNA could not be transported through the nuclear pore complex, which itself is made of many proteins and has the ability to both recognize that messenger RNA has been made and also has the ability to transport RNA out of the nucleus which is only one part of the cell and is isolated by the nuclear membrane.
The process of assembling a protein from individual amino acids from the messenger RNA is called translation. The messenger RNA is an extremely long strand of bases connected end to end. The ‘part’ that assembles amino acids from messenger RNA is ribosomal RNA which itself is, of course, made of many other parts. The components of ribosomal RNA are also made in the nucleus being transcribed from other portions of DNA and are also transported to the cytoplasm. They are packaged with a variety of proteins into the final structure called a ribosome. There are thousands of ribosomes in each cell because these are what make proteins and there are so many types of proteins (more than 100,000) that do so many different things.
Figure 3: Ribosomes
The three steps of translation are initiation, elongation and termination. Initiation is the step that brings all the translation components together. The messenger RNA is the long strand of RNA bases. Every three bases in a row are called a codon. Near one end of the messenger RNA is a set of three bases called the start codon. This start codon attaches to the ribosome at one of the three attachment sites on the ribosome. The final part that is needed is transfer RNA. Transfer RNA is a long strand of RNA that folds and balls up to a shape that has an anticodon end and an amino acid end. The anticodon end is made of three bases in a row that are complementary to three bases in the messenger RNA. The sequence of bases in the messenger RNA will have a variety of sets of possibilities for these three bases of a codon. Every codon is made of only three bases of RNA. For every possibility of the order of the three bases in a codon there is a transfer RNA that will match it. The anticodon end of each transfer RNA is specific for the codon of transfer RNA. The other end of the transfer RNA is the amino acid end and will carry one of the 20 amino acids to the ribosome.
Figure 4: Transfer RNA
This is complicated so let’s review. The DNA has a sequence of DNA bases called a gene that will code for the protein hemoglobin. The DNA is unraveled from the helix and an RNA polymerase is able to make a complementary messenger RNA strand. The order of the bases in the RNA strand is determined by the order of the bases in the DNA. It is like an inverse copy of the DNA. The messenger RNA is transported through the nuclear pore complex from the nucleus to the cytoplasm of the cell. This completes transcription. Translation begins with the attachment of messenger RNA to a ribosome at the special sequence of 3 bases called the start codon. Every 3 bases in the chain after the start codon is another codon. Each codon on the messenger RNA matches an anticodon end of a transfer RNA. The other end of each transfer RNA carries one of the 20 amino acids.
Figure 5: Translation Initiation
At this point the initiation step of translation is complete. There is a long strand of messenger RNA that has been copied from DNA and is attached to a ribosome. So far only the initial transfer RNA that brought the first amino acid to the ribosome is attached to the ribosome at the start codon. The next step is elongation where the protein will be assembled by connecting amino acids one at a time. The order of the amino acids is set by the order of the bases on the messenger RNA. Every 3 bases on the messenger RNA is a codon and matches the anticodon end of a transfer RNA which brings the next needed amino acid to the ribosome. After the first transfer RNA is brought to the start codon of the messenger RNA on the ribosome it is shifted to the second binding site on the ribosome and the next codon of messenger RNA is in the first binding site of the ribosome. This allows space for another transfer RNA to come that has the anticodon matching the next codon of messenger RNA. There are now 2 transfer RNA’s on the ribosome. Each transfer RNA brings an amino acid and only now can the two amino acids be connected.
Figure 6: Translation Elongation
The way they are connected is another subsystem of complicated chemical reactions using multiple components. The result is the beginning of a chain of amino acids. The first transfer RNA then shifts to the third binding site of the ribosome and is released. The second transfer RNA is then shifted to the second binding site and now has two amino acids connected it. A third transfer RNA will bring the next amino acid to the first binding site and this process is repeated. After the next cycle, the second transfer RNA will be released from the ribosome and the third transfer RNA will be in the second binding site with 3 amino acids and the first binding site will be open. The first binding site has the next codon, which is the next sequence of 3 bases that will code for the next amino acid. During elongation, amino acids are added one at a time to a growing chain that will make hemoglobin. Termination is the final step that ends translation when a stop codon is recognized in the messenger RNA and the entire protein chain is then released.
