Biology’s Integrating Insights for Medical Science
This is an open letter to medical educators because my contact with the public has identified many individuals outside the field of medicine who were interested and benefited from these discussions. Evolutionary biology belongs in the curriculum of medical school—not as a separate course (perish the thought) but here and there to enhance the learning and interpretation of other material from biochemistry to psychiatry. Here are examples from biochemistry: acclimatization to high altitude and detoxification of foreign chemicals (natural or otherwise) and from psychiatry: drug addiction and homosexuality. I will flesh out these and other examples in the following autobiographical material to show how evolutionary biology has enhanced my education not only in medical school but also throughout my life as a perpetual student of medicine and life. I hope that these details of my personal “curriculum vitae” in evolutionary biology will help all students, even perpetual ones (the end product of an adequate education), long past formal schooling.
Adaptation to darkness and altitude. Why does it take 30 minutes to get thoroughly used to the dark? This happens to be the duration of tropical twilight. the fastest twilight worldwide. Prior to artificial lighting, adaptation in less than thirty minutes had no additional survival value. (Solar eclipses, which darken more quickly, are too rare to represent any appreciable selection pressure.) Why does it take several days to get used to high altitude? Acclimatization to high altitude takes about as long as it takes a mammal to get to high altitude on its own power. Birds, with their ability to reach high altitudes rapidly, have a more powerful adaptation, a countercurrent blood gas exchange system in their lungs.
Let me tell you how I became an evolutionary biologist at an early age. My academic credentials as a biologist are limited to freshman biology in college in 1940, a college course in comparative anatomy, and medical school. As the youngest of four children, I remember some family conversations which were probably over my head about the Scopes trial (see below); but I got the impression that my parents intellectually leaned toward acceptance of Darwin though they perhaps wished that it wasn't so. My biological epiphany came in my sophomore year in high school. A friend was telling me what an evil man Darwin was. I asked "Have you read any of his stuff?" "Of course not," she replied. So, naturally, I proceeded to read the Origin of Species (3). Quickly it became apparent that Darwin was not primarily out to make trouble: there was so much detail about pigeon breeding, mules, and such. I believe that I went straight to the source, Darwin, as a result of a childhood experience.
At age four or five I had learned that original sources intended for adults were the most interesting. My parents were quite supportive of my questioning. When I heard that there was more to Gulliver's Travels (24) than the Lilliputians and Brobdingnagians, I persuaded my mother to get the complete book from the library. After the midgets and the giants the next country that Gulliver visited was the land of the Houyhnhnms (my mother pronounced it whinneys) where the intelligent beings were horses. The creatures that looked like humans didn't know anything. The horses called them Yahoos. This kind of education is especially appropriate when a parent participates to explain and answer questions.
My thorough reading of Darwin made me an evolutionary biologist practically overnight. I began making surmises about the biological basis for characteristics of humans and other animals, both physical and behavioral. "Biological basis" refers to the survival value of an anatomical structure, ability, or behavior and its likelihood of undergoing natural selection and inheritance. In essence, I became an evolutionary biologist and a socio-biologist simultaneously. More on sociobiology later (page 6). Now let us look at several more examples of such surmises including some more complicated ones:
Why is lactose (milk sugar) scarcely sweet? If milk contained any other ordinary sugar, it would be almost as sweet as watermelon. Lactose is created in all milk glands at the expense of some sophisticated biochemical manipulations and also requires special enzymes for digestion in all mammalian young. This biochemical complexity would require some selective advantage in order to have occurred at all. My take: it would be harder to wean the young from sweet milk at the appropriate time resulting in fewer offspring per such mother during her reproductive life—a substantial selective advantage for mothers producing milk with lactose instead of a sweeter sugar. Perhaps sweeter milk of early mammalian progenitors without the lactose chemistry resulted in the entire lineage having a sweet tooth throughout life to the detriment of their nutrition. The evolution of the lactose biochemistry thus may have resulted in return to a more varied and nutritious diet with enhanced survival of all mammalian species. This kind of thinking may help future physicians steer our communities toward appropriate policies to cooperate with nature’s long-term effort to limit the damages of having a sweet tooth. Getting “pop” machines out of schools becomes a “no-brainer” with this kind of insight.
Whale communication. In his remarkable book, Among Whales, (21), Roger Payne describes how much money is spent by whaling countries to try to discover the breeding grounds of blue whales, so far without success. There is probably no breeding ground as such since the blue whale’s auditory and vocal equipment permits communication with each other across ocean basins, but no farther than the largest of these, the Pacific basin. Thus, the whales have no problem locating one another and do not need to be near each other to locate mating partners. Note that there was no biological selection for this kind of fitness beyond what the whales need.
