Evolutionary medicine/Bibliography

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Works of Randolph M. Neese, M.D., University of Michigan

Journal articles

• Nesse RM: The evolution of senescence (letter). The New England Journal of Medicine, 310:660, 1984.

• Nesse RM (1984) An evolutionary perspective on psychiatry. Compr.Psychiatry 25:575-580.

• Nesse RM. (1988) Life table tests of evolutionary theories of senescence. Exp.Gerontol. 23:445-453 PMID 3250881.

• Abstract: The phenomenon of senescence requires both evolutionary and proximate explanations. The most widely accepted evolutionary explanation for senescence is that it never gets exposed to natural selection because environmental hazards kill all individuals before the age at which senescence causes decreased fitness. If this explanation is sufficient, wild populations should not demonstrate senescence, and their mortality rates should therefore remain constant during adult life, except when environmental causes of mortality have recently decreased. The alternative explanation for the persistence of the genes that cause senescence is that they have been selected for because they have pleiotropic effects that are beneficial early in life when the force of selection is strongest. Where this is the case, mortality rates should increase with age in wild populations. A method is described for using life table data to calculate an estimate of the intensity of selection acting on senescence in wild populations. This method is applied to a variety of life tables. The results suggest that pleiotropic genes may be important causes of senescence in some populations, but not in others. This has implications for research on the proximate mechanisms of senescence.

• Nesse RM. (1990) The evolutionary functions of repression and the ego defenses. J.Am.Acad.Psychoanal. 18:260-285.

• Wlliams GC & Nesse RM (1991) The dawn of Darwinian medicine. Q.Rev.Biol. 66:1-22. PMID 2052670.

• Abstract: While evolution by natural selection has long been a foundation for biomedical science, it has recently gained new power to explain many aspects of disease. This progress results largely from the disciplined application of what has been called the adaptations program. We show that this increasingly significant research paradigm can predict otherwise unsuspected facets of human biology, and that it provides new insights into the causes of medical disorders, such as those discussed below:

• 1. Infection. Signs and symptoms of the host-parasite contest can be categorized according to whether they represent adaptations or costs for host or parasite. Some host adaptations may have contributed to fitness in the Stone Age but are obsolete today. Others, such as fever and iron sequestration, have been incorrectly considered harmful. Pathogens, with their large populations and many generations in a single host, can evolve very rapidly. Acquisition of resistance to antibiotics is one example. Another is the recently demonstrated tendency to change virulence levels in predictable ways in response to changed conditions imposed incidentally by human activities.
• 2. Injuries and toxins. Mechanical injuries or stressful wear and tear are conceptually simpler than infectious diseases because they are not contests between conflicting interests. Plant-herbivore contests may often underlie chemical injury from the defensive secondary compounds of plant tissues. Nausea in pregnancy, and allergy, may be adaptations against such toxins.
• 3. Genetic factors. Common genetic diseases often result from genes maintained by other beneficial effects in historically normal environments. The diseases of aging are especially likely to be associated with early benefits.
• 4. Abnormal environments. Human biology is designed for Stone Age conditions. Modern environments may cause many diseases-for example, deficiency syndromes such as scurvy and rickets, the effects of excess consumption of normally scarce nutrients such as fat and salt, developmental diseases such as myopia, and psychological reactions to novel environments.

• The substantial benefits of evolutionary studies of disease will be realized only if they become central to medical curricula, an advance that may at first require the establishment of one or more research centers dedicated to the further development of Darwinian medicine.

• McGuire MT, Marks I, Nesse RM, & Troisi A. (1992) Evolutionary biology: a basic science for psychiatry? Acta Psychiatr.Scand. 86:89-96.

• Abstract: Evolutionary biology has much to offer psychiatry. It distinguishes between ultimate and proximate explanations of behavior and addresses the functional significance of behavior. Subtheories, frequently voiced misconceptions, specific applications, testable hypotheses and limitations of evolutionary theory are reviewed. An evolutionary perspective is likely to improve understanding of psychopathology, refocus some clinical research, influence treatment and help integrate seemingly unrelated findings and theoretical explanations

• Nesse RM & Berridge KC (1997) Psychoactive drug use in evolutionary perspective. Science 278:63-66. PMID 9311928.