Figure 7: Translation Termination
Hemoglobin is made in this way. The gene in the DNA is copied to make messenger RNA. The messenger RNA is bound to a ribosome. The ribosome can connect one amino acid at a time as it moves the messenger RNA to different binding sites. Transfer RNA brings specific amino acids to the ribosome to assemble the long chain to make the protein. The order of amino acids is determined by the order of the bases on transfer RNA which was determined by the order of the bases on DNA. Of course all of this activity must be regulated which hasn’t even been discussed.
It is the regulatory function that gets ridiculously complex. Genes don’t just turn on and off on their own. There are separate processes to determine when hemoglobin is needed, when it is not, and how much to make. This regulatory process is an entirely separate system that is integrated with the protein synthesis process. The regulation of gene activity and the methods cells use to perceive the environment and control gene activity is not yet well understood. We know that some of the 100,000 proteins in the membrane of each of the cells in the bone marrow can recognize the hormone erythropoietin and there is signaling to produce red blood cells. Remember a precursor for the hormone erythropoietin is made in the liver, changed in the kidney, and only then is able to stimulate the production of red blood cells in the bones. Part of the production of red blood cells is the synthesis of the hemoglobin. However, do not confuse the more than 100,000 proteins in the cell membrane of each cell with the more than 100,000 different types of proteins. Only some of the types of proteins are in cell membranes, the other types are involved in structural support, enzymes, transportation, immune defense, hormones and movement. Of the cell membrane proteins, some are receptors which are able to sense the environment such as the presence of hormones like erythropoietin and then signal the nucleus to control gene expression through other regulatory proteins, ultimately producing hemoglobin.
The hemoglobin that is made must have the perfect order of the amino acids to be able to bind oxygen correctly. There is a group of diseases called thalassemias that shows how all this can go wrong. Some of the thalassemias have less genes in the DNA for hemoglobin, others have too many and make the alpha chain with 172 amino acids rather than 141. Others have problems with the initiation step of translation while others terminate the chain too early at the ribosome. Still others make enough alpha chains but not enough beta chains. This is a horrible disease caused by mutation of the DNA with no cure and some people need to have blood transfusions every 2 or 3 weeks for the rest of their lives, many getting AIDS as a result of treatment. The level of precision that is required in each of these steps to make hemoglobin, and the understanding of how all of this is just to make hemoglobin which is only one small part of the whole process of respiration produces a sense of awe of the all powerful God who can create life and how all of this interrelated complexity could not have occurred by random chance alone.
Figure 8: Hemoglobin
The hemoglobin molecule is very complex with 2 alpha chains, 2 beta chains and a heme group in the middle. The alpha and beta chains are made by this process of protein synthesis which has multiple steps, using multiple other structures, and the assembly is done is various locations in the cell. Hemoglobin could not be produced if all of these parts did not work together. But no one part could have ‘evolved’ by itself because each part has no use by itself. All of these parts only have a use if all of the other parts are present. So there is no way to get the first part or any other part. Some of the parts of this system to produce hemoglobin are: DNA, RNA polymerase, promoter, messenger RNA, ribosomal RNA, transfer RNA, nuclear pore complex, ribosome, codon, anticodon, and amino acids. Each of these has no use without the others, each is complex in itself, and all of this only produces hemoglobin, which is only one part of the red blood cell which is only one part of the vascular system. And the vascular system is only part of what is required to bring oxygen to the cells if all the other parts of the respiratory system that sense the need to breathe, or to be able to send signals to breathe, or have the muscles and bones to be able to breathe, or have the passages for air to bring oxygen into the body work correctly.