Sickle cell anemia, a disease common in black people, is an example of how even seemingly deleterious characteristics can have survival value under special circumstances. Homozygotes, people who inherit the gene from both parents, die of the disease before reaching reproductive age. Heterozygotes, who have one gene from an unaffected parent, actually have a survival advantage, as they are resistant to malaria. In malarious regions of Africa, mathematicians tell us that the observed incidence of the abnormal gene is just enough to maximize the benefit to the population as a whole.
Homosexuality may be another instance where a trait seemingly disadvantageous to the individual's capacity to pass his genes on to offspring may enhance the survival of the population as a whole. You may well ask "How can evolution select for a trait which does not reproduce?" The homosexual example is even trickier than the example of sickle cell anemia. I puzzled about it for decades until stumbling on an article about comparative primatology which described homosexuality in a number of primate species. The thesis was that homosexuality motivated the non-dominant males to stay with the troop, strengthening the group and enhancing the survival of the individual's other relatives (siblings, nieces, and nephews) who will pass on that male's genetic attributes. I am sure that these extra males also help with tribal territorial warfare—a pre-human precedent for gays in the military if you will.* Homosexuality is the salient example in my personal experience of the power of evolutionary biology in learning and making interpretations. When the American Psychiatric Association decided a few years ago that homosexuality would no longer be an acceptable medical or psychiatric diagnosis, instead of being upset or even surprised, I promptly gave them credit for being ahead of the curve of new knowledge from Jane Goodall and her ilk.
Obesity. A somewhat modern insight into the biological background of obesity comes from study of the Pima Indians of southwest USA. The Pimas have the highest incidence of obesity of any ethnic group worldwide. They descended from ancient inhabitants of very arid canyons of the four corners area, such as Mesa Verde in Colorado and Grand Gulch in Utah. Their ancestors were survivors of drought and famine in endless sequence so they were preferentially selected for the ability to gain weight promptly when food again became plentiful, thus increasing their chance of survival in the next famine. We are all a little like that though to a lesser degree. If we understand how we got the way we are, there may be opportunities to adjust our behavior to blunt undesirable consequences--another example of the benefit of scientific literacy.
Megavitamins. Another surmise of special interest in light of current enthusiasm for mega doses of vitamins begins with the fact that we humans are a member of a very short list of animals who do not synthesize vitamin C in our bodies. We can still synthesize many other vital substances, such as lecithin, in any amount needed for health, but not Vitamin C. (Lecithin deficiency has never been observed.) When our early or pre-human ancestors started to lose the ability to create vitamin C, this was surely not an important handicap, or their ability to reproduce would have been affected. We must conclude that the foods available to our ancestors in their environment had ample amounts of vitamin C. Similarly, if other essential substances had been present in sub-optimal quantities, there would have been selective evolutionary pressure enhancing the ability to conserve these nutrients. Hence a varied diet is very likely to contain adequate amounts of all nutrients
*The article about primatology is without bibliographical reference because I read it on a plane where some other passenger had left the publication. I did not keep the magazine because I did not realize the article’s full significance immediately. I do recall that it was an alumni magazine of a major private university, dated in the early 1970s. In honor of this experience I have sought out other alumni magazines from such universities, occasionally sending a contribution and a request to be on the mailing list. Such magazines have been good sources for reliable and provocative material that might not survive editorial scrutiny and "self-censoring" in the advertiser-driven commercial media. There are other magazines that fall in this category, notably the Skeptical Inquirer, Free Inquiry, The Atlantic Monthly, Harpers, the Scientific American, and even The New Yorker.
assuming total calories are also sufficient. A corollary to all this is that hunter gatherers should be less subject to malnutrition than settled agriculturalists because of their ability to move on quickly in case of a local food shortage.
You may have detected some skepticism on my part about the need for vitamin supplements to maintain vigorous health. I have a dear friend whose wife occasionally chides me for not taking vitamins as supplements. One Friday evening, when I was tired and perhaps a little irritable, I responded to her somewhat testily, “Sure, Nancy, I believe in vitamins, if you have arthritis of the jaw.” Her reply taught me a great truth: If you say something slightly offensive to someone who wants to like you, they may misinterpret you. Nancy replied, “Oh, Doc, I am so glad you realize that vitamins are good for arthritis!” I quit the discussion while I was ahead, not even mentioning that I might actually be taking vitamins because I had volunteered for a study from Harvard University to test whether supplements of vitamins A, C, and E prolong life. Harvard supplies either dummy pills or vitamins to doctors who are not taking other supplements to get a clear separation between the test group and the control group. This is an ethical experiment because it is not known which group, if either, will have the greater longevity. However, we are aware of a few instances where evolution has lagged behind a need occasioned by new circumstances.
