Darwinian MedicineI just read a great book, “Why We Get Sick – The New Science of Darwinian Medicine.” It may change our understanding of medicine.
What better praise than from Richard Dawkins – “Buy two copies and give one to your doctor.”
E.O. Wilson – “…means for the improvement of medicine…fundamental new insights into the human condition.”
Robert Ornstein – “Every so often a book comes along that has the power to change the way we live and die. This splendid book is one, and it could well revolutionize the way Physicians are taught, the way they practice, and even the way parents watch over their child with a fever or cough.”
Let’s say you have a cold. You are running a temperature – you have the sniffles – you are coughing – you feel like shit.
What to do? Take some aspirin to lower your temperature and dull the pain, take an antihistamine to stop the runny nose, and take cough medicine to suppress the cough. Maybe not?
A million years ago, or whenever viral and bacterial infections first afflicted humans, the body had to evolve its own defenses. First, the body reacted by raising its temperature to make it more difficult for the virus to survive and multiply in the hot environment.
Second, mucous cells in the nose and throat went into high gear producing mucous to wash away viruses, bacteria, and dead cells. Sneezes aided in that function, by violently expelling excess, infected mucous and cells. In hunter gather groups, the spread of disease was limited, but large crowded cities increased the likelihood of the spread of infectious diseases, like influenza.
Third, sick feeling bodies then and now usually become inactive so that the sick will rest and recuperate. Ancient humans didn’t want to do anything but snuggle up under a bearskin robe next to a roaring fire.
Forth, mucous that dripped into the esophagus was swallowed and rendered harmless by stomach acid; excess mucous upset their stomachs so was expelled by vomiting. Mucous that dripped into the trachea was expelled by cilia cells beating upward. Accumulations in the throat were expelled by coughs.
Fifth, body defenses decided the digestion of big meals would sap energy that could be better used to fight sickness. What little food the body preferred was hot chicken or beef broth that loosened mucous and kept body temperatures, high. When the temperature rose too high, the evaporation of sweat lowed body temperature so it did not endanger heat sensitive brain cells. That was a million years ago; today we use modern medicine to help us in our misery. Unfortunately, modern medicine is too often misunderstood and misused.
Here is another example: Although sunburn today is easily treated and the skin seems to repair itself, millions of years ago excessive exposure to the sun’s ultraviolet rays routinely caused severe burns, sunstroke and dehydration in children. The result was the use of valuable and limited body energy and resources for fighting infection and promoting healing and recovery. It made survival sense that mutations that caused increased pigmentation prevailed in sunny climates. Today, humans with dark skin are protected from ultra violet light but those who migrate to northern climates with less sun suffer from lack of Vt. D., which led to the outbreak of rickets, a bone softening disease. Modern physicians wondered why, but by applying Darwinian medicine theory, they discovered the cause of increased rickets in blacks living in Scandinavian countries and encouraged the prescription of Vt. D to prevent the disease.
The authors tell of the infamous William Paley’s long debunked story about finding a pocket watch and inferring that because it had a designer, all life had to have a designer, thus proving the existence of God. The story is still used by Creationists. Here is the Darwinian version of the story: A man found a beautiful gold pocket watch with a precise, jeweled interior, with strong steel springs and a plethora of precisely made rustproof brass balance wheels, springs and cogs. But, this beautiful piece of creation did not work. A small defect let in moisture, and caused clogging rust; In addition, the rewind wheel had to be turned for too long and far to increase its running time for one second. True, the watch was beautiful but was not intended to last forever. Carefully etched on its back cover was, “Model 3,500,001,859 is designed to give accurate time. It will self repair most problems, except for those arising from manufacturing defects, novel environments or design compromises. In the ideal environment, its mean life span is 85 years. Care for it well, and enjoy it while you can. Lifetime Watch Company.”
Despite our body’s’ exquisite structure, it too has compromised design and crude flaws. Either evolution has not had time to perfect its design, or evolution has designed it to fail. There are genes that make us vulnerable to disease. There are also novel and recent factors that have occurred since our bodies were designed millions of years ago. For example, recent new design gradually made new behavior possible, such as walking upright, but it caused new problems with our spinal columns.
Evolution works as hard for our pathogens as it does for us. It works hard for predators and prey as they battle endlessly to evolve advantages over each other. Finally, our bodies do not have the luxury of throwing out the old and starting over. We must make due with what we have. The recurrent esophageal nerve runs a tortuous route down half the length of our bodies, looping around organs and vessels and then back up again for no apparent advantageous reason. The human eye is a nightmare of poor design and the common juncture of the esophagus and trachea make choking likely. A new design would have been desirable, but evolution does not have that design capability. It had to work with what it had and solve problems with existing material slightly moderated.
Neese and Williams predict future medical textbooks will include evolutionary explanations of why we get disease, why we age, and how we recover from disease. The authors ask and answer the following questions:
1 – Which manifestations of a disease are results of it and which are body defenses to the disease? A runny nose may be our body’s defense to get rid of pathogens, or it may be the pathogen’s method of getting expelled by a sneeze or cough to infect someone else? The answer may be, both. The winner of the battle is not yet determined.
2 – Why aren’t bad genes lost by evolution? Bad genes that do not affect our reproductive ability are not affected by natural selection and are retained, possibly to reappear in the future.
3 – Why do novel or sudden environmental changes cause disease? Rapid environmental changes happen too fast for natural selection to respond. Plantar fasciitis (heel spurs) are the result of extreme stress on the thick fascia that supports the foot. Darwinian medicine suspects the reason for this is the fact that modern humans sit more than they squat. Squatting stretches the fascia and is the reason societies that don’t use chairs do not suffer from the disease. Another example is AIDS. It long existed in primates but as overpopulation caused famine, primate protein became popular and invited the interspecies spread of mutated virus. Modernity facilitated the spread of this disease that other wise would have remained dormant in wild primate populations.
5 – What design compromises account for our susceptibility to disease? In order to enjoy the advantages of upright posture we evolved an unstable lumbar curve, which increased the risk of low back instability. Ancient dietary changes were needed, such as the need for increased protein to sustain rapid brain growth. The introduction of fire made food more chewable and digestible. Smaller teeth were required, and as the jaw shrunk to accommodate the new life style it crowded unneeded molars into oblivion, causing infection and even death. The dietary compromises apparently were worth the lives lost due to infection. Evolution has acted to make the genes responsible for a large jaw and wisdom molars recessive. More and more babies are born today minus this dentition.
Neese and Williams encourage research into Darwinian Medicine. The field, they say, is ripe for doctoral studies, as funds are made available. As I better understand Darwinian Medicine I see its importance to our health and well being. Doctors with this new knowledge will be able to examine patients and better understand the diseases they encounter. Doctors will be able to determine the cause of a disease and know how best to treat the disease. Medications should not be designed to defeat natural body defenses. Natural healing should be enhanced, not hindered. Cell regeneration will be better understood to control cancer and enhance the regrowth of organs. Why is it that some animals have the ability to regrow certain organs and why do some animals not get cancer? Why do some animals live long lives and some short lives? The questions are many. Darwinian Medicine may have the answers to these questions. The answers are already there, waiting to be discovered.