The final step in respiration is the delivery of oxygen to the cells and transportation of carbon dioxide from the cells to the lungs. This is controlled by the binding of oxygen and carbon dioxide to hemoglobin. Everything explained so far would have no effect or purpose if the hemoglobin could not pick up oxygen in the lung and leave it at the cells and pick up carbon dioxide from the cells and drop it off in the lungs. There is no use in the ability of hemoglobin to carry oxygen and carbon dioxide if there is not the timing of when to load and unload. If hemoglobin is able to carry oxygen but the red trucks don’t load it up in the lung it is of no effect. If it is able to carry oxygen and able to load it in the lungs but is unable to unload the truck to deliver oxygen where it is needed it is also of no effect. The same is true for the timing and location of pick up and drop off of carbon dioxide. Hemoglobin must not only be able to carry carbon dioxide, it must be able to pick it up at and only at the place it is produced and not unload it until and only at the lung. This timing is governed by principles of physiology.
The loading of oxygen in the red truck is studied as oxygen binding and the unloading is controlled by oxygen dissociation. The dissociation of oxygen with the hemoglobin molecule delivers it to the cells. Oxygen binds to the heme portion of hemoglobin and this is an extremely loose bond that is easily reversible. The amount of oxygen in a portion of the body is described as the partial pressure. This term is used because oxygen is a gas and the physical properties of gasses are pressures. It is the partial pressure because other gasses are also present contributing to the total pressure. In the lung the partial pressure of oxygen is high and oxygen is bound to heme. In the tissues the cells have used the oxygen and the partial pressure is low and oxygen is released from heme. There are chemical properties that determine the ability of heme to bind oxygen, and how amazing that these chemical interactions are just perfect so that oxygen is able to bind to heme in the lung where needed. Slight changes in the partial pressures of oxygen that are required for binding would prevent the existence of life. The chemical properties of heme are perfect to allow for life. In the same way if heme could not release oxygen at lower partial pressures the red trucks would flow past the tissues and cells and never unload the oxygen and again there would be no life. The dissociation of oxygen from hemoglobin delivers oxygen to the cells. The binding and dissociation of oxygen is also an active process that changes with the needs of the body. The partial pressures that both bind and dissociate change with exercise, acidic environments and when the oxygen is low in the atmosphere such as high altitude. When these conditions are present more oxygen can be delivered when it is needed because there are changes in the physical properties of hemoglobin that result from chemical changes in the blood that are recognized by the heme molecule as an increased need for oxygen by the body. The precision and flexibility at this tiny chemical level is amazing.
Carbon dioxide is transported in the blood in three different methods. Some of it is bound to hemoglobin to form carbaminohemoglobin and is transported in a similar way as with oxygen. This accounts for 23% of the carbon dioxide. A minor amount, just 7% is dissolved in the fluid of the red blood cell. The main method is in the form of bicarbonate and accounts for 70% of the carbon dioxide. This balance and chemical conversion between carbon dioxide and bicarbonate is the same as was discussed in the brain that stimulated the act of breathing.
Remember the inspiratory center with the chemosensitive area which can sense the concentration of hydrogen ions in the blood? As carbon dioxide builds up in the blood it crosses the protective blood brain barrier and then undergoes a chemical reaction with water mediated by the the enzyme carbonic anhydrase to make bicarbonate and hydrogen ions. These hydrogen ions then initiate the sequence of events that signal the chemosensitive area to trigger the inspiratory area to send the signals to take another breath. So the production of carbon dioxide by the cells is released into the blood, chemically converted to hydrogen ions in the cerebrospinal fluid, sensed by the chemosensitive area which stimulates the inspiratory center to take a breath that will eliminate carbon dioxide through the lungs.
This same enzyme carbonic anhydrase that is so critical in the brain for control of respiration is also present in the red blood cell. This enzyme is another protein so the red blood cells ability to know when to make it, how much to make and the process of protein synthesis is exactly like the discussion with the protein hemoglobin. The importance of carbonic anhydrase has been measured experimentally in animals by giving a drug that blocks this enzyme in the red blood cells and the transport of carbon dioxide from the tissues is so poor that the animals would die if it was not reversed. The presence of carbonic anhydrase in the red blood cell converts carbon dioxide to bicarbonate and this is the main way carbon dioxide is transported from the cells to the lungs and without it none of the other aspects of all of the other systems of respiration would benefit us because we would not survive.
