A New Prescription:
The Evolution of Darwinian Medicine
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Traditionally researchers have looked for the immediate causes of disease as bacteria, viruses, parasites and more recently, genes.(1) Some scientists are now utilizing insights from evolutionary science to understand the process of disease and the human body's response to it.(2)
The new prescription to add a spoonful of evolutionary theory into time-honoured medical traditions, is part of a new wave of thinking called Darwinian Medicine.(3) A term coined(4) by George C. Williams, Ph.D., an evolutionary biologist at the State University of New York and Dr Randolph M. Nesse M.D., a psychiatrist at the University of Michigan Medical School,(5) it describes a field that is presently purely theoretical,(6) but fuelling much debate.
While it is agreed that natural selection does not shape disease itself, proponents of Darwinian medicine argue that since it does shape vulnerability to disease, an evolutionary explanation for this susceptibility(7) could alter the orientation of medical science. Darwinian biologists are addressing the issue of why sickness occurs, how the mechanism evolved and why natural selection has not discarded the genes that contribute to many modern ailments.(8) They propose that since promoting human welfare is subordinate to the objective of maximising genes' reproductive potential,(9) genes providing benefits and defences during the prime reproductive years, are passed on, although they may promote disease later in life.(10) Another possible cause of modern maladies according to evolutionary biologists, is the idea that present environmental conditions are unsuitable for the adaptive traits that some genes encode for, and may even exert a detrimental influence under certain conditions.(11)
Proponents of Darwinian medicine believe that evolutionary reasons for vulnerability to disease can be reduced to several underlying factors.(12) The observation that pathogens evolve more readily than the organisms they invade, has been touted as the reason infections continue to plague humanity despite modern medicine's advances.(13) Degenerative diseases have been explained by an environment vastly different from the one in which organisms evolved in.(14) Although it is widely agreed that genetic diseases may result from defective DNA,(15) Darwinian scientists propose that many of the genes that cause disease have benefits superseding their detrimental effects. This explains the persistence of some genes, even those promoting eventual metabolic deceleration and aging.(16)
Nesse and Williams argue that today's physicians are trained in thinking too narrowly about disease when learning to concentrate on an illness' immediate cause and are rarely encouraged to question why a disorder actually occurred.(17) A small but growing number of physicians are beginning to question the wisdom of treating unpleasant symptoms of illness, arguing that the body's "evolved wisdom,"(18) may be a more trustworthy guide than the latest medical texts.(19)
Since the evolutionary approach to medicine contends that design compromises account for much disease,(20) its proponents argue that not only symptoms, but a host of human frailties may be better understood, and someday treated through this understanding of health and disease.(21) Presently, medicine is dedicated to treating symptoms as well as disease. Fever and diarrhea are commonly seen as signs of ill health in need of palliatives. Profuse nasal discharge is a nuisance that should be suppressed until the cold or allergy has passed. A low iron count is a deficiency that requires correction. The medical community regards unpleasant physical reactions to disease, and other bodily disruptions, as harmful. The opposing view, promulgated by dissenting Darwinian researchers, advocates considering significance of symptoms before deciding how, or whether to treat them. They warn that suppressive treatment of uncomfortable reactions may delay recovery, since they override the body's natural defence system.(22)
Darwinian researchers have found that a moderate rise in body temperature during an infection is not just a symptom of disease, but an evolutionary adaptation used by the body to combat infection, by making the terrain inhospitable to invading pathogens.(23) Preliminary studies have shown that lowering a fever prolongs the course of the infection.(24) Researchers are hesitant to recommend forgoing aspirin and temperature reducing agents, since traditional physicians have expressed concern that the public may misinterpret this information and allow high fevers to incur damage, particularly in children. Nesse advocates further research and is "astounded"(25) that it has not already been undertaken.
One instance of evolutionary wisdom colliding with the well-intentioned ministering of modern medicine is the attempt to bolster the health of Somali nomads by administering supplemental iron to them for their anaemic blood, a result of highly restrictive diets. Western scientists were disturbed to find the incidence of malaria and other infectious diseases in the tribe escalated markedly. The original low iron levels apparently retarded infectious invaders. Correction of the 'deficiency,' removed a factor that had evolved to protect these indigenous people from a pathogen in their environment,(26) causing latent infections to resurface.(27) Advocates of Darwinian medicine are wary of correcting low iron counts accompanying ongoing infection. Their caution stems from the discovery that microbes require iron to multiply and a temporary reduction in the body's iron stores can serve as a defence against rampaging invaders.(28)
Modern medicine regards a pregnant woman's inability to hold down food just when her fetus requires optimum nutrition for development, as illogical and therefore pathological. Proponents of Darwinian medicine point out that evolutionary effects are not tailored for human comfort or optimal design.(29) Like any forward thinking doctor, the body's evolved medical team practises preventive medicine. The nausea, queasiness and other symptoms of morning sickness that often occur early in pregnancy may have foundations as a prophylactic against harming the newly conceived fetus. Bitter, pungent and other strong flavoured foods such as garlic, onions and coffee, contain naturally occurring toxins that the plants use to repel insects and pests. While most of these toxins pose no threat to healthy adults, the embryo may be particularly sensitive to these agents during the development of its major organ systems, two to eight weeks after conception. Since these toxins have the potential to interfere with the precarious development of the fetus, the morning sickness response may have evolved over time to diminish appetites for such foods. Women who do not experience morning sickness are two to three times more likely to miscarry than women who are afflicted with early pregnancy nausea.(30) Mainstream physicians point out that many women do not encounter morning sickness while for others the affliction persists longer than eight weeks.(31) They believe that morning sickness is more likely to be a response to the hormonal changes of pregnancy, than food toxins. Darwinian medicine advocates see these views as compatible with the evolutionary model, suggesting that increased sensitivity to the cues that indicate natural toxicity such as pungent odours and bitter tastes could be mediated by hormones and vary between individuals.(32) The "as yet unproved theory"(33) argues against use of anti nausea medication since suppression of the symptoms may inadvertently encourage detrimental dietary choices.