• ’Abstract: Pure psychoactive drugs and direct routes of administration are evolutionarily novel features of our environment. They are inherently pathogenic because they bypass adaptive information processing systems and act directly on ancient brain mechanisms that control emotion and behavior. Drugs that induce positive emotions give a false signal of a fitness benefit. This signal hijacks incentive mechanisms of "liking" and "wanting," and can result in continued use of drugs that no longer bring pleasure. Drugs that block negative emotions can impair useful defenses, although there are several reasons why their use is often safe nonetheless. A deeper understanding of the evolutionary origins and functions of the emotions and their neural mechanisms is needed as a basis for decisions about the use of psychoactive drugs.

• Conclusion: Emotional capacities evolved to improve the Darwinian fitness of individuals as they seek resources and avoid dangers. The pursuit of emotion-associated goals tends to move organisms up a hedonic and adaptive gradient, but neurobehavioral systems are designed to maximize Darwinian fitness, not happiness, so our pleasures are often fleeting, and we experience much unnecessary suffering. The neurochemical mechanisms that mediate these states confer intrinsic vulnerability to substance abuse in environments where drugs are available. A better understanding of the mechanisms, origins, and functions of the emotions will enhance our ability to cope with substance abuse and our wisdom in making decisions about the therapeutic use of psychoactive drugs.

• Nesse R (1998) Emotional disorders in evolutionary perspective. Br.J.Med.Psychol. 71:397-415.

• Abstract: Understanding emotional disorders requires understanding the evolutionary origins and functions of normal emotions. They are special states, shaped by natural selection to adjust various aspects of the organism in ways that have tended to give a selective advantage in the face of the adaptive challenges characteristic of a particular kind of situation. They are designed to maximize reproductive success, not happiness. Negative emotions such as anxiety and low mood are not disorders, but, like the capacity for pain, evolved defences. Excessive anxiety or low mood is abnormal, but we will not have confidence about what is excessive until we understand their functions better than we do. Emotional disorders arise often from social emotions because of the conflicts inherent in social life, and because of the strategic advantages of demonstrating commitments to follow through on threats and promises. An evolutionary understanding of individuals in terms of their relationship strategies and the social emotions offers great promise for psychotherapists.

• Nesse R. (1998) Darwinism and psychiatry. Harv.Ment.Health Lett. 14:5-7. PMID 15344231.

• Nesse RM & Williams GC .(1998) Evolution and the origins of disease. Sci.Am. 279:86-93.

• Nesse RM (1999) Proximate and evolutionary studies of anxiety, stress and depression: synergy at the interface..Neurosci.Biobehav.Rev. 23, p 895-903. PMID 10580304.

• Abstract: While enormous progress has been made in unraveling the proximate physiological mechanisms that account for anxiety, stress, and low mood, these states continue to give rise to considerable conceptual confusion. This is, in part, because proximate studies have neither been adequately distinguished from, nor integrated with, evolutionary explanations for the adaptive functions of anxiety, stress, and mood. A complete biological explanation that incorporates both proximate and evolutionary explanations will be of great value to better define the border between normal and pathological, to help to explain why pathological anxiety and depression are so common, and to provide a much-needed basis for sensible decisions about when different pharmacological manipulations are likely to be helpful or harmful. Ideally, evolutionary considerations should provide a conceptual framework within which the biological significance of the proximate mechanisms can be better understood, and the proximate findings should provide tests of evolutionary hypotheses. Studies at the interface between evolutionary and proximate explanations will be difficult, but important to better understand individual differences in vulnerability and the etiology of diseases that result from dysregulation of anxiety and mood.