This study of oxygen and carbon dioxide emphasizes the balance of all of life. The fact that we depend on oxygen to live and that it is produced by plants and that plants depend on carbon dioxide to live and it is produced by us is another astonishing fact that defies evolutionary coincidences. The oxidative metabolism of animals uses oxygen and produces carbon dioxide. The photosynthesis reactions of plants use light and carbon dioxide and produce oxygen. We typically live our lives without an awareness of the connectedness of life and the exquisite beauty of creation.
The oxygen produced by the plants is transported to our cells by hemoglobin. The protein portion of the alpha and beta chains has already been described. However the portion of the molecule that actually carries the oxygen is the heme in hemoglobin. The formation of heme is the product of yet another set of complex biochemical reactions. In the intelligent design logic we know that the systems that produce heme only function to support the other systems that make hemoglobin which is only a part of the red blood cell which is only part of the vascular system which is only part of the system for respiration.
The structure of heme is a complex combination of organic and inorganic atoms. The synthesis of heme involves many chemical reactions which are beyond the scope of this book. They are listed to give an appreciation of the complexity and detail that is required, and is an example of the chemical basis of all the systems previously described. The heme portion of hemoglobin is produced in a compartment of the red blood cell called the mitochondria. Synthesis begins with changing acetic acid to alpha-ketoglutaric acid in the Krebs cycle. This is combined with glycine to form a pyrole compound. Four pyrole compounds combine to form a protoporphyrin compound. One type of protoporphyrin, protoporphyrin III, then combines with iron to form heme. Four heme molecules then combine with the protein to make hemoglobin. A number of other substances act as either catalysts or enzymes during different stages of this biochemical sequence. These include copper, pyridoxine, cobalt, and nickel. This listing is presented to emphasize the fact that hemoglobin formation results from a series of synthesis reactions, where each step of the reactions needs multiple building materials and each step is controlled by other materials that function as catalysts or enzymes. As always the logic of intelligent design is that every step depends on other steps and this heme synthesis is just another example of layered complexity.
Figure 9: Chemical Structure of Heme
Another interesting point with hemoglobin is that there are three types of hemoglobin. Even if all of these interrelated and complicated biochemical pathways that produce adult hemoglobin did occur by chance, it would again be useless. This is because infants must have fetal hemoglobin which is different than adult hemoglobin. For the fetus to develop inside the mother the mother must deliver oxygen to the fetus through the placenta. If the mother and the fetus had the same hemoglobin there would be no transfer of oxygen to the fetus, the fetus would die and there would be no next generation to inherit all of the marvelous biochemical engineering that makes adult hemoglobin. Fetal hemoglobin is special in that it is able to take oxygen from the adult hemoglobin of the mother as the blood passes through the placenta. This transfer of oxygen from the mother to the fetus would not happen if they both had adult hemoglobin. The fetus must have different hemoglobin to survive. This is possible because fetal hemoglobin has a different structure which changes the principles of physiology for oxygen binding and dissociation. Rather than 2 alpha and 2 beta chains, fetal hemoglobin has 2 alpha and 2 gamma chains. The gamma chains are also a chain of amino acids like the alpha and beta chains. It is coded from a separate gene on another chromosome in DNA. The gamma chain code is on chromosome 11 and the alpha chain is on chromosome 16. There is actually a third type of hemoglobin, embryonic hemoglobin which is present in the fetus only for the first 10 to 12 weeks. Fetal hemoglobin is present after this time and is no longer useful, even harmful after birth. The genes that produce fetal hemoglobin are deactivated while the genes that produce adult hemoglobin are activated. By 6 months no more fetal hemoglobin is present. This transition from embryonic hemoglobin to fetal hemoglobin to adult hemoglobin is essential for a fetus to develop. Without each one present at the proper stage of development no changes that might have produced adult hemoglobin would ever survive to further generations. There are additional signaling systems, coded in other genes that regulate when each of the genes that produce these 3 hemoglobins need to be activated. The timing of the activation of each gene is perfect so the correct type of hemoglobin is made at the time it is needed in the development of an individual. Each hemoglobin is unique, structurally different, and is coded on different chromosomes of the DNA, having specific properties for the binding and dissociation of oxygen, and each is made at specific times of development controlled by different signaling systems. All of these systems within systems are within the system of oxygen delivery within the respiratory system.