Modern medical theorists have questioned the evolutionary persistence of the vestigial human appendix. With a sole understood purpose of causing appendicitis and providing young surgeons with their first abdominal surgery experience, speculation has arisen concerning the structure's persistence. Darwinian medical theorists point out that a smaller, narrower appendix may be more prone to causing appendicitis because any slight inflammation will more easily obstruct blood supply, leading to infection of dead tissue. Since appendicitis was usually fatal before the advent of aseptic surgical techniques, individuals with genes for such an appendix would often have died before passing on those genes, while those with genes for a larger appendix would not have encountered these problems. Therefore this vestigial structure appears to have reached a size below which it cannot regress further for genetic and evolutionary reasons.(34)
Darwinian medicine not only helps explain reasons one should reconsider treating some symptoms of disease, it also suggests that many maladies that afflict humans are caused by a clash between the body's Stone Age physiology and the modern world.(35) Nesse and Williams argue that a better understanding of disease can be achieved if the human body is approached with the consideration that it is the result of millions of years of evolution. They try to understand its physiology in light of the environment in which it probably evolved.(36) The modern world has been likened to an unplanned experiment on a physiology that is better suited to life on the savanna than the urban environment of today.(37)
Darwinian physicians believe that efforts to control virtually all diseases could benefit from a more thorough application of evolutionary principles.(38) The union of health science with evolutionary biology offers an entirely new dimension to humanity's relationship with disease, as the possibility of determining the future course of many diseases becomes a reality. Findings from the field of evolutionary biology are yielding dramatic insights for health scientists, especially those involved in combatting infectious diseases.(39) The focus of Darwinian medicine is not only which symptoms to treat or ignore but a way of understanding microbes, which because of their rapid evolution will always be a step ahead of humanity unless their evolutionary power is understood and harnessed.(40) The rise of antibiotic resistant micro-organisms is an instance in which Darwinian medicine has the potential to come into its own. The premises on which its proponents operate, make this field the perfect candidate for devising a solution to this previously insurmountable problem.
With the technology of genetic manipulations a reality, and the growing temptation to eradicate genes causing aging and illness, the study of evolutionary medicine is pertinent.(41) Much of what medicine regards as disease or breakdown is actually a defence the body has evolved to protect itself from the possibility of more threatening ailments.(42) Nesse emphasizes that evolution is an incremental process.(43) Many of the body's apparent design flaws are not simply mistakes, but compromises. To understand disease more thoroughly, the hidden benefits of apparent mistakes in design need to be appreciated.(44) In approaching genetic manipulations, if the entire function of the gene in question is known, then an educated decision regarding its fate can be made. However, evolutionary science expects that each gene may have benefits as well as costs, many of which may be unrelated,(45) and advocates caution. In an age of biological breakthroughs, the evolutionary approach may inject some prudence into a field where answers to philosophical and moral questions are struggling to keep abreast of the developments.
Yet this fledgling scientific field is struggling for recognition.(46) Darwinian medicine is still long on theory and short on prescriptions, but it does raise the questions of whether attempts to alleviate symptoms cause more harm than good.(47) Although studies needed to offer definitive answers have yet to be performed,(48) chief proponents of the field are unconcerned by the mediocre reception of their ideas by doctors. They point out that challenging ideas are seldom met with instant approval - as Darwin himself could attest.(49) Putting together a new scientific discipline and gaining recognition is in itself an evolutionary process.(50) At this stage, Nesse and Williams are mostly focused on how questions should be posed rather than providing complete answers.(51) Another factor contributing to Darwinian ideas being overlooked in modern medical circles is that traditional medical research aims to discover differences between individuals to explain why one becomes sick while another remains healthy. Darwinian medicine attempts to understand why all humans are vulnerable to each disease.(52) Every trait requires an evolutionary as well as a proximate explanation. Disease, seeming to result from the weakness of natural selection rather than its strengths, would seem to be excluded.(53) This belief impedes many physicians from grasping the relevance of evolutionary ideas to their clinic and has prevented a Darwinian revolution in medicine.(54) Most critics do not deny the field's legitimacy, but point mostly to its lack of definitive answers and deficiency of clear guidelines.(55) Other opponents have misinterpreted Williams and Nesse's theories as advocation of the usefulness of disease, and the recommendation that nature be allowed to take her course.(56)
The Darwinian revolution of health care may be met with as much resistance as Darwin's own ideas in his time, since it too challenges some of humanity's conceptions of itself. Darwinian medicine is a reminder that the organs and systems that comprise the human body do not result from the pursuit of perfection, but millions of years of evolutionary compromises, designed to reap the greatest reproductive benefit at the lowest cost.(57) Although these realizations may threaten humanity's conception of itself as the pinnacle of natural selection's genius, researchers in the field reveal being awestruck at the wisdom and complexity of human physiology. They recommend the study of these ideas as an antidote to reports of rising apathy and disenchantment among medical graduates and practitioners. Darwinian physicians eagerly anticipate the amalgamation of these new ideas into modern medical practise, seeing them as empowering tools both for themselves and their patients.
 
