The Biology of the Many and the Health of the Individual

Abstract

Although Human Biology takes a scientific approach to the study of human beings, many of those who call themselves Human Biologists have traditionally been found working, directly or indirectly, in health-related fields. The Human Biologist is, at best, a dispassionate scientist whereas the ideal of those in the healthcare professions is to actively contribute to the well-being of individuals in need. Thus, each takes a different practical and philosophical stance in relation to their shared object of interest – humankind.

With the advent of evolutionary (Darwinian) medicine, there is now greater potential for an even closer conceptual relationship between Human Biology and the healthcare professions. As a result, certain branches of Human Biology are likely to become even more closely associated with trying to understand disease as a human biological phenomenon. This brings the two very different outlooks on humankind together into sharp contrast.

While Human Biology is a primarily population-based discipline, healthcare science deals with the phenomena of disease and health as experienced by the individual. An even closer alliance between the two disciplines means that a new way of understanding the individual - a new model of the human as an individual which accounts for disease and health as physical phenomena - may be needed.

Instead of taking a reductionist stance which deconstructs the individual, a means of reconstructing and understanding the individual as a single biological entity may need to be developed more fully.

This poster presentation explores different aspects of what this might entail.

Introduction

Although human biology takes a scientific approach to the study of human beings, many of those who have contributed much to the subject have been medically qualified or working, directly or indirectly, in health-related fields. Important work, from a human biologist's point of view, in growth, nutrition and genetics, for example, has come from such a background¹. In future, even closer links between the two fields may become evident as the influence of evolutionary medicine spreads more widely. However, the conceptual relationship between human biology and medicine is not a simple one; notable differences exist between the two. Although this has the potential to prove problematic, there is also scope for this to prove beneficial for human biology.

Human Biology vs Medicine

The human biologist is, ideally, a dispassionate scientist – an anthropologist in the widest sense of the word – who takes pains to suspend humanitarian judgement in the pursuit of knowledge and understanding about the human species. Those in medicine, however, actively seek to intervene in the lives of those they encounter in order to alleviate suffering and enhance the well-being of those in need.

While human biology is a science closely associated with variations on the theme of the 'normal' human being, medicine is often described as an art and is seen as the profession most closely associated with illness and disease – which are frequently interpreted as deviations from 'normality'.

The Group and the Individual

The activities of epidemiologists and those advocating 'evidence-based medicine' notwithstanding, medicine also deals primarily with individuals. Although guided by certain commonalities of pathophysiological reaction, each clinical case is essentially unique. Human biologists, on the other hand, have focused primarily on groups of people rather than on individuals and, in so doing, have characterised the range of variation present therein.

Indeed, this is, perhaps, one of human biology's particular strengths and greatest contributions. As a discipline, human biology has been able to view human beings in a more complete and rounded way; more so than any other human or biological science. Human biologists have been able to present the many faces of humankind simultaneously. They have been able to view human beings in their wider social, cultural and environmental contexts; they have been able to accommodate the inner workings of the mind as well as the body and all this they have been able to do against the backdrop of an evolutionary context.

However, human biology has never focused on individuals per se. Rather like biology in general, human biology has tended to deal with populations and their statistical characteristics. Here, not only does one think in group or population terms, one sometimes thinks simply in terms of gene pools and gene frequencies. If the picture painted by human biologists can be described as holistic in any way, it is not a holism in the sense of seeing the individual as a whole but in the sense of seeing a particular species in a broad context.

Thus, human biology and medicine have a quite different practical and philosophical stance in relation to their primary object of interest.

Evolutionary Medicine

With the advent of evolutionary medicine,^2,3,5,6 there is now potential for an even closer relationship between human biology and medicine. While the intention of evolutionary medicine was originally to contribute to the treatment of patients by understanding their ailments in an evolutionary context, the medical profession has been relatively slow in the uptake of such ideas. Instead, it has been academic departments with an interest in human biology which have risen to the challenge posed by the issues that evolutionary medicine has raised.

It is evident that now the objects of medicine are increasingly becoming the objects of human biological interest. The expression of physical conditions that have traditionally been solely of medical interest are now of human biological interest as well and quite different explanations and interpretations for well-known medical conditions are being offered.

How to take Evolutionary Medicine

Evolutionary medicine straddles population-based (evolutionary) biology and individually-focused clinical medicine. How then does one apply the ideas of one to the other; in particular, how does one apply the population-derived findings of evolutionary medicine to individuals? These are perennial problems which correspondents (professional and lay) have raised a number of times in various guises upon visiting the author's website.