The discussion of embryonic and fetal hemoglobin leads to a fascinating truth about the development of the vascular system. The vascular system of the developing fetus is structurally different than after birth because of the need to get oxygen from the placenta rather than the lungs and then must change after birth to be able to get oxygen from the lungs as the placenta is no longer there. In the fetus only 12% of the blood flows through the lung, the air sacs are closed and the lung is full of amniotic fluid. After birth there must be immediate changes to allow for the baby to get oxygen from the lung. The transition from fetal circulation to adult circulation that occurs at birth is nothing short of a miracle created by God. The perfect timing and coordinated changes in multiple structures during this transition is largely unknown to those without a medical education and vastly unappreciated by those who do not know Jesus made it all. This is all begins at the instant of birth as I witnessed many times in my career as an anesthesiologist. The infant must perform these transitions perfectly or life will not continue.
It begins with a tremendous force by the infant to open the lungs for the first time. Changes in the flow of blood must then occur to have the blood flow through the lung to get the oxygen. In the developing fetus the blood flows through three passages that will no longer exist after birth. These fetal blood passages are the foramen ovale in the heart , the ductus venosus that bypasses the liver in the fetus, and the ductus arteriosis that had connected the blood flowing through the lung to the blood flow to the rest of the body. All three of these passages exist in the fetus to allow delivery of oxygen from the mother to the fetus through the placenta. They all now close to transition to the way the baby will get oxygen from the lung. These changes are within different parts of the vascular system, the arterial system, the venous system and the heart. This is an example of multiple changes in separate portions of the vascular system that must happen at a coordinated time for the respiratory system to begin to function. Even if all of the systems within systems that make up the entire respiratory system are working, there would be no life without the transition from the fetal circulation of blood. The interesting part here is that all of these systems must have been developed for a future need since the fetus had developed to the point of birth without ever using any of the respiratory system. In evolutionary theory there would be no part of any system that would evolve if it did not have use, and here the entire respiratory system must be developed without ever having been used.
We have seen how the respiratory system works in concert with the muscular system, skeletal system, neurologic system, immune system and vascular system. There are also functions of the lung to maintain proper acid base balance and this works with the renal system or the kidneys. The acid base balance of the body is tightly controlled to maintain a body pH of 7.4. All chemical and enzymatic reactions happen at rates that depend on the pH. Changes in the pH, or acid base balance, will dramatically change all the chemical reactions of the body. We see ourselves as physical beings but there is a chemical basis for all of our physical characteristics. We are essentially a vast collection of sequenced, ordered, compartmentalized, and interrelated chemicals. The way we maintain our pH for all this chemistry to work correctly is through buffering systems. There are other buffering systems in the body, but the lung and the kidneys are the most important.
This all involves the enzyme carbonic anhydrase again. Carbon dioxide combines with water to make carbonic acid which then dissociates into bicarbonate ion and hydrogen ion. It is the relative concentrations of the bicarbonate and hydrogen ions that determine the pH of the body. Because of the chemical reaction with carbonic anhydrase, the levels of carbon dioxide are related to the concentrations of bicarbonate and hydrogen ions. The respiratory system controls the body pH by maintaining, and altering when needed the levels of carbon dioxide in the blood. The kidneys, through completely separate and chemically intricate multiple systems, is able to excrete bicarbonate or hydrogen ions in the urine to adjust the concentrations of these ions in the body to maintain proper pH. When the body is too acidic it is called acidosis and when too basic it is called alkalosis. There can be changes in the body’s metabolism that cause either metabolic acidosis or metabolic alkalosis. Both of these problems are corrected by changes in the lung creating what is called respiratory compensation. The same is true when problems with the respiratory system cause respiratory acidosis or respiratory alkalosis. These problems are likewise corrected by the kidneys with renal compensation. These systems are interrelated in that there is renal compensation for respiratory acidosis or alkalosis and there is respiratory compensation for metabolic acidosis or alkalosis. All of this is closely monitored and functions to maintain the pH of the body so all the chemical reactions that are essential for life can work optimally.
