Population Health

The pursuit of health research by human biologists and biological anthropologists has been part of those disciplines for many years. Health and disease topics were included in the first edition of the classic textbook, Human Biology (Harrison et al 1964), and its following two editions, and its recent counterpart (Stinson et al 2000). Despite this long tradition of health and disease studies in our fields, there has been an increase in studies explicitly asking questions about biocultural health determinants over the last 15–20 years. Some scholars in human biology and biological anthropology spend all their efforts trying to provide answers to health and disease questions. For example, both Prof. Noel Cameron and I, who became Co-Editors of our journal in January 2006 (joining Olga Rickards), study health and disease as a major part of our research programs. This editorial attempts to inform our readers about population health, link it to more standard scientific questions in human population biology, and serve as an invitation for our readers to consider incorporating these ideas in their manuscript submissions to our journal.

The phrase population health has been used with increasing frequency in scientific publications and research training programs in the last decade (e.g., Murray et al 1996, 2002, Robert Wood Johnson Foundation; http://www.healthandsocietyscholars.org/). The broad objective of population health is to combine interdisciplinary etiologic research on the social, environmental and biological determinants of heterogeneities in health and disease, with detailed inferences from such research about ways to reduce health inequalities within and across populations. Population health perspectives try to link a multi-level array of causal factors to health variations to eliminate health disparities within societies. I would argue that population health also includes intervention studies and the necessary formative, translational and implementation research necessary to develop and determine if public health interventions are efficacious and cost effective in defined populations.

The increase over the last two decades in explicit population health research by human biologists can be attributed to two major causes. First, studies of morphological and physiological variations and adaptations in specific human groups that had been undertaken with a predominant evolutionary, and an implied genetic, orientation became more concerned with understanding how such variations were associated with social environmental factors. As larger study samples were measured and socio-cultural variables were included, scholars came to see (1) how individuals on a continuum of biological values could be classified as less functionally able, unhealthy or in a clinically defined disease status, and (2) that even simple assessments of socio-economic status were strongly related to the distributions of the morphological, physiologic and health traits. Thus, human biologists became more interested in poverty and disease, while continuing to emphasize a complex adaptive framework of evolutionary factors interacting with contemporary social and economic environments. Such studies had been a part of human biology and bioanthropology, as indicated above, but more scholars now focused most of their work on disease and became trained and skilled in measuring health and disease.

Second, because of the rapid increases in government support for disease research, external financial support for human biology research became more oriented to descriptive and etiologic health and disease research. It became harder to obtain external support for studies to describe human biological variations in defined ethnic groups with evolutionary and adaptive explanations. More human biologists began to seek and receive scientific grants asking primarily health and disease oriented questions. This change can be informally called the ‘medicalization’ of human biology and bioanthropology, as one colleague described it to me. Of course, similar trends occurred in all the social sciences, as public research funds became more scrutinized for their contribution to solving societal problems.

Although the forces briefly outlined above have exerted their influences and led to the extension of human biology and biological anthropology research into studies of human health, critiques have focused on the remaining conceptual and methodological work (Goodman and Leatherman 1998; Hahn 1999; Panter-Brick and Fuentes 2007). Population health, as defined above, offers a way for human biologists to continue the interdisciplinary, holistic, community based movement towards health and disease research.

It is important to state what I think are some of the advantages of a population health perspective for human biology. We are in the midst of this change in our research questions, but more attention to these issues may lead to a greater recognition of our potential contributions. First, we must change our research and training from a view of describing the health of a particular population, usually an ethnically, linguistically and geographically defined population. Characterizing an entire population's health status becomes more dubious from an etiologic perspective as this de-emphasizes or denies substantial heterogeneities in health and their connections to social factors. Such normative descriptions feed into older notions of ethnic group specific health conditions with all the potential for sloppy thinking about genetic influences, labeling and stigmatization. (This should not negate studies based on ultimate evolutionary influences which investigate in detail genetic susceptibilities and gene-environment interactions.)