When our ancestors left the tropics, incident ultraviolet irradiation of our skin no longer sufficed for optimal vitamin D synthesis from its precursors in our black skin especially with colder climates requiring more and more clothing. Vitamin D precursors obtained from the diet or formed in the skin from sun exposure need to be activated by two chemical steps in the liver and kidneys—vitamin D intoxication occurs only from preformed vitamin D in artificial supplements (8). A second instance is gradually decreasing ability to absorb vitamin B12 from the diet in old age (scarcely solvable by survival of the fittest because the problem occurs long after reproductive age—waiting for improved survival of orphans because of healthier grandmothers would be a very long wait).. Strict vegetarian diets are severely deficient in vitamin B12. Many vegetarian animals solve this problem by eating their own feces (normal intestinal flora synthesize vitamin B12). These sorts of problems are more likely to be solved by our evolving intelligence than by direct evolution of biochemical processes.
Recognition – friend or foe. The instant recognition of faces is a “hard wired” ability that is of obvious survival value in terms of recognizing friend or foe. This ability has been well studied by students of animal behavior. I was especially intrigued by recent research on face recognition using sheep as the study subjects (13). Twenty sheep were trained to recognize pictures of sheep or human faces that were placed at junctions in a maze with food rewards for correct choices. The sheep were very adept. If sheep can do it, who can’t? The evolutionary implication is that humans and sheep must have had a common ancestor some tens of millions of years ago already in possession of this brain circuitry. Voice recognition, our next topic, is also part of recognition friend or foe and may be the underlying ability that enables us to appreciate music.
Music appreciation is almost impossible to explain, illustrated by this quotation from Charles Darwin himself in the Descent of Man:
“As neither the enjoyment nor the capacity of producing musical notes are faculties of the least use to man…they must be ranked amongst the most mysterious with which he is endowed.”
The sophisticated ability to analyze and appreciate music (even by non-musicians) defies direct rationalization by saying it has survival value for its own sake. Rather it must be riding “piggy-back” on some other biological imperative. What can this imperative be? In medical school physiology class, we did informal experiments to demonstrate our ability to localize the direction of origin of a sound. Apparently this ability is hard wired, not learned. We are born with it. Babies can do it from an early age. It depends on differential loudness in the two ears and even more on the different arrival time of the sound in the two ears. This phenomenon demonstrates that tiny differences in sound arriving in the two ears is noted by the brain and meaningful calculations are automatically made. However, this explanation is still a long way from identifying a biological basis for music appreciation. The following anecdote describes a possible breakthrough in thinking.
When we went through Peace Corps training in l968, our l4 year old daughter chose to take training for teaching English as a second language with the college graduate volunteers and was permitted to do so since the Peace Corps encourages flexibility. Ten years later, after no further contact with Norman, a fellow student, she answered the telephone in a Manhattan home where she was a houseguest. It was a wrong number; but she recognized Norman’s voice and replied to him instantly in Farsi, their mutual exotic language, and they both freaked out. I am sure we have all had similar if less striking episodes of sudden recognition of voices out of context with no helpful clues.
Gradually, I realized that this ability is automatic, that it is not learned, and that it has enormous survival value, comparable to the electronic equipment in military aviation that is programmed to recognize other aircraft as friend or foe. The minute details of the sound of the same words spoken by different vocal apparatus, which we perceive so readily, could be a correlate of "music" appreciation with selection for survival. Our varying response to different pieces of music is probably related. Familiar music is comforting so we feel pleased and reassured on hearing a tune we recognize and have long enjoyed, work songs lighten the burden of hard work, and marching music keeps the military marching on through difficult times. A further point confirming that music appreciation is related to the hard wired “identification of friend or foe” is the commonplace fact that songs are much easier to “memorize” than even rhythmical prose and that the tune is even easier to remember than the words. Learning tunes is almost inadvertent at times.
It is of interest that trained musicians are less likely to have absolute pitch than the rest of us, and primitive races of man still possess this trait (many things that we learn are more interesting in retrospect than when we first learned them—I am still looking for the reference). Bird songs, if not many others, are identifiable not only by the tune, but also by the pitch, which is absolute, thus helping primitive man to interpret the sounds of the jungle more promptly. Other animals may also have absolute pitch (16). Modern musicians are confronted with the transposing of many pieces to make them easier to sing for a particular group. Besides. the frequency of the “standard A” has been increased by some committee a couple of times in my lifetime. In summary, music appreciation requires much sophisticated neural circuitry that evolved to enhance identification of sounds especially voices, so music appreciation is riding rather incidentally (piggyback) on high priority survival traits. In other words, without the preexisting ability to gain so much information effortlessly from sound, music appreciation would not have happened. Compare with literature arising from language and literacy with no new biological evolution.
