Sandra Bream Andersen has just contacted us to let ISEMPH members know that the Lorentz Center in Leiden is hosting a workshop they think might be of interest to many, the full title of which is “Microbial Darwinian Medicine: A Workshop at the Interface of Medicine and Microbial Eco-Evolutionary Biology”. The workshop will be held between August 14th and 17th this year, just prior to the nearby ISEMPH annual meeting in Groningen. The link will take you to registration or allow you to submit an application to participate.
Immigration has become one of the most controversial and vitriolic issues of recent times, whether concerning illegal immigration of Mexicans into the US; economic migrants throughout the European Union; or refugees fleeing starvation or draconian political regimes throughout Africa and the Middle East. Tensions run high with repeated claims that such immigrants represent an uncontrollable tide capable of swamping the country of arrival; that immigrants take peoples’ jobs and livelihoods away from them; that they pose a security risk because terrorists hide in their ranks; and that they impose unsustainable strains on health and welfare services. Of course all these arguments – misguided, ignorant or prejudiced though they be – are assumed to be the product of conscious thought processes even if they are motivated by deep-seated fears and even if they are fanned by right-wing reactionary commentators using inflammatory plague-like metaphors: We are being “swamped by a tide” or immigrants are sweeping across borders “like rats and cockroaches”, for instance.
Now, three political scientists, Lene Aaroe and Michael Bang Peterson, from Aarhus University, and Kevin Arceneaux from Temple University, have attempted to broaden our understanding of such xenophobia by implicating totally unconscious processes set in train by our immune systems through their links to the brain and behaviour. Their paper is published in American Political Science Review and titled “The Behavioral Immune System Shapes Political Intuitions: Why and How Individual Differences in Disgust Sensitivity Underlie Opposition to Immigration”. The full paper is behind a paywall but a pdf of the paper exists in the public realm courtesy of the University of Aarhus. Using population samples from the US and Denmark they present and test, they explain, the way the behavioural immune system (BIS) connects disgust, a powerful basic human emotion, to political attitudes through psychological mechanisms evolved to protect humans from disease. These mechanisms work outside of conscious awareness, they say, and in modern environments they can motivate individuals to avoid intergroup contact by opposing immigration. Specifically, the more sensitive or hyper-vigilant the behavioural immune system is in any individual, the more it will underlie their opposition to immigration.
This is a very controversial area but we think it well worth airing it. Evmedreview invited Riadh Abed, the chairman of the Evolutionary Psychiatry Special Interest Group of the Royal College of Psychiatrists, in the UK, to write a commentary on Aaroe et al’s paper, which follows, and we invite all readers to comment on this paper.
A new and interesting piece of research has been published this month in the influential American Political Science Review. The research adds a further line of enquiry to the troubled and thorny question of attitudes to immigrants and to immigration. It looks at the potentially important but hidden factor that influences peoples’ (and politicians’) preferences when it comes to formulating or influencing policies dealing with immigration. The main thesis of the article is that the immune system has a behavioural component that aims to prevent exposure to pathogens and importantly this system (the Behavioural Immune System, henceforth BIS) operates entirely outside conscious awareness. The BIS utilises the emotion of disgust to motivate avoidance of potentially infected objects and people. The system seeks to keep the ‘unclean’ outgroup members away from the ‘clean’ ingroup.
Of course, in such politically sensitive research into the presumed biological roots of xenophobia and intolerance, it is important to distinguish at the outset between description and prescription. Also, it is important to be aware of the scope for misunderstanding and misinterpretation of the application of evolutionary principles to ethnic differences given the negative historical legacy of Social Darwinism. The authors were clearly aware of the sensitivities surrounding their research and have given a detailed and cogent explanation of the value of such work.
The ideas and hypotheses they sought to test were not new in themselves. The link between disgust, pathogen avoidance and xenophobia has been known for some time. The evolutionary roots of linking outgroup members to dangerous pathogens most likely relates to the well documented fact that our immune system is most effective against local pathogens rather than exotic ones. One of the best known historical examples of the devastating effects that novel pathogens can have is the fate of the indigenous populations of the New World when invaded by the Spanish Conquistadors (for a detailed description see Jared Diamond’s best-seller Guns, Germs and Steel).
The authors conducted a meta-analysis of 16 published studies that tackled the issue of pathogen avoidance and attitudes to immigrants and xenophobia in general. Most studies found a positive correlation between disgust, fear of disease and negative attitudes to immigrants but they concluded that the quality of the data was generally unsatisfactory due to a range of flaws in these studies’ design. They therefore set out to address these flaws. The study populations were selected from 2 countries namely Denmark and the United States and the study involved both questionnaire and physiological data. Although both countries share a liberal democratic political system there are important differences. The US is a country of immigrants with a high level of diversity and relatively low levels of social welfare (by western standards) whereas Denmark has a stable and homogeneous population with high levels of social welfare spending which makes immigration particularly costly.
They assumed that the sensitivity of the BIS varies across the population and they tested the hypothesis that individuals with high sensitivity are more opposed to immigration. They also, rather ingeniously, tested the hypothesis as to whether disease protection deactivates the link between anti-immigration attitudes and the BIS.
In answer to their first hypothesis their conclusion was that there was a robust positive relationship between a highly sensitive BIS and opposition to immigration and that this correlation held even after controlling for education and ideology and was evident on both questionnaire and physiological measures. To answer their second hypothesis regarding the possibility of deactivating the link between the BIS and anti-immigrant attitude they used a scenario that either included or didn’t include handwashing, with simple handwashing being the disease protection behaviour. Interestingly, the simple addition of handwashing to the scenario appears to attenuate the effect of the BIS and reduce the degree of the subjects’ xenophobia. Their conclusion was that the link between disgust and the BIS sensitivity and the anti-immigrant attitudes was not a spurious finding. Their third hypothesis was that cultural familiarity (as a proxy for ingroup membership) would reduce anti-immigrant attitudes and this was indeed supported by their findings.
