How can evolutionary theory be used to solve real-world health problems?

In this essay, I argue evolutionary theories can be used by global health policymakers to design policy that are locally contextualized solutions in the global epidemic of obesity. Specifically, the life histories approach and obesogenic environments hypothesis in normative definitions of obesity and metabolic syndrome(MetS), despite different anthropometric norms in different ethnic populations. Even though evolutionary theory often operates on a population level, I argue the evolution of evolutionary theory, in centering aesthetics, and individual experiences through the ‘beauty happens’ hypothesis, could be used in reshaping our goals, and the definition of pathology to begin with.

Obesity as real problem

Obesity is a ‘real’ problem in its significance(OED, 2024b) on global, national and individual levels. On an individual level it contributes significantly to mortality with increased risk of type 2 diabetes mellitus and cardiovascular disease(CVD), can affect bone health and reproduction, and increases the risk of certain cancers(WHO, 2024). On a global level, obesity is the largest and fastest growing health problems in the world. In 2022, 1 in 8 people in the world were living with obesity. Worldwide adult obesity has more than doubled since 1990, and adolescent obesity has quadrupled, and is increasing in every part of the world.

The International Diabetes Federation(IDF) in 2006 released a ‘new world-wide definition’ as a consensus statement from other professional health organisations including the World Health Organisation(WHO), The European Group for the Study of Insulin Resistance, and the National Cholesterol Education Program, from the United States(US). Even though professional health organistions had agreement on core components on MetS on obesity, inuslin resistance, dyslipidemia and hypertension, they employed different clinical criteria. The IDF stated the main motivation was the ‘strong need for one simple definition/diagnostic tool for clinical practice which could be used relatively easily in any country by any physician’ to ‘allow comparison of the prevalence of the syndrome in different populations and its relationships with various health outcomes’(Alberti, Zimmet and Shaw, 2006).

Defining Obesity through ethnicity-specific statistics

Anthropometrics is ‘the science that defines physical measures of a person’s size, form, and functional capacities’(NIOSH, 2022). One of the most popular anthropometry measures is the Body Mass Index (BMI) which is a person’s weight divided by the square of their height. BMI can be used in the diagnosis of obesity and is an indicator of body fat(WHO, 2024). Subsequently, in the consensus definition waist circumference(WC) was instead included as an indicator for central obesity, distinguishing intra-abdominal fat from subcutaneous fat, which is a more precise predictor for MetS. The waist circumference must be measured under specifics techniques ‘in a horizontal plane, midway between the inferior margin of the ribs and the superior border of the iliac crest(Alberti, Zimmet and Shaw, 2006). With recognition that different ethnic populations have different anthropometric norms, and that ‘(statistics) are normative in the sense that they make the norm and make us take it into account’(Laet and Dumit 2014:74), the IDF defines obesity through WC measurements that are ethnic group specific(Figure 1). Ethnicity refers to populations with shared social and cultural characteristics, backgrounds, or experiences(NCI 2011). The IDF recognized that the same WC measurement in different populations might be associated with different odds of CVD(Alberti, Zimmet and Shaw 2006). For instance, in East Asian populations in Japan and Singapore, an individual with a significantly smaller WC might have a higher rate of CVD than in a population from Europe(Banerjee and Misra 2007).

The emergence of obesity as a disease entity, Annemarie Jutel, a medical sociologist from New Zealand, argues can be explained by two phenomena. Firstly, the importance accorded to measurability in the establishing definitions of health and disease. Measuring an individual’s body weight, and the ability to express the results in standardised units, allows physicians to track progress. With a ’description of normality and a delineation of the bounds of normal build’, concepts of difference and deviance are also subsequently naturalised(Jutel 2006:2272). Secondly, the emphasis that ‘Western’ society (which Jutel implicitly defines as affluent, White-majority countries) places on normative appearances(Jutel 2006:2270). The departure from the standard of beauty, be it one of plumpness or of thinness, Jutel argues, leads to concern from in social institutions(Jutel 2006:2272).

Normality as real-world problem

‘Despite evidence-based policy recommendations to halt and reverse obesity rates over nearly three decades internationally, recommendations have yet to translate into meaningful and measurable change’(Swinburn et al. 2019), The Lancet commission writes. I identify the problem not just with the real rise in prevalence of obesity, but the real-world problem of normativity of bodies in impeding the implementation of policies at the healthcare provider level(OED, 2023). ‘Normativity’ is defined as entails that some action, attitude or mental state towards a state one ought to be in(Darwall 2016). The IDF’s creation of ethnic-specific norms, while attempting to solve variability, has created new problems in its wake.

