Health in Action Worldmapper: The Human Anatomy of a Small Planet Danny Dorling The Challenge: Understanding Global Inequalities “Throughout the world, people who are vulnerable and socially disadvantaged have less access to health resources, get sicker, and die earlier than people in more privileged social positions. Health equity gaps are growing today, despite unprecedented global wealth and technological progress” [1]. You can say it [1], you can prove it [2], you can tabulate it [3], but it is only when you show it that it hits home [4]. There is a long history of using illustrations to help spread new medical scientific ideas. Anatomical imagery, for example, is at least 500 years old [5]. That imagery allowed us to look inside human beings and, among much else, showed us just how much of the brain was dedicated to visual understanding. We now know that good health relies as much on the anatomy of society as on the anatomy of our bodies [6]. And we are just beginning to learn that an unequal human world is also more likely to be a sick world. How, though, can we better understand the distribution of health resources around the world, and of where most people are sick and die early as compared to people in more privileged positions? How can we fathom the extent to which health equity gaps are growing despite unprecedented global wealth and technological progress? Drawing images is one way to engage more of our imagination to help understand the extent and arrangement of world inequalities in health. Medical Mapping The science of the make up of world human anatomy—cartography—has a similar history to that of anatomical drawing. Gerardus Mercator’s wall maps of 1569 were produced just 14 years after the second edition of Andreas Vesalius’ humani corporis fabrica. And just as Vesalius’ images helped guide the scalpel through fl esh, Mercator’s maps helped guide ships across the oceans. But these products of the enlightenment were not just simple guides. The images they produced helped change the way we thought about the world. In the long run they helped us learn to be less superstitious, but also presented a very mechanical, inhuman image of both person and planet. Mercator’s projection is the one you still see when the weather is described on television and it, or a near equivalent, is the one used in most medical mapping (for an example depicting the world geography of malaria see [7]). The Mercator projection is a useful projection to carry with you if you wish to sail around the planet. It is not, however, that useful for showing how a disease such as malaria is spread amongst the population. To show such spread, a world population cartogram is a far better base map—an example is shown in [8]. The Mercator projection is the worst of all the well known global map projections to use to depict disease distributions because it stretches the earth’s surface to the most extreme of extents and hence introduces the greatest visual bias. On a Mercator projection area is drawn in ever expanding proportion to how near territory is to the poles. Thus, on such a projection, India appears much smaller than Greenland, whereas India is in land area alone over seven times larger than Greenland. The world distribution of malaria shown on a conventional map [7] gives the impression that the global distribution of clinical episodes of Plasmodium falciparum malaria is confined to a much smaller proportion on an equal land area map it would still give the impression that malaria was only confined to a small portion of the world’s land. Malaria is, however, a disease of people, not of land. A better base-map (had it been available) upon which the distribution could have been drawn would have been the population cartogram [8]. My aim here is not to specifically criticise the depiction of the distribution of malaria on a conventional map. Such depiction is simply representative of what is accepted as normal in much medical mapping, even by authors with access to software that allows them to produce non-unique cartograms [9]. The Solution: Creating Maps of Inequalities The new world population cartogram published in Nature in 2006 [8] was produced by Mark Newman [10] and shows the world with land area drawn in proportion to the population. Unlike previous cartograms, this cartogram is produced by software which approximates to the best unique world cartogram (that which distorts the least on the surface of the sphere whilst still scaling areas correctly). One criticism of older algorithms has been that they produce an “area correct” but somewhat arbitrary solution with Funding: The funding for the Worldmapper project came from the award of a prize from the Leverhulme Trust. The trust played no role in the submission or preparation of this article. Competing Interests: The author has declared that no competing interests exist. Citation: Dorling D (2007) Worldmapper: The human anatomy of a small planet. PLoS Med 4(1): e1. doi:10.1371/journal.pmed.0040001 Copyright: © 2007 Danny Dorling. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. of the earth’s surface than is actually The Health in Action section is a forum for individuals the case. Danny Dorling is Professor of Human Geography or organizations to highlight their innovative However, even if the distribution of a at the Department of Geography, University of approaches to a particular health problem. Sheffi eld, Sheffield, United Kingdom. E-mail: Daniel. disease such as malaria had been drawn PLoS Medicine | www.plosmedicine.org 0013 January 2007 | Volume 4 | Issue 1 | e1doi:10.1371/journal.pmed.0040001.g001 Figure 1. Public Health Spending: Worldmapper Poster 213 The figure shows a cartogram in which territories are drawn with their area in proportion to the values being mapped. Territories are shaded identically on all cartograms here to aid comparison with the world cartograms shown in Figures 2 to 6 which employ identical shading. For detail on shading see http://www.worldmapper.org. Source of data used to create map: United Nations Development Programme, Human Development Report 2004. doi:10.1371/journal.pmed.0040001.g002 Figure 2. Private Health Spending: Worldmapper Poster 214 Source of data used to