Second, we must continue our increasing attention conceptually to socio-economic differences within populations due to economic development and globalization. Human biology is well suited to utilize social science concepts and methods in a search for explicit connections with health and biology in populations. Collaborations with scholars and training our students to incorporate socio-economic, historical and political, and even psychosocial processes should be standard. Minimally, we should be careful now to uncritically use concepts such as ‘traditional way of life’ in causal inferences. Such concepts mask substantial social and health heterogeneities that we can measure and include in our deeper contextual explanations of biological variations and their causes. Using simplistic notions of traditional life also ignores the well established political-economic critique of the forces partially responsible for the global distribution of resources. Thinking with anthropological and historical depth about what poverty in the contemporary world means in our study populations will provide many key insights about biocultural processes and determinants of population health.

Third, as alluded to above, we need to recognize the salience of health disparities, inequalities and inequities and do our best to determine their causes. The available published literature (or at least my reading of it) indicates that such differences are not inevitable, despite being consequences of the ways humans organize and distribute scare resources. Detailed studies of a variety of health conditions, both infectious and non-communicable, provide powerful evidence that health disadvantage is structured historically, socially and economically. Population health perspectives explicitly claim that fine grained detailed etiologic studies that include measurement of contextual factors are best for providing insights about later intervention research.

I do not suggest that we personally or professionally must advocate reducing health differences, but scientists should be aware of the shift in global ethics that asserts broad human rights ideas about equality in health. At the end of the day and our research endeavors, it seems especially important to evaluate our human biology and biocultural anthropology scientific questions about health in terms of their additional ability to directly address health inequalities. Given the long-term involvement of most anthropologists with specific human populations and the development of informed humanistic attitudes about our study populations, we have opportunities to combine our scholarly evidence with the objective of population health to reduce health inequities.

Absorbing the influences of population health research should be easy for biological anthropologists and human biologists. Human variation remains a key concept for us, and is often a way we distinguish ourselves from other biomedical, public health and social scientists. But including population health ideas will require that we embrace greater concern for sources of variation within our study populations and go beyond comparative statements and analyses about differences between populations. Recent interest in human biology about life history perspectives from evolutionary and developmental biology, and lifecycle perspectives from psychology and sociology are also very compatible with ideas of multi-level causality in population health. We can make a signal contribution to population health by elaborating on both biological and biocultural lifecycle influences, for example in the area of developmental origins of adult diseases.

The focus of population health on the effect of levels of exposure beyond the individual such as family, household, neighborhood, region, and spatially heterogeneous ecological factors is also not strange to us. It may require more explicit interdisciplinary collaborations, care in sample selection and, often, much larger sample sizes along with dissemination and training in multi-level statistical methods. Further exposure to concepts and methods of causal inference are needed so that we can identify potential biases due to omitted variables in our models. In addition, we may need to adopt some of the technical measures of population health developed by Murray and colleagues (1996, 2002), along with an awareness of critiques of these concepts and methods. Their focus on functional health measures, and their inverse, i.e., measures of disability, goes beyond the standard biomedical population health measures such as mortality and morbidity statistics. We also have a scientific obligation to improve such population health measures of function and disability for our study populations given the health economic history of those measures, which may miss ethnographic realities of functional status, health and disease.

Finally, what are the implications for adaptive and evolutionary explanations of a population health perspective with its link to intervention research to reduce health inequalities? Am I suggesting that human adaptation and adaptability research is now passé in the global intellectual and scientific arena? Several papers and volumes have addressed this issue and provide clear answers that we can and should use adaptive thinking as we pursue human biology and health research (Goodman and Leatherman 1998; Huss-Ashmore 2000; Stinson et al 2000; Kuzawa 2005; Keighley et al 2007). Human biology can contribute to population health by providing critical thinking and rigorous tests about long-term evolutionary, adaptive and historical influences on health variations. No matter how well specified the models of health, causal inferences must include the influence of ultimate factors as well as proximate factors. Similarly, our focus on specific study populations, often for many years, provides opportunities to measure and understand deeper context using qualitative methods. This will be necessary for etiologic and applied studies.

In conclusion, I hope that readers of, and contributors to, our journal consider the advantages to their research, and our field, of integrating population health ideas. We look forward to your manuscripts on such topics as we continue to try to make Annals of Human Biology an important outlet for the best interdisciplinary human biology and health research.