Statistics are a self-fulfilling prophecy, Laet and Dumit American anthropologists, argue in that it creates healthy bodies. Ethnic-specific waist circumferences, are also a self-fulfilling prophecy in that ethnic-specific waist circumferences fossilises differences between ethnicities. Laet and Dumit use the example of calorie graphs that have been categorized by sex, superimposed upon one another, to illustrate the human range of calories, and the vast overlap between the sexes(Figure 2). By emphasizing differences between ethnicities through ethnic-specific health policy, the policy has the potential to cause harm because it fossilizes these differences as biological, which health professionals often conflate as genetic, definition of race(Gravlee 2009), and hence justifies the perpetuation of racism within medicine(Horton 2017).

With ethnic-specific WC, the same visual and perceptual preferences on normative appearances in Western populations that imposes moral judgements onto individuals within a community, are now transposed onto diverse populations. An individual physician’s aesthetic judgements contains concealed premises of their moral positions and aesthetic judgements about how an individual ought to look(Stafford, Puma and Schiedermayer 1989). Healthcare professionals have shown to display high levels of anti-obesity bias, and hence obese patients receive lower quality care, or fear negative judgements and mistreatment in clinical settings(Alberga et al., 2019). International guidelines that report certain ethnic populations are naturally more likely to be obese than others, legitimises the transfer of stigma that is imposed onto an individual obese body, to that of an entire ethnic population. Throughout the biomedical sciences, ethnicity tends to be conflated with nationality(Bhopal, 2013). Hence, even though the IDF guidelines includes a caveat that ‘ethnicity should be the basis for classification, not the country of residence’, the data sources in which they derive these ethnic-specific measurements are from geographically distinct countries. With the recognition of obesity as a global phenomenon, with high prevalences in middle and lower income countries, Alexandra Brewis, a New Zealand-American anthropologist, (Brewis, SturtzSreetharan and Wutich, 2018) finds evidence of consequent rise of weight-related stigma, with similar damage to the well-being of individuals. Statistically, the ‘fattest’ nations by prevalence of obesity are in South America, the Middle East and Africa(Noubiap et al., 2022). Hence, ethnicities and countries which suffer the most from obesity, tend to suffer from a double whammy of also being blamed for their obesity, suffering stigma.

Evolutionary Pressures, Not Ethnicity

Broadly, evolution refers to the movement or change in position, the process of revealing, and development(OED, 2024a). In biology, evolution is defined as ‘the change in the inherited traits of a population of organisms through successive generations’(Forbes and Krimmel, 2010). Evolutionary thinking in medicine is the application of basic evolutionary principles derived from the science of biology to understand human susceptible to disease. Evolution is understood through adaptation by natural selection, which Darwin describes in The Origin of Species by Means of Natural Selection(Darwin 2019(1859)) as ‘a non-random difference in reproductive output among replicating entities, often due indirectly to differences in survival in a particular environment, leading to an increase in proportion of beneficial, heritable characteristics within a population from one generation to the next’(Gregory 2009). Adaptation is ‘the process by which populations of organisms evolve in such a way as to become better suited to their environments as advantageous traits become predominant’(Gregory 2009). An evolutionary approach to health and disease addresses how our history as a species, and individual development, within specific environmental context can shape susceptibilities over the life course, considering how major changes in human lifestyle have altered the epidemiological nature of illnesses that can afflict us(WHO, 2024). Evolutionary theory builds layers of complexities that can fundamentally reshape the way professional health organisations design interventions.

‘Making global…charts may be an attempt to confine a ghost in a wire-mesh cage’(Laet and Dumit, 2014:84), Laet and Dumit argue that the effort to standardize the absolute environments, professional health bodies, like the IDF, broaden sites as baseline for the study. Instead, Laet and Dumit argue that ‘material circumstances may be more telling about their prospective health and growth than their adherence to any generalized chart’(Laet and Dumit, 2014:84). Understanding evolutionary theory can deepen our understanding on why differences between populations exist, moving beyond the mere identification of differences. Evolutionary theory hence offers evolutionary selective pressures as an alternative grouping of people into a population(Hacking 1999), rather than ethnicity, which is a reductive, static category. By viewing ethnicity as a the primary definition as distinct sets of bodies, the IDF’s diagnostic criteria, intentionally or not, leaves out other matrices, and other aspects of nutrition that will ‘remain hidden they do not receive the public, academic or policy attention they deserve’(Laet and Dumit 2014:78). For instance, the thrifty genotype hypothesis(Wells 2007) are genotypes that bestow superior energy efficiency such that energy balance equation is shifted heavily towards energy intake as opposed to energy expenditure. Taking a historical view, since the advent of agriculture 10,000 years ago, cycles of famine and abundance selected for thrifty genes that enabled the building of fat reserves and maintain fertility during periods of famine. Hence, the theory provides an explanation for why traditionally disadvantaged, populations that have faced exploitation of food resources, the high obesity prevalence in lower and middle-income countries. In South America, this theory have also been mapped onto mathematical models that have shown the change in allele frequency corresponds to periods of famine(Reales et al. 2017). Similarly, in a Dutch population that one does not typically associated with obesity, the thrifty genotype hypothesis can explain why children that were born during the 1944 Dutch famine were more predisposed to obesity. Evolutionary theory, then helps to form a line of reasoning that connects the Netherlands to South America. Hence, categorisation of risk profiles for MetS, rather than relying on mere ethnicity to interpret anthropometrics, can now take into account measures across time and geographies. The approach to take into account evolutionary selective pressures, deepens our understanding to be more accurate, focusing on causation rather than correlation, providing an opportunity to fundamentally redesign public health interventions. This reduces the harms prejudices that are attached to static categories can cause onto populations, resisting the urge to place people on a graph or a category into a singular statistical data point.