• Concluding Paragraph: The focus of this article has been the adaptive significance f anxiety, low mood and stress, so to prevent misunderstanding, it is important to clearly state that much anxiety and depression results from diseases such as major depression and panic disorder. Furthermore, much physical, and probably mental, illness results from the complications of the stress response. The search for the etiology of these disorders is a high priority. The argument here does not undermine the hard-won recognition that these disorders really are diseases. It does, however, suggest that, like chronic pain and febrile seizures, they probably often involve dysregulation of a normal defense. If that is correct, it implies the need to use special research strategies that begin by elucidating the normal mechanisms that mediate the defense, and then proceed to study the mechanisms that regulate the defense, and finally try to understand the etiological factors that disrupt the normal regulation mechanisms. Understanding the proximate mechanisms that normally regulate these defenses, from molecules to neurons to the transduction of social cues, will provide a solid foundation for understanding why and how they become dysregulated. Evolutionary approaches that focus attention on their normal functions, how they were shaped by natural selection, and how they are regulated, will be essential in this enterprise.

• Nesse RM. (2000) Natural selection, mental modules and intelligence. Novartis.Found.Symp. 233:96-104. PMID 112769132.

• Abstract: The question of whether intelligence is one trait or many has exercised several generations of researchers, but no consensus is in sight. Evolutionary psychology, with its emphasis on domain-specific mental modules, seems to offer hope for advancing understanding of this question. We know that the mind has been shaped by natural selection to maximize reproductive success. This tells us what the mind must do--it must solve the adaptive problems that the organism confronts. However, whether this functional capacity is manifest in congruent anatomic, physiological, genetic, cognitive or psychometric structures is another matter. Examination of how natural selection shaped other mechanisms suggests that knowing functional demands provides only modest guidance as to the structure of mechanisms. None the less, it remains simultaneously clear that these mechanisms are not entirely general, but have been shaped to cope with specific challenges. Our metaphors for the mind, whether as a digital computer or a Swiss army knife, are misleading because computers and tools are products of intelligent design. In contrast, minds are products of natural selection whose intertwined components are products of incorporated genetic mutations whose effects are widespread and constrained by historical precedents. Our tendencies to describe the structure of the mind in terms of discrete components make it difficult for us to comprehend the mind as a mind. One antidote may be to minimize metaphorical descriptions of postulated structures of mind and focus instead on its function.

• Nesse RM. (2000) Is depression an adaptation?.Arch.Gen.Psychiatry 57:14-20. PMID 10632228.

• Abstract: Many functions have been suggested for low mood or depression, including communicating a need for help, signaling yielding in a hierarchy conflict, fostering disengagement from commitments to unreachable goals, and regulating patterns of investment. A more comprehensive evolutionary explanation may emerge from attempts to identify how the characteristics of low mood increase an organism's ability to cope with the adaptive challenges characteristic of unpropitious situations in which effort to pursue a major goal will likely result in danger, loss, bodily damage, or wasted effort. In such situations, pessimism and lack of motivation may give a fitness advantage by inhibiting certain actions, especially futile or dangerous challenges to dominant figures, actions in the absence of a crucial resource or a viable plan, efforts that would damage the body, and actions that would disrupt a currently unsatisfactory major life enterprise when it might recover or the alternative is likely to be even worse. These hypotheses are consistent with considerable evidence and suggest specific tests.

• Conclusion: Is depression an adaptation? At present, we do not have the evidence needed to say for sure. However, it seems likely that low mood and related negative affects were shaped to help organisms cope with unpropitious situations. Some negative and passive aspects of depression may be useful because they inhibit dangerous or wasteful actions in situations characterized by committed pursuit of an unreachable goal, temptations to challenge authority, insufficient internal reserves to allow action without damage, or lack of a viable life strategy. However, it is essential to emphasize that many depressions are clearly disease states: some caused by dysregulations of negative affect and others by brain defects unrelated to low mood. The fact that low mood, and perhaps some depression, may be useful should not distract attention from recognition that depression is one of humanity's most serious medial problems.108 A deeper understanding of the adaptive significance of low mood and depression will improve our ability to prevent and relieve both mood disorders and low moods that are normal, but unnecessary.