The authors contend that their study has plugged a gap in the literature by providing high quality data in support of a link between a sensitive BIS (manifested through a high propensity to disgust) and anti-immigrant attitudes and demonstrated that it operates independently of education, income and ideology.
They also point out that the BIS can create obstacles in the face of attempts towards the emergence of tolerance and greater integration of new immigrants.
Can such research make a difference for educators and policy-makers? The authors believe it can but as with many interesting evolutionary findings in the biological and social sciences, such data may be one or two steps removed from practical application. However, if this is a real effect as the authors have contended in this well-designed study, then it would foolish not pay attention to it.
The International Society for Evolution, Medicine & Public Health has just announced the winner of the 2017 Omenn Prize. It is Alison Feder, and her colleagues, of Stanford University, for their paper in eLife titled “More effective drugs lead to harder selective sweeps in the evolution of drug resistance in HIV-1“. The Prize Committee included Jim Bull, Antonium Rokas and Grazyna Jasienska and was overseen by Andrew Reed. The winner receives a prize of $5000, courtesy of the generosity of Gilbert Omenn, and an invitation to present their paper at the annual meeting of the Society in Groningen in August. Congratulations to Alison!
Some of our readers may be interested in considering this advertisement for a lectureship at the University of Cambridge at the intersection of evolutionary biology with medicine. It is an Unestablished Lectureship in Evolution and Medicine based in the Department of Zoology and Sidney College and runs, initially, for 3 years. Details are available at the following link: http://www.jobs.cam.ac.uk/job/13493/
Evmedreview is very pleased to feature a paper on evolutionary nephrology by Robert L. Chevalier. Robert joined the University of Virginia in 1978 where he established the now internationally recognized Division of Pediatric Nephrology. Since 2010 he has devoted himself full-time to studying chronic kidney disease progression from birth to senescence. Finding his study limited by a conventional training in medicine and physiology he turned to evolutionary medicine for explanations based on ultimate causes. We believe this paper is the first comprehensive application of evolutionary medicine to understanding progressive chronic kidney disease. Chevalier traces his evolutionary perspective back to Homer W. Smith who did pioneering work on kidney evolution in the late 1930s. In his book From Fish to Philosopher, Chevalier says, Smith argued that the complex structure of the kidney can be explained by a series of evolutionary adaptations in our vertebrate ancestors, who transitioned from marine to fresh water environments and ultimately to survival on land. Written by the leading American renal physiologist of the mid- 20th century, says Chevalier, that book revealed how an evolutionary perspective explains the dependence of renal excretory function on filtration of 180 liters of plasma per day and reclamation of 99% of the filtrate. Many of the early advances in renal physiology were based on animal studies that required an understanding of evolution to apply the results to human beings.
Why is evolutionary medicine important? According to Chevalier, the primary challenge to the adoption of an evolutionary approach to disease rests on the practice of medicine itself: physicians are charged with the responsibility for diagnosing and treating a particular disorder in an individual patient, a process that appears far removed from evolutionary concerns. However, the history (present illness, past history, and family history) is the key component in diagnosis. Seeking concordance with established medical sciences (genetics, anatomy, physiology, biochemistry), evolutionary medicine relies on evolutionary biology to create a “deep” history of human populations. The rationale for the evolutionary perspective is that rather than causing disease, our evolutionary history determines our risk of disease in a given environment, a context that overlaps with public health, global health, and health care disparities.
The featured image illustrates Homer Smith’s account of the more important steps in the evolution of the vertebrate kidney in relation to saltwater (darkly shaded) and freshwater (lightly shaded) environment. The evolutionary tree is followed through primitive fish, amphibians, reptiles, birds and mammals showing the adaptation to a terrestrial environment.
Chevalier’s paper is published in Kidney International Reports and simply titled Evolutionary Nephrology. To whet your appetites here is the abstract:
“Progressive kidney disease follows nephron loss, hyperfiltration, and incomplete repair, a process described as “maladaptive.” In the past 20 years, a new discipline has emerged that expands research horizons: evolutionary medicine. In contrast to physiologic (homeostatic) adaptation, evolutionary adaptation is the result of reproductive success that reflects natural selection. Evolutionary explanations for physiologically maladaptive responses can emerge from mismatch of the phenotype with environment or from evolutionary tradeoffs. Evolutionary adaptation to a terrestrial environment resulted in a vulnerable energy-consuming renal tubule and a hypoxic, hyperosmolar microenvironment. Natural selection favors successful energy investment strategy: energy is allocated to maintenance of nephron integrity through reproductive years, but this declines with increasing senescence after ~40 years of age. Risk factors for chronic kidney disease include restricted fetal growth or preterm birth (life history tradeoff resulting in fewer nephrons), evolutionary selection for APOL1 mutations (which provide resistance to trypanosome infection, a tradeoff), and modern life experience (Western diet mismatch leading to diabetes and hypertension). Current advances in genomics, epigenetics, and developmental biology have revealed proximate causes of kidney disease, but attempts to slow kidney disease remain elusive. Evolutionary medicine provides a complementary approach by addressing ultimate causes of kidney disease. Marked variation in nephron number at birth, nephron heterogeneity, and changing susceptibility to kidney injury throughout the life history are the result of evolutionary processes. Combined application of molecular genetics, evolutionary developmental biology (evo-devo), developmental programming, and life history theory may yield new strategies for prevention and treatment of chronic kidney disease.”