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Home , Evolutionary medicine

Education Evolutionary in the Curriculum

RANDOLPH M. NESSE AND JOSHUA D. SCHIFFMAN

The principles of are finding new applications in ,but little is known about the role of in medical curric- ula. To determine which aspects of evolutionary biology are included in medical curricula and the factors that influence this, a questionnaire was sent to all deans at North American medical schools who are responsible for curricula.The questionnaire asked about content areas in the curricu- lum,their perceived importance, and the factors that influence the amount of coverage given to those areas. Forty-eight percent of the deans who responded considered evolutionary biology important knowledge for . Only 32 percent of the respondents reported that their schools covered at least 8 of 16 core topics in evolutionary biology,and only 16 percent of the schools reported having any faculty with a PhD in evolution- ary biology.Lack of time in the curriculum and lack of faculty expertise are the main perceived impediments to increased teaching of evolution. We conclude that the role of evolutionary biology as a basic medical science should be carefully considered by a distinguished group of biologists and medical educators.In the meanwhile,undergraduate educators need to recognize that, for now at least, most future physicians must learn evolutionary biology as undergraduates if they are to learn it at all.

Keywords: Darwinian medicine,evolutionary biology,,curriculum

fforts to bring the principles of evolutionary aspects ofthe , thus perhaps accounting for Ebiologyto bear on the problems ofmedicine have grown rapidly rising rates ofallergic and autoimmune disorders rapidly in recent years (Williams and Nesse 1991, Ewald (Rook and Stanford 1998, Bach 2002). Although natural se- 1994,Nesse and Williams 1995, Stearns 1998, Trevathan et al. lection does not shape themselves, it is responsible for 1999, Greaves 2001). In the area ofinfectious , for in- many aspects ofbodily design that leave us vulnerable to stance, long-standing recognition ofantibiotic resistance has diseases. Major tasks for Darwinian medicine include ex- been augmented by new,sophisticated models ofhow selec- plaining why these vulnerabilities remain,despite the force of tion shapes increases,as well as decreases,in levels ofvirulence, ,and how this knowledge can assist medicine according to their benefits for (Ebert 1998, Levin and promote . et al.1999). Also,defenses against infection,such as fever The benefits ofusing evolutionary ideas to understand and immune responses, are now interpreted as the products disease are becoming widely recognized both in research, ofan evolutionary arms race in which stasis is likely to be where thousands ofrelevant reports have appeared,and in the fatal and effective defenses are likely to be costly and causes many new undergraduate courses on Darwinian medicine.In ofdisease in their own right (Ewald 1995). The maintenance the curricula ofmedical schools, however, the role ofevolu- ofsexual reproduction despite the huge costs ofhalv- tionary biology remains uncertain.A briefquestionnaire ing the proportion ofan individual’s genes in each offspring study conducted in the United Kingdom in 1997 reported re- (as compared with asexual reproduction) may be explained sponses from 20 ofthe 30 medical schools surveyed (Short by the benefits ofvarying the targets that pathogens attack 1994). The question “Is evolutionary theory regarded as rel- (Hamilton and Zuk 1982,Wilkinson et al.1998). In genetics, evant for the training ofdoctors?” was answered in the affir- old models ofmutation– selection balance are being aug- mative by 75 percent.Eleven UK schools reported having mented by systematic analysis ofthe selection forces that “teaching sessions in animal/ included in the may maintain the presence ofalleles that increase vulnerability medical curriculum,”and 18 included . to disease, whether by or other means. No comparable data are available for North American More broadly yet,physicians are now seeking not only prox- medical schools. To begin to fill this gap, we sent a one-page imate explanations for why some individuals get sick and letter and questionnaire to each medical school dean in North others do not but also complementary evolutionary expla- America listed by the Association ofAmerican Medical nations for why we all have bodies that are vulnerable to so Colleges as responsible for the medical curriculum ofhis or many diseases.For instance,many diseases result from the mis- match between our modern environment and the environ- ment in which we evolved (Eaton et al.2002). Examples Randolph M.Nesse ([email protected]) is a professor in the De- partment at the University of Michigan, Ann Arbor, MI 48104-2321. Joshua range from to myopia. Recent evidence sug- D.Schiffman ([email protected]) is in the Department of gests that the benefits ofmodern hygiene have serious costs at Stanford University School of Medicine in California. © 2003 in lack ofexposure to infections that stimulate inhibitory American Institute of Biological Sciences.