All of this must also be considered with the realization that evolution teaches that we developed from fish. Fish use gills to get oxygen from water. This is an entirely different mechanism. There are no similarities. Fish do not have any of the processes for respiration. Respiration was presented as the integration of several separate processes. There are the inspiratory mechanisms, expiratory mechanisms, mechanisms of respiratory gas exchange, oxygen delivery mechanisms and the sensors to control and initiate these processes. Each of these individual systems would be useless to a fish and could not evolve. There is no point in having the chemical capability in portions of the brain that do not exist to sense carbon dioxide concentrations, or having neurologic connections to muscle that do not exist to expand a lung that does not exist, that does not contain respiratory unit which has no capillaries and no air sacs. The respiratory system at each and every level is entirely useless to a fish.
Let’s return to Darwin’s statement, “If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down.” It seems we have an answer! The respiratory system is a complex organ which could not possibly have been formed by numerous, successive (one at a time), slight modifications. To believe in evolution you would have to be able to present a sequence of individual changes from the gills of fish to the current respiratory system. You would have to be able to state specifically the first thing that changed is this, it is a very small change but it is an improvement that would give a survival advantage because of this. Then there was a second change that was a further improvement when this changed. The third change was this which was better because of this. This process or sequences of individual changes would have to go on and on until the respiratory system could function to get oxygen out of the air. This is impossible and even more impossible, if there are levels of impossibility, when each of these changes must be explained on a molecular basis and have DNA strands identified where each change is a random chance mutation. You would have to explain that this strand of DNA usually codes for this, there was a mutation here and that made this which makes a better fish but is really a step towards the development of a lung. Really!
And don’t think amphibians are going to give the answer you need to believe in evolution. A study of amphibians is equally mind boggling as the preceding explanation of respiration. Amphibians can also use their skin to take in oxygen and eliminate carbon dioxide. The stages of the tadpole development into a frog involve loss and gain of entire organ systems at stages of development after birth and all coded in DNA. The study of any living system just leaves you in awe of an all powerful God. The contemplation of life leads to a fresh understanding of Psalm 46:10, “Be still and know that I am God”.
To summarize, this evaluation of the human respiratory system finds that there is layered and embedded levels of complexity. Each portion of a system is made of multiple components with the value or use of each component defined by its usefulness within the system. Each each part is without individual use there is no reason for it to have been developed by itself. This directly contradicts the required sequence of evolution making evolution not possible. The theory states that without exception, each step of development must have created a new feature (by mutation of DNA) and that each step makes something better. The contradiction with intelligent design is that evolution necessitates only one change at a time and this is completely inconsistent with what we know about living systems. Living systems cannot be made by the sequential addition of parts when there is the requirement that each part must have usefulness prior to completion of the entire system. This truth is sufficient to reject the theory of evolution. We find that these systems must have been made and designed by God. It is the conclusion of the evaluation of the evidence.
This is the evidence of intelligent design. The evidence is presented based on scientific principles and facts. The evidence is separated from the implications. Scientist’s who believe in intelligent design are careful to present what can and cannot be said based on the science. It is clear there is an intelligent designer and life could not have been formed out of nothing as a result of random chance mistakes. The implication and result is that God exists. There is no opposing side to present. People who do not believe in intelligent design do not have another explanation. They can only say that with enough time they will be able to explain how these complex systems evolved, and acknowledge that at the present time they cannot explain them. They criticize intelligent design as not being scientific, but we know that neither creation nor evolution is a scientific theory. They do not have a hypothesis that can be tested and there are no repeatable experiments. Intelligent design, like evolution, is not a scientific theory but it is based on great science.
Take a deep breath!