“All Substances are Poisons… there is none which is not a poison, the right dose differentiates a poison from a remedy.” – Paracelsus (1493-1541)
Paracelsus’ comment was rather advanced for the time; he was arguably the most eminent physician of the Middle Ages. We stand on the shoulders of giants. Chemical warfare between plants and animals has been ongoing for millions of years and has become very sophisticated, as I will describe. In medical school I found biochemistry quite fascinating. We learned about how sugars and starches created by plants are processed in the animal’s digestive tract, liver and muscle; but the photosynthetic process for carbohydrate production and creation of other chemicals by plants was a “black box”—details unknown. Since then I have learned some plant biochemistry that provides unexpected insights about human medicine and some incidental things that are just plain interesting. For instance, corn and a short list of other plants have an “overdrive” mechanism for getting about 15% more photosynthetic mileage out of a given amount of light compared to the rest of plant life. A cornfield in July is so efficient that, on a calm day, it exhausts the carbon dioxide from the air in the vicinity of its leaves. Thus it grows measurably faster in a slight breeze that brings in new air with its full 0.04% carbon dioxide.
Nearly one half of all plants spend a major part of their chemical energy derived from light in synthesizing alkaloids, complex chemicals like strychnine, atropine, digitalis, curare, caffeine, nicotine, quinine, morphine, cocaine (7). When I learned of the large percent of energy available to plants that goes into synthesizing these alkaloids, I reasoned that these chemicals must be of considerable utility to the plants that produce them. These poisons limit the eating of these plants by insects and animals. When I was a child, I remember nicotine, packaged and labeled as such in hardware stores for use as a garden insecticide. So, if these chemicals had not been useful, the cousins of plants that were without this drain on energy would have out-reproduced them, resulting in the extinction of those plants that wasted energy producing “useless” chemicals.
So far chemists have characterized 10,000 or so of these chemicals in various plants. Now for the animal contribution to these eons of chemical warfare: We and our fellow mammals share many similar chemical mechanisms for disposing of these chemicals, and these mechanisms are active also against a great variety of unnatural substances including synthetic drugs, insecticides and herbicides. The mechanisms include oxidation, reduction (the opposite of oxidation) and hydrolysis, splitting the chemical into two small ones that are then dealt with as if they had been taken in separately. Other enzymes synthesize new chemical entities by adding fragments of carbohydrate, amino acids, acetic acid, or even inorganic sulfate, rendering the original material more soluble and more readily excreted in urine or bile. When the possible effects of administering a new drug or chemical are studied, no general rules have been discovered to predict the outcome. Separate experiments to determine toxicity, biotransformation and excretion are required. Additional complications involve enzyme induction and changes in response depending on the simultaneous presence of other substances. In enzyme induction the activity of the enzyme transforming a substance may increase as much as fourfold after a few days exposure and persist for nearly a week after the new chemical is removed. A newly introduced chemical transformed by the same mechanism will have its transformation accelerated without further induction. If the first drug or chemical in the above series was the more powerful inducer, its removal might result in more toxicity of the second drug or chemical because of delay in destruction. For example, stopping phenobarbital or a similar sleeping pill in someone whose Coumadin (anticoagulant) dose had been adjusted properly might result in Coumadin toxicity from the previously appropriate dose.
The power of the liver is illustrated by the “first pass effect”. All the blood from the stomach and intestines passes through the liver before going back to the heart and everywhere else. The “first pass effect” means that some chemicals such as nicotine are virtually eliminated from the blood in its first pass through the liver so that none enters the general circulation. To get a fix, a nicotine addict must absorb the drug through the lungs, the lining of the mouth or through the skin with a specially designed nicotine patch. Inderal, also known as propranolol, is a synthetic chemical (it does not occur in nature) which is 98% destroyed in its first pass through the liver. This means that, for equal effect, an oral dose must be 50 times an injected dose because the injected dose bypasses the liver.
The liver stores toxic chemicals that have not yet or cannot be eliminated from the body. An intriguing example is enormous amounts of vitamin A stored in the livers of mature polar bears. There is so much stored vitamin A that a half pound portion of the liver contains a dose that would be fatal to humans. Eskimos do not eat polar bear liver. The polar bear itself is unaffected. Presumably the polar bears have adapted to some items of diet very high in vitamin A. How this happens is still a mystery. New information often raises new questions. Need I remind you that we have been discussing chemical warfare between plant and animals in a geological (and evolutionary) time frame?