 

 

Endnotes:
 

1. Su, K., no title, pg 1

2. Low, J., Dr., "Why We Get Sick?" Book Review, pg 2

3. Allman, W. F., Second opinion - never mind the pharmacy: the new wave of Darwinian Medicine, pg 19

4. Allman, W. F., Second opinion - never mind the pharmacy: the new wave of Darwinian Medicine, pg 19

5. McAuliffe, K., Outer limits; doctoring a la Darwin, pg 156

6. Allman, W. F., Second opinion - never mind the pharmacy: the new wave of Darwinian Medicine, pg 19

7. Nesse, M.D., R., Sickness can be good for you

8. Su, K., no title, pg 1

9. Wray, H., Why do we get sick? Ask your ancestors; evolution could explain some modern diseases, pg 55

10. Su, K., no title, pg 1

11. Wray, H., Why do we get sick? Ask your ancestors; evolution could explain some modern diseases, pg 55

12. Nesse, M.D., R., Sickness can be good for you

13. Nesse, M.D., R., Sickness can be good for you

14. Nesse, M.D., R., Sickness can be good for you

15. deoxyribonucleic acid

16. Nesse, M.D., R., Sickness can be good for you

17. Wray, H., Why do we get sick? Ask your ancestors; evolution could explain some modern diseases, pg 55

18. Wray, H., Why do we get sick? Ask your ancestors; evolution could explain some modern diseases, pg 55

19. Wray, H., Why do we get sick? Ask your ancestors; evolution could explain some modern diseases, pg 55

20. Nesse, M.D., R., What is Darwinian Medicine? A brief overview of Why We Get Sick: The New Science of Darwinian Medicine, pg 2

21. Wray, H., Why do we get sick? Ask your ancestors; evolution could explain some modern diseases, pg 55

22. McAuliffe, K., Outer limits; doctoring a la Darwin, pg 156

23. Kluger, Ph.D., M., a physiologist at the University of Michigan Medical School, Ann Arbor, in McAuliffe, K., Outer limits; doctoring a la Darwin, pg 57