Beauty Happens: The Evolution of Evolution

Returning to Jutel’s conception of the formation of obesity as a clinical disease through departure on normative standards of beauty, it would be incomplete to discuss obesity without the role of physical appearances. Beauty Happens is an evolutionary theory that centers aesthetic choices of individuals popularised by Richard Prum, a renowned evolutionary biologist. In The Evolution of Beauty, Prum argues that Darwin’s theory of evolution is more than natural selection(Prum, 2018). In The Descent of Man, and Selection in Relation to Sex, Darwin also argues evolution is also selection by aesthetics through mate choice. In the process of choosing what they like, choosers evolutionarily transform both the objects of their desires and the form of their own desires’(Prum 2018). Contrary to natural selection, Prum argues organisms can choose beauty for beauty’s sake, rather than as a signaller of underlying health or reproductive potential.

Could the ‘Beauty Happens’ hypothesis add a layer of complexity to disease, decoupling weight from health, in explaining paradoxes where obesity does not necessarily correlate to the same logic of pathology? As suggested by IDF guidelines, ‘Asians’ do not necessarily require the same WC for the same risk of CVD as opposed to an individual from a different population. Hence, the IDF has adjusted normative value of a pathological WC accordingly. In South Korea, ethnography on beauty and cosmetic surgery, have shown have standards of beauty towards a thin physique, narrow jaw, pointy nose have been strongly shaped through neoliberal notions of self-improvement, predatory advertisements and popular television series(Lee, 2012). This provides an alternative perspective to view pathology, in that mate choices for thinness, have produced thinness, rather than thinness as an indicator for health. On the contrary, the ‘Beauty Happens’ hypothesis depathologise obesity in Hispanic populations. The ‘Hispanic paradox’ describes the phenomenon where even though Hispanic men and women in the US have higher rates of obesity when compared to non-Hispanic white residents, Hispanic individuals actually have lower rates of CVD mortality(Gomez, Blumer and Rodriguez, 2022). Ethnography on the cultural meanings of weight in a Puerto Rican community in Philadelphia notes that obesity is not stigmatised, and instead is viewed as attractive(Massara 1979). In fact, researchers have shown mice models have shown that metabolic profile can be disentangled from obesity, in that mice that can weigh five times the normal weight of a mice, but have a similar metabolic profile to a ‘normal sized’ mouse(Kim et al., 2007). Hence, obesity might not a pathology, not of poor health but rather a mere result of aesthetic choice.

Conclusion

In this essay, I have argued that evolutionary theory can reform ways of categorising risk profiles, and our fundamental assumptions of pathology. Evolutionary theory at its core adds dimensions to the way health policymakers understands the world, bodies not as static entities, but through both space and time. In my conclusion, I hope to turn that evolutionary theory unto health policymakers themselves.

Research internationally(Brewis et al., 2011; Brewis, SturtzSreetharan and Wutich, 2018) have showed 'globalisation of fat stigmas'(Figure 3). Ethnography has showed that with the spread of American media, there has been a pathologisation of heaviness, in Fiji leading to skyrocketing rates of eating disorders, that didn’t previously exist(Becker, 2004). In our rush to pathologise fatness, we have uncritically valorised thinness, which ironically showed higher mortality than individuals who are overweight but not obese(Flegal et al., 2005). Interventions might have inadvertently gotten the order wrong, in that our aesthetic choices are what shapes our bodies, but not our health. In a way, public health interventions done today, are a form of evolutionary pressure too, impacting the health on the future.

If evolutionary theory in and of itself can undergo evolution, so can global health policymakers evolve away from their fossilised reliance on normative bodies. 

Figures

Figure 1 Country/ethnic-specific values for waist circumferences from Alberti KG, Zimmet P, Shaw J. Metabolic syndrome -a new world-wide definition. A Consensus Statement from the International Diabetes Federation. Diabet Med. 2006 May;23(5):469-80. doi: 10.1111/j.1464-5491.2006.01858.x. PMID: 16681555.

Figure 2 Calorie graphs of superimposed sex-graphs from Laet and Dumit, “Curves to Bodies – The Material Life of Graphs.”

Figure 3 Map showing weight stigma throughout the world from Brewis, Sturtz Sreetharan, and Wutich, “Obesity Stigma as a Globalizing Health Challenge.”

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