June 2003 / Vol. 53 No. 6• BioScience585 Education her institution. The survey, conducted under the auspices of scientific status ofevolutionary biology”and “concerns about the World Federation ofMedical Education, asked 30 ques- political controversy”were issues at only a few schools. Only tions that covered five areas: (1) medical school prerequisites, one item was cited by more than 5 percent ofthe schools as (2) topics in the required medical curriculum,(3) faculty a “major impediment”: “lack oftime in the curriculum,” resources, (4) deans’impressions regarding the importance which was cited by 31 percent. ofevolution education, and (5) reasons why increasing This study has several limitations.Although the sample was coverage ofevolutionary biology might be difficult.Responses incomplete,an inevitability because ofthe deans’busy sched- were received from 50 schools. ules,it was nonetheless large enough to convey an estimate Deans at 24 ofthese 50 schools (48 percent) answered ofthe amount ofevolutionary biology in the curricula of “yes”to the question “At your medical school,is evolution- North American medical schools and its perceived importance. ary biology regarded as important knowledge for physi- A more serious problem is the lack ofa method to determine cians?”However, only three schools require a course in whether respondents understood the questions; several noted evolutionary biology as a prerequisite for matriculation, and in the margins that they did not recognize some ofthe listed only two have “a distinct course or lecture sequence that pre- concepts, which, ofcourse, adds unreliability to the reports sents evolutionary biology as a basic medical science.”Among about the topics covered.The lack ofan accurate recognition the 30 complete responses to the question “Outside ofa spe- ofcertain topics may help explain the apparent discrepancy cific course on the topic, about how many lecture or contact between the high percentage ofschools that reported teach- hours are devoted to teaching [evolutionary biology]?”10 ing the somewhat technical topic oflevels ofselection (51 per- deans reported 0 hours; the median for the other 20 cent) and the very small percentage that reported covering responses was 4 hours. Only 8 (16 percent) schools reported elementary concepts such as (9 percent) and the having any medical school faculty with a primary specialty of distinction between proximate and ultimate explanations in evolutionary biology. (5 percent) (table 1). As shown in table 1, more than halfof the schools re- A more comprehensive study would require backing from ported covering core topics involving basic genetics and a major US medical education organization to increase the re- evolution.Evolutionary explanations for vulnera- sponse rate for a questionnaire that would require consider- bility to disease were covered in 10 to 25 percent ofschools, ably more time from respondents. The questionnaire would while fewer than 10 percent reported covering fundamental need to define the concepts in more detail, confirm respon- principles such as kin selection and the distinction between dents’understanding ofthem, and determine the coverage of proximate and ultimate explanations. each content area in each curriculum.An optimal study Table 2 summarizes responses to the question “Which of would go further and verify what is actually presented and the following factors would likely make it difficult for your what medical students actually learn.Such a definitive study medical school to incorporate or increase evolutionary biol- would be worthwhile. The information gathered here is suf- ogy teaching in the medical curriculum?”T wo reasons were ficient,however,to show that North American medical schools cited by more than halfof schools: “lack ofcurriculum time” do not teach evolutionary biology as a core basic science and and “lack offaculty expertise.”“Lack ofconfidence in the that their curricula fail to cover many fundamental evolu- tionary principles and concepts. The simplest explanation for Table 1.Percentage ofmedical schools reporting these shortcomings is that fewer than halfof the schools re- coverage oftopics related to evolutionary biology. gard evolutionary biology as important knowledge for physi- Topic Percent cians.A third ofthe deans said that “lack ofagreement about the relevance ofevolutionary biology”might make it difficult Antibiotic resistance 94 to augment teaching in evolutionary biology.These responses evolution 83 are not surprising: Few physicians have had a chance to learn Population genetics 79 evolutionary biology,and few medical schools have any fac- Selection for disease genes 72 ulty with specialized expertise in the subject.T ogether,these selection balance 55 factors have severely limited opportunities for medical edu- Levels of selection 51 cators to consider how evolution can be useful for medicine. Host–pathogen arms races 43 Another possible explanation could be that educators Novel environment causing disease 30 believe that evolution is already covered adequately in the Tradeoffs 26 undergraduate curriculum.T o evaluate this possibility, one Comparative 21 ofus (R.M.N.) informally surveyed first-year medical Defense regulation 20 students about their background in evolutionary biology. Life history evolution 19 Only about 15 percent ofentering students reported having Design flaws from path dependence 17 had a course in evolution,and even fewer reported familiar- Primate phylogeny 9 ity with current core issues in the field, such as levels of Kin selection 9 selection,the origins ofsex, and the evolution ofvirulence. Proximate/ultimate distinction 5 A study offirst-year medical students in Australia found that