Addiction. Tolerance is a mechanism permitting consumption of plants with toxic effects, and it causes drug addicts to be able to survive, even thrive, on otherwise fatal doses of the drug to which they are addicted. A corollary to this is the idea that addiction has persisted by being tied incidentally, but inextricably, to tolerance. Thus, seemingly harmful traits can survive natural selection if they are associated with a trait of great benefit to the species. Could drug addiction be such a harmful trait unavoidably connected with tolerance and could its survival value be in permitting greater consumption of a “dangerous” food? Could addiction be a vestige of an inheritance from some ancient, long extinct ancestor who actually benefited from the trait (most likely a fish)? There are modern insects whose larvae become “addicted” to toxic plants to render the entire species toxic to predators. An example is the common monarch butterfly which eats poisonous milkweed and thereby avoids predators. While this strategy of becoming tolerant to a poison was evolving, addiction may have become part of the package because that assured an adequate, steady intake of the poison—stragglers in becoming addicted became prey and ceased to be part of the lineage. Countless other such fascinating discoveries await us especially in the tropics, for example, butterflies of the genus Parides in Central America whose larvae eat Aristoloquia leaves—toxicity similar to milkweed. (28).
So the following scenario may partially explain the origin of addiction. Unlike the Parides larvae which hatched on a poisonous Aristolochia leaf, our aquatic ancestor (“most likely a fish”) which “invented” addiction would have to keep seeking the poisonous food that rendered its lineage poisonous and therefore less subject to predation. Addiction served this purpose by overcoming the temptation of ample alternative food choices. In our case, the ability to become addicted just happens to have persisted after its benefit became moot. Compare with our appendix persisting also with negative benefit. More toxic animals and plants inhabit the marine environment than our terrestrial one. Undoubtedly some of the toxic species utilize second hand toxins as the Parides larvae do—PhD thesis material awaiting elucidation along with how were/are the fish hatchlings induced to eat enough of the toxic food to become addicted. If we can find a poisonous marine vertebrate that achieves toxicity by diet, this will begin to confirm the hypothesis of an evolutionary origin of addiction especially if that species bears live young so that they would be born addicted as are human infants born to mothers who are currently addicted to heroin. Experiments with a captive population of such animals should easily demonstrate tolerance or even tachyphylaxis, the ability of former addicts to become re-addicted extraordinarily promptly. It is a universal feature of the addiction syndrome (along with tolerance and drug-seeking behavior).
My personal experience with caffeine addiction is a good explanation of tachyphylaxis —significant because it was so extreme but still not disabling or otherwise harmful except for occasional withdrawal headaches. When I lived Afghanistan from 1968 to 70, I had not previously been a regular user of caffeine, but, while there, I frequently drank tea in order to get boiled water without insulting the local water. Actually I dislike tea and frequently easily weaned myself from it in about a week unless I was expecting to travel. It takes much tea to fill one’s water requirement in a tropical environment, so my addiction frequently exceeded toxic doses. Tachyphylaxis restored my addiction sufficiently promptly to avoid any toxic symptoms, emphasizing to me how tachyphlaxis got into the addiction package along with a withdrawal syndrome and tolerance..
My unusual personal insights into tachyphylaxis came in the next decade or so of almost total personal avoidance of caffeine. The amazing discovery was that on the day after a few midday coffees, I would get a headache 4-5 hours after the first “missed dose”. I have had no experience with patients having such headaches if they drank less than 5-6 cups per day. Now I drink no more than a cup or two of real coffee a month.
What little is already known about the biochemistry of addiction is merely a discussion of the possible interactions of neurotransmitters with the mesolimbic dopamine system where pleasure is produced and how some of the addicting substances produced by plants are similar to, and imitate, various neurotransmitters (1, 17,19,25). The literature seems to contain very little about how addiction could enhance survival (20).
The bottom line: regard addiction as like having an appendix and don’t bother with the cure until threatened by some inconvenience.
Herbs. The 10,000 or more natural chemicals produced by plants are all capable of interacting in presently imponderable ways with each other and with purified herbs dispensed as drugs, e.g. digitalis, quinine and synthetic chemicals from the environment or dispensed as drugs. Let us give the public practical advice which flows from this: “Get all of your medications from one pharmacy, even prescription eye drops because they go through the nasolacrimal duct and are swallowed. Modern pharmacies put your entire list of medications on a computer that is programmed to look for drug interactions like those we have been discussing. The pharmacist who discovers a potential adverse interaction will call your doctor. If the pharmacist asks you about herbal remedies, list those also, although the vast majority of interactions among herbs and interactions of herbs with medications are presently unknown and will remain so considering the enormous numbers of combinations that would have to be tested in animals or volunteers, one combination at a time. The bottom line: Take herbal remedies for minor illnesses if you choose to ignore their occasional toxicity and adulteration. But if you have a serious acute illness or a chronic one, stop your herbs until you talk to your doctor.” Why doesn’t the FDA (Food & Drug Administration) take charge of these problems? Because Congress removed “food additives” and herbal remedies from the FDA’s jurisdiction in the early 1990s except for deaths and life threatening events.