24. Oliwenstein, L., Dr. Darwin, pg 2

25. Oliwenstein, L., Dr. Darwin, pg 2

26. Allman, W. F., Second opinion - never mind the pharmacy: the new wave of Darwinian Medicine, pg 19

27. McAuliffe, K., Outer limits; doctoring a la Darwin, pg 157

28. McAuliffe, K., Outer limits; doctoring a la Darwin, pg 157

29. Wray, H., Why do we get sick? Ask your ancestors; evolution could explain some modern diseases, pg 55

30. Allman, W. F., Second opinion - never mind the pharmacy: the new wave of Darwinian Medicine, pg 19

31. McAuliffe, K., Outer limits; doctoring a la Darwin, pg 157

32. McAuliffe, K., Outer limits; doctoring a la Darwin, pg 158

33. McAuliffe, K., Outer limits; doctoring a la Darwin, pg 158

34. Low, J., Dr., "Why We Get Sick?" Book Review, pg 2

35. Allman, W. F., Second opinion - never mind the pharmacy: the new wave of Darwinian Medicine, pg 20

36. Low, J., Dr., "Why We Get Sick?" Book Review, pg 2

37. Allman, W. F., Second opinion - never mind the pharmacy: the new wave of Darwinian Medicine, pg 21

38. Ewald, P. W., Evolution of Infectious Diseases, pg 1

39. Ewald, P. W., Evolution of Infectious Diseases, pg 1

40. Oliwenstein, L., Dr. Darwin, pg 3

41. Oliwenstein, L., Dr. Darwin, pg 3

42. Nesse, M.D., R., Sickness can be good for you

43. Nesse, M.D., R., What is Darwinian Medicine? A brief overview of Why We Get Sick: The New Science of Darwinian Medicine, pg 3

44. Nesse, M.D., R., What is Darwinian Medicine? A brief overview of Why We Get Sick: The New Science of Darwinian Medicine, pg 3

45. Oliwenstein, L., Dr. Darwin, pg 3

46. McAuliffe, K., Outer limits; doctoring a la Darwin, pg 158

47. Allman, W. F., Second opinion - never mind the pharmacy: the new wave of Darwinian Medicine, pg 21

48. Nesse, M.D., R., Sickness can be good for you

49. McAuliffe, K., Outer limits; doctoring a la Darwin, pg 159

50. Oliwenstein, L., Dr. Darwin, pg 7

51. Low, J., Dr., "Why We Get Sick?" Book Review, pg 2

52. Nesse, M.D., R., What is Darwinian Medicine? A brief overview of Why We Get Sick: The New Science of Darwinian Medicine, pg 2

53. Nesse, M.D., R., What is Darwinian Medicine? A brief overview of Why We Get Sick: The New Science of Darwinian Medicine, pg 2

54. Nesse, M.D., R., What is Darwinian Medicine? A brief overview of Why We Get Sick: The New Science of Darwinian Medicine, pg 2 and Nesse, M.D., R., Sickness can be good for you

55. Oliwenstein, L., Dr. Darwin, pg 8

56. Nesse, M.D., R., What is Darwinian Medicine? A brief overview of Why We Get Sick: The New Science of Darwinian Medicine, pg 2

57. Oliwenstein, L., Dr. Darwin, pg 5
 
 
 
 

Bibliography:
 

Allman, W. F., Second opinion - never mind the pharmacy: the new wave of Darwinian Medicine, Forbes, Forbes Inc., vol. 156, pg 19, 1995.

Davies, P., The Arts Have Lost It, The Australian Magazine, October 19-20, Sydney, 1996.

Dawkins, R., The Selfish Gene (2nd Edition), Oxford University Press, Oxford, 1989.

Ewald, P. W., Evolution of Infectious Diseases, preview of a forthcoming book, Life Sciences, November 1996 (tentative).

Kingsland, Ph.D., M.D., S., Why We Get Sick: The new science of Darwinian Medicine, Book Review, World Wide Web, NEJM Homepage, Massachusetts Medical Society, 1996.

Lewin, R., Ecology of modern humans, Science, vol. 237, pg 1295, 1987.

Low, J., Dr., "Why We Get Sick?" Book Review, World Wide Web, CyberMall, CyberMall Pte Ltd., 1995.

McAuliffe, K., Outer limits; doctoring a la Darwin, Good Housekeeping, Hearst Corporation, vol. 215, pg 156, 1992.

Miele, F., Darwin's Dangerous Disciple: An Interview With Richard Dawkins, World Wide Web, Skeptic, Skeptics Society, California, 1995.

Nesse, M.D., R., Sickness can be good for you, The Times, 9 June 1995.

Nesse, M.D., R., What is Darwinian Medicine? A brief overview of Why We Get Sick: The New Science of Darwinian Medicine, World Wide Web, University of Michigan, Ann Arbor, 1996.

Nesse, M.D., R. M., and Williams, Ph.D., G. C., Why We Get Sick: The New Science of Darwinian Medicine, Vintage Books, New York, 1994.

Oliwenstein, L., Dr. Darwin, World Wide Web, Discover, 1995.

Rogers, M.D., S. A., You Are What You Ate, A Macrobiotic Way: An For The Resistant Diseases Of The 21st Century, Prestige Publishing, Syracuse, 1988.

Su, K., no title, World Wide Web, Discovery, Discovery Communications, Inc., 1995.

Wray, H., Why do we get sick? Ask your ancestors; evolution could explain some modern diseases, U.S. News and World Report, vol.119, pg 54, 1995.

Wright, R., The evolution of despair, Time, vol. 146, pg 50, 1995.



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