586 BioScience • June 2003 / Vol. 53 No. 6 Education

64 percent had studied no evolutionary biology,and 27 national medical education leaders conclude that physicians percent believed that species did not evolve by natural selec- should learn at least the fundamentals ofevolutionary biol- tion (Short 1994). ogy as they apply to medicine,the gap could be filled by a com- A more proximate explanation for the absence ofevolu- bination ofnew undergraduate prerequisites, model medical tionary biology could be in the process that determines the curricula,and appropriate board examination questions to en- curriculum.According to interviews with medical educa- sure that medical graduates have a basic understanding ofevo- tors, members ofcurriculum committees often advocate for lutionary biology comparable to their understanding ofother increased time for their own content areas. Most schools basic medical sciences. have no faculty with expertise in evolutionary biology,which would naturally result in little (or no) curriculum time devoted to the topic. Acknowledgments Finally,a historical explanation may be important. In the We thank the deans who completed and returned the ques- early 20th century,Abraham Flexner’s famous report marked tionnaires that made this study possible and the World Fed- the beginning ofsystematic basic science education in med- eration ofMedical Education and its past president, Hans icine.At that time, evolutionary biology was in a period of Karle,for supporting this research. eclipse (Ghiselin 1969), so there was little reason to include it. Since the synthesis with genetics in the middle ofthe last References cited century,and subsequent major discoveries in and Alcock J. 2001. The Triumph of . New York:Oxford University molecular biology,the explanatory power ofevolution has Press. grown substantially (Mayr 1982,Alcock 2001). Only now,how- Bach JF.2002. Mechanisms of disease: The effect of infections on suscepti- bility to autoimmune and allergic diseases. New England Journal of ever,is it being applied systematically to medicine;one arti- Medicine 347: 911–920. cle reported over 1200 recent articles at the interface of Charlton BG.1997.A syllabus for evolutionary medicine.Journal of the Royal medicine and evolution (Stearns and Ebert 2001). Other Society of Medicine 90: 397–399. basic sciences that have been incorporated into the curricu- Eaton SB, et al.2002. Evolutionary health promotion.Preventive Medicine lum,such as genetics, have more direct applications to spe- 34: 109–118. cific clinical conditions.An evolutionary approach to disease Ebert D. 1998. of parasites.Science 282: 1432–1435. has yet to demonstrate that it is indispensable to finding new Ewald PW.1994.Evolution of Infectious Disease. New York:Oxford University ways to prevent or cure specific diseases, but it already has Press. major practical implications for some problems, including ———.1995. The evolution of virulence: A unifying link between para- vaccine design and antibiotic resistance (Nesse 2001, Stearns sitology and ecology.Journal of Parasitology 81: 659–669. Ghiselin MT.1969. The Triumph of the Darwinian Method.Berkeley: Uni- and Ebert 2001). Furthermore,such an approach provides the versity of California Press. same kind ofbasic foundation for understanding the body as Greaves M.2001. : The Evolutionary Legacy.Oxford (United King- physiology and anatomy do, and its perspective on the history dom):Oxford University Press. ofour species is parallel to what embryology provides for un- Hamilton WD,Zuk M.1982. Heritable true fitness and bright birds: A role derstanding individual development.Yet, as demonstrated by for parasites? Science 218: 384–387. this study, medical students neither come with a good prepa- Levin BR, Lipsitch M,Bonhoeffer S. 1999. Population biology,evolution,and ration in evolutionary biology nor do they learn it as a basic infectious disease: Convergence and synthesis. Science 283: 806–809. medical science. Mayr E.1982. The Growth of Biological Thought: Diversity, Evolution,and We conclude that the proper role ofevolutionary biology Inheritance. Cambridge (MA):Belknap Press. Nesse RM. 2001.How is Darwinian medicine useful? Western Medical Jour- in the medical education needs to be considered by medical nal 174: 358–360. curriculum committees, in consultation with evolutionary Nesse RM, Williams GC. 1995. Why We Get Sick. New York:Times Books. biologists (Charlton 1997, Nesse and Williams 1997). If ———.1997. Evolutionary biology in the medical curriculum—what every should know.BioScience 47: 664–666. Table 2.Percentage ofmedical schools reporting factors Rook GA,Stanford JL. 1998. Give us this day our daily germs. that make it difficult to incorporate teaching Today 19: 113–116. evolutionary biology. Short RV.1994. Darwin,have I failed you? Lancet 343: 528–529. Factor Percent Stearns S,ed.1998. Evolution in Health and Disease. Oxford (United King- dom):Oxford University Press. Lack of curriculum time 87 Stearns SC, Ebert D. 2001.Evolution in health and disease.Quarterly Review Lack of faculty expertise 53 of Biology 76: 417–432. Lack of funding 34 Trevathan WR, McKenna JJ,Smith EO,eds.1999. Evolutionary Medicine.New Lack of agreement about relevance 33 York:Oxford University Press. Wilkinson GS, Presgraves DC, Crymes L.1998. Male eye span in stalk-eyed Difficult finding/hiring qualified faculty 24 flies indicates genetic quality by meiotic drive suppression. Nature 391: Political controversy 11 276–279. Lack of confidence in scientific status Williams GW,Nesse RM. 1991.The dawn of Darwinian medicine.Quarterly of evolutionary biology 5 Review of Biology 66: 1–22.

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