Sociobiology. This term was coined by Harvard University professor, E.O.Wilson (27), a world authority on social insects. His book, Sociobiology, published in 1975, explored biological contributions to culture, both animal and human, and led to great controversy for more than a decade. It was one thing to compare man to animals anatomically and biochemically; but many of Wilson’s peers considered human culture beyond such comparison. Wilson was persecuted--some students even poured ice water over him just before he started speaking at a session of the AAAS (American Association for the Advancement of Science) (23). The problem was that these persecutors thought Wilson was trying to justify racism and anti-feminism by implying that such things could be preordained by inheritance. Ironically, Wilson's politics were actually quite liberal.
During my lifetime there have been a series of efforts to define man's uniqueness. First, man was considered to be the only tool-using animal; but chimpanzee observation put an end to that distinction. Even sea otters use rocks for anvils and hammers to break shells. Culture turns out to be less specific to humanity than was thought before detailed studies of animal behavior were completed. We have already mentioned homosexuality in primates. Herbal "remedies" used by animals are another example of animal culture influencing animal behavior. In the following example a pregnant elephant was teaching her daughters what to do about delayed onset of labor: Holly Dublin (9), the Jane Goodall for elephants, spent decades observing what elephants do every day as well as some of their more rare activities. One day in 1980 a very pregnant elephant took off at a fast pace with two of her daughters. Holly had known the daughters since their births. The elephants traveled far out of their home territory and stopped at a small, unusual tree where the mother ate most of the leaves of the tree before heading for home. The next day the mother gave birth. Holly had saved a few of the remaining leaves of the tree for identification. When Holly asked the ladies of a nearby village about the leaves, they laughed and laughed. It turned out that the local women also used this herb to induce labor.
When chimpanzees are sick they have been observed to eat the leaves and bitter pith of some plants which they do not normally eat. Analyses of these plants show that about half of these plants contain alkaloids, drug-like substances, some of which are active against intestinal parasitic worms. One of these leaves (which the chimpanzees swallow whole) has velcro-like hairs which entangle a species of small intestinal worm and cause them to be expelled in large numbers, something that wouldn't happen otherwise (10). While I was writing this, it occurred to me that animals even have recreational drugs discovered by animals for animals. Years ago a farmer told me about his bull who was in a pen near an old fashioned silo that leaked. The bull pawed the ground to make a lake of the silo fluid and proceeded to drink the resultant liquid which made him tipsy. Cat lovers realize that cats discovered catnip on their own. Horses like locoweed and seek it for the high. This is the origin of the slang expression "going loco" being used to describe some psychotic behaviors. I cannot prove such uses of “recreational drugs” depend on animal culture; but it is an interesting aside.
Cultural features common to humans, chimpanzees, bonobos, and gorillas date from a common ancestor. Scarcity of resources leads to sharing in all four of these species. Moral outrage and sanctions for correction are usually carried out by dominant individuals; but coalitions of subordinates may limit abuses by dominants. Suppressing bullies may have been a precursor of morality (2).
Tool use and culture are not the defining distinctions to separate man from other primates. Language appears to be a much better candidate. Although bonobos, chimps, and gorillas can be taught a few meaningful verbal responses, advanced symbolic thinking depends on language to a degree that is beyond them. Modern man is perhaps 30,000 years old genetically, meaning there has been little selection of new genes since that time. Our recent rapid progress depends on transmitted culture, not new genes. The concerns of the eugenics movement about possible genetic deterioration in our species have turned out to be more of an interesting idea than true. The concerns of the opponents of sociobiology are similarly erroneous in the other direction. We cannot take care of our future by hoping that our biology does not influence us. We must accept our instincts as given and proceed to rise above them when appropriate. It is too late for natural selection to improve us. Sociobiology is now helping to lead these efforts in the person of ethologists (students of animal behavior), cultural anthropologists, and even a veterinarian or physician here and there. I suggest reading Ever Since Adam and Eve, a truly remarkable book (22) written by an obstetrician and a veterinarian who specializes in animal reproduction.