It would be quite wrong to suggest that all of the suggestions from evolutionary medicine apply equally to all individuals. To take a somewhat graphic example, just because certain autoimmune conditions, such as Crohn's disease, can be alleviated by helminthic therapy⁴, it does not mean that everybody should be given a dose of worms in case their immune systems acted against them. The variability of the human species – as clearly recognised by human biologists – means that we should expect that some may and some may not benefit from such a treatment. This has to be assessed clinically. However, some correspondents do not seem to appreciate this; they seem to assume that the ideas found in evolutionary medicine should be applicable to all simply because of our common ancestry. A wholesale return to a Neolithic, or hunter-gatherer, way of life may be inconceivable but neither is it prescribed. What is suggested is that the suffering of some individuals in the modern world may be remedied by trying a treatment suggested by an evolutionary explanation for the ailment. Each case must be considered on an individual basis.

(Re-)Considering the Individual

By becoming increasingly interested in people's ailments, some human biologists are becoming increasingly interested in what are, in effect, unique events. As a result, a human biology of the individual as an entity in its own right, having been largely missing from human biology so far, may now warrant inclusion. However, for this to be successful, a new way of understanding the individual and a new model of human beings as individuals which accounts for disease and health as physical phenomena may be needed. This is more easily said than done but some ideas may be considered.

The Multifactorial Individual

In modern clinical settings, there is a move towards 'evidence-based medicine'. This takes data for different physiological parameters, drawn from large groups, and uses those data to determine whether measured values for the same parameters in a given individual are clinically acceptable.

Each of an individual's different physiological parameters can be considered as being a point on a distribution (as derived from the group). Figure 1 shows three different measured parameters (1-3) with their putative normal distributions. Marked on the horizontal axes are the specific values for each parameter which individuals 'A' and 'B' exhibit. Each individual can, in effect, be envisaged as displaying a unique set of values for a given set of parameters.

When there are three variables, these values could be plotted in three-dimensional space. However, three variables are too few to give an adequate representation of an individual and while, mathematically, it is possible to go to n-dimensional space (where n is any number), it is very hard to envisage such dimensions and, therefore, individuals in this way.

The Individual as a Pattern Profile

For a given set of parameters, if they are represented in a consistent order, it may be possible to consider the pattern profile of that set of parameters as set out in Figure 2. (Here only three are represented – the same as in Figure 1 – but any number is again possible.)

The pattern profile approach is easier to envisage and goodness-of-fit statistics comparing different patterns can also be applied. However, there are still shortcomings. Individuals are more than just a set of variables or the profile that that set of variables generates. There are many interactions and inter-relationships between variables; one should not, as is often the case, consider all variables as inherently autonomous. Rather, one might envisage a web of interactions taking place.

If each human being can be envisaged in this individualised way as a web of interactions, what different types of web are there to be found within the human species? How are these webs related to environment? How are they inherited, modified, maintained etc?

Conclusion

Here, one is not suggesting a 'new' human biology. Rather, scope exists for an extension of ideas from the traditional population-based thinking to individual-based thinking. This seems to be a natural progression given the former association between human biology and medicine and the more recent advent of evolutionary medicine.

Instead of merely taking the usual population approach – of determining means, frequencies etc. – an extended human biology would seek to understand the life of the individual. This would still be 'human biology'. However, the use of the word 'human' would be more encompassing, being used in the singular as well as the plural sense. After all, without the individual – or series of individuals – there can be no population; and while populations and groups come in quite different sizes, individuals are always singular.

References

¹ Harrison, G.A., Tanner, J.M., Pilbeam, D.R., & Baker, P.T. (1988). Human Biology: An introduction to human evolution, variation, growth and adaptability. Oxford: Oxford University Press.

² Nesse, R., & Williams, G. (1995). Evolution and Healing: The new science of Darwinian medicine. London: Weidenfeld and Nicolson.

³ Stearns, S. (Ed.). (1999). Evolution in Health and Disease. Oxford: Oxford University Press.

⁴ Summers, R.W., Elliott, D.E., Urban, J.F., Thompson, R., & Weinstock, J.V. (2005). Trichuris suis therapy in Crohn's disease. Gut 54 (1): 87–90.

⁵ Trevathan, W., Smith, E., & McKenna, J. (Eds.). (1999). Evolutionary Medicine. New York: Oxford University Press.

⁶ Trevathan, W., Smith, E., & McKenna, J. (Eds.). (2008). Evolutionary Medicine and Health: New perspectives. New York: Oxford University Press.