Teaching evolution. Physicians and veterinarians, as a result of their status in their communities and their training, are well suited to counter the kind of thinking which caused the Kansas State Board of Education in l998 to outlaw exam questions about evolution in their public schools. More recently the Dover, Pennsylvania School Board attempted to mandate teaching “intelligent design” as part of the high school biology curriculum. In the l920's, legislation in Tennessee completely prohibited the teaching of evolution. John Thomas Scopes was a young biology teacher who challenged the law by including the study of evolution in his courses. In a spectacular trial in l925, William Jennings Bryan, a recurrent candidate for president of the United States, assisted the prosecution and Clarence Darrow, a nationally known criminal defense lawyer, assisted the defense. The prosecution "won" and Scopes was fined $100. These events were colorfully recorded in both The Monkey Trial by H.L. Mencken (18) and a more modern play Inherit the Wind by Jerome Lawrence 15). A reluctance to teach modern biology in U.S. public schools persists even today. Teaching biology without teaching the origin of species is like trying to teach physics without the theory of gravity. DNA (deoxyribonucleic acid) is the stuff of inheritance for all life on our planet--the actual material of genes. The DNA of chimpanzees is 98% identical to that of humans. Even insects have enzymes in common with us, coded by the same DNA sequences and preserved through time since a common ancestor actually reproduced these genes millions of years ago. All of this additional detail was amassed years after Darwin. He believed in the inheritance of acquired characteristics, a prevalent error before Gregor Mendel discovered modern genetics in 1865. A copy of Mendel’s report in an obscure journal was found in Darwin’s unread mail after his death.
Creationism and Intelligent Design are continued attempts to insert religion into the science curriculum. Intelligent Design tries to do this but falls of its own weight for the following reason, among others. Evolution can only build on structures and biochemistry which already exist. When an innovation has great benefit, there may be undesirable consequences persisting until further selection sorts things out. Two such traits persisting in humans are a jaw too small for its intended teeth and a birth canal too small for the large head of human infants producing an unacceptable maternal mortality under primitive conditions. The point is that no “intelligent” design would permit such defects in the first place. With the development of modern dentistry and obstetrics these two defects may never be selected out. Was temporarily increased maternal mortality too high a price for our species to achieve superior intelligence (remember the large infant brains and heads)? Compare with sickle cell disease and its countervailing resistance to malaria. Chalk one up for the intelligent head and new, still natural, methods of sorting things out like pulling wisdom teeth and Caesarian sections in this instance. Remember also the modern need for vitamins D and B12 supplementation that we have already discussed.
The power of evolutionary thinking is further illustrated by Wallace's line (5). Alfred Wallace (1823-1913) was a naturalist who studied and collected data in the Amazon and later in Indonesia. He independently discovered organic evolution at about the same time as Charles Darwin. To the credit of both, they never had a priority dispute. Wallace surmised on the basis of biological evidence alone that continents had moved great distances, anticipating plate tectonics by more than a century. Wallace's line passes between Borneo and the Celebes (now called Sulawesi). Except for some birds, the flora and fauna on the two sides of this line are so different that Wallace proposed that the narrow strait between them was, in geologic time, formerly an ocean separating the continental shelves of Australia and Asia. In the last few decades geologists rediscovered the same thing (of course, using their modern methods). This is an especially fascinating episode in the history of science. This leads us to memes.
The Evolution of “Memes.” Hope for the future must be in the realm of ideas. Ideas have a life of their own, propagating and evolving much faster than genes. Some are harmful, like female genital mutilation, and deserve to die out. Others have been useful in past millennia, but may have persisted beyond their usefulness. To emphasize the importance of such ideas, Richard Dawkins has called them "memes" (4). Cultural anthropologists tell us that all cultures have myths to explain origin and purpose (14). In tribal groups these myths enhance cooperation and governance and improve survival chances. These beliefs often enhance distrust of foreigners and even promote "ethnic cleansing". A few hundred years ago a new meme arose which held that myths should no longer govern our public decisions. It has made considerable headway. For instance, slavery can no longer be condoned on the basis of the myth of racial inferiority. Biology helped to launch this successful meme in the person of Alfred Wallace, the previously mentioned naturalist. He was the first prominent citizen anywhere to state publicly that primitive races were not inferior in intellect or moral fiber, nor inferior in any other respect. He knew this from his years of traveling alone with those primitive races and trusting them for his survival. This meme is beginning to stick. The last government sponsored slavery in the world ceased in l886, in Brazil.
Abuse of the environment. On the other hand, we tend to over-idealize primitive societies. Hunter-gatherers were replaced by settled agriculturalists because of population pressure. Slash and burn farmers return to hunting and gathering when able to choose because it is less labor intensive (11). Mankind has always over-exploited the environment until recently when new memes about protecting our resources have risen and been accepted. Primitive man just didn’t have chainsaws. I am amused when told that capitalism is the natural economic state of man. It is obvious that accumulation of wealth was not an option for hunter gatherers. When some of them bagged a woolly mammoth, what better option did they have than to declare a socialistic feast and hope their neighbors would reciprocate? There was no way to save the meat for future use. Socialism and communism were not thoroughly differentiated until Stalinism. Kerala in southwest India (12,26) illustrates a benign variant of communism. A communist government in power there for several generations after World War II promoted health and education (particularly for women) which resulted in manifestations of prosperity, even though their economic base was still one of the lowest of India's provinces. Education of women helped lower the birthrate in Kerala as it has done consistently throughout the world.. The outward appearance of prosperity is so convincing there that I have had to give documentation to friends from Kerala to make the point that Kerala is not economically prosperous compared to India’s other provinces. Kerala does still have a dearth of natural resources.
Population. When Jonathan Swift sent Gulliver to the land of the Houyhnhnms, Swift demonstrated that he was ahead of his time about overpopulation(24). The intelligent horses controlled their numbers by a rather rigid social protocol which wouldn't work for us. Bonobos, chimpanzees, and humans all utilize sex for social cement beyond its reproductive function(11,22). At the AAAS meeting in February, 2000, a Jesuit ethicist (6) discussed our obligation to exercise stewardship in maintaining our planet and the fact that overpopulation was in conflict with this goal. He went on to say that the Catholic hierarchy was about to consider some adjustments in the doctrine of original sin to further this end. I was reminded of a conversation with the Dean of the Missouri Bible College in 1955 in which he stated that he had it on good authority that the College of Cardinals had recently had a split vote about contraception. So some of the needed reforms may come from the top down, which will be a great relief for activists. So, bring on the journalists and other leaders to promote the good memes!
One final point about evolutionary biology in the classic sense: I recently heard a program about the superior performance of children sired by artificial insemination from Nobel Prize winners. Here are several problems I see with these reports:
· The journalists were probably reporting their expectations and prejudices.
· It is really the opposite side of the eugenics coin; genius, to the extent it is genetic, is a fortunate combination of genes found in the general population just as genetic intellectual handicap is an unfortunate combination of the same.
· Also, if the rich could genetically engineer for superior offspring by inserting new "designer genes", this might result in a gifted class with a natural divergence of interests--perhaps even a new species.
· Modern man and Neanderthals coexisted for only a limited time. We must guard against creating a new, academically based motive for ethnic cleansing.
· The pleas against modifying the human germ line had best be heeded until it can be accomplished in a way that "raises all boats".
A final word about memes. At least since Greek and Roman times we have entered a paradigm shift in the evolution of man by memes (ideas that propagate and influence events). This shift has come in fits and starts. In classic times a prominent motive for achieving wealth was to have leisure to study the wisdom of the ancients in libraries. During the dark ages, learning was preserved by monasteries and Islamic Universities. After the enlightenment the educated public also became concerned with preserving learning. Let us get on with the sifting and winnowing of the memes. We have wasted a century through limiting the scope of teaching modern biology in the United States.
Summary. When I started to write the above article several years ago my goal was to defend the teaching of modern biology and to demonstrate the power of evolutionary thinking in understanding and explaining many important and interesting phenomena. Since then, I have gradually received a crescendo of insight to suggest that evolution is a pillar contributing to mankind’s intellectual and cultural history. We can hope that further study will result in still deeper insights regarding the connections between evolution and social and political spheres. It took 400 years for Newton’s ideas to lead to space travel. We will need to digest Darwin more quickly if we are to achieve the hoped for benefits in time to avoid disasters like climate change and overpopulation. In short, the proper and widespread study of evolution is a vital and integral part of a liberal education. What field is better positioned to lead the way in this endeavor than medicine? Let us do it for ourselves and for the world. I am reminded of reading in my youth a book about the western frontier. The author stated that the frontier doctor was more likely than any other citizen to be forgiven for believing in evolution. I sense that this may still be somewhat true in which case we are “ex officio” leaders in the effort to teach biology.
John A. Frantz, MD, NASW, July 28, 2008
812 22nd Avenue,
Monroe WI, 53566-1672 email@example.com www.frantzmd.info
Here is a quote from Charles Darwin to his friend, Joseph Hooker about the brutal inefficiency of natural selection: “What a book a devil’s chaplain might write on the clumsy, wasteful, blundering, low and horribly cruel works of nature!”—(Charles Darwin’s opinion about Intelligent Design? I think so. JAF).
Johannes Kepler said it very well although in a different context. “Perhaps there is someone whose faith is too weak to believe Copernicus without offending his piety. Let him stay at home and mind his own business. Let him assure himself that he is serving God no less than the astronomers to whom God has granted the privilege of seeing more clearly with the eyes of the mind.” Astronomia nova,1609
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Supernatural explanations are off limits in science. Quantum mechanics is borderline, so we simply call it counterintuitive. Even string theory passes for science probably because nobody has tried to impose it upon us. A seminar on string theory was actually promulgated as Postmodern Physics.