Fingerprints, Race, and Population

Ever since the time of its invention in the 19th century, modern fingerprint identification was envisioned as a tool for controlling colonial subjects and immigrant populations. Whether in colonial India, Argentina, or the U.S. West Coast – a site of strong anti-Chinese racism – fingerprint identification seemed to hold the promise of giving the state stronger control over particular groups that were viewed in some way as “untrustworthy,” a racist idea that equated group affiliation with criminality and propensity to lie about one’s identity [1].

Another way that the history of fingerprinting has overlapped with ideas about race, identity, and difference has been in scientific research. Starting in the late 19th century, those with an academic interest in fingerprints have tried to investigate whether certain kinds of fingerprint patterns could be associated with particular “races” (they cannot). Those who carried out this research soon came to realize what a futile endeavor it was. Nonetheless, the search for evidence of “racial” identity and difference in fingerprints would continue in another form: studies of the frequency with which different fingerprint characteristics appear in different racially-defined groups [2].

Before going more deeply into what this kind of research involved and what its flaws were, it is worth briefly considering the relationship between race and science more generally. Today we recognize that race is a “social construction” rather than a natural, scientifically-verifiable fact. To quote the bioethicist Osagie Obasogie, saying that race is socially constructed implies the following propositions:

• the importance placed on the outward physical distinctions that societies traditionally use to draw racial boundaries vary substantially over time and place,

• these physical distinctions do not reflect any inherent meanings, abilities, or disabilities, and

• racial differences in social and health outcomes do not correlate meaningfully with underlying biological or genetic mechanisms [3].

To put this in slightly different terms, “race” – including the selection of physical features viewed as relevant to race – is given meaning by society. Thus, the meaning and boundaries of race, racial identity, and difference are not facts that can be empirically determined by science. In the early 20th century, this was an assumption that many people held – namely, that science could authoritatively explain the differences between “races.”

This assumption motivated decades of research in dermatoglyphics, the scientific study of fingerprints and other ridged skin. As an example, we can examine the following chart, which appeared in Cummins and Midlo’s Fingerprints, Palms and Soles (1943), a text that has played an important role in the history of dermatoglyphics.

Note: This image might not display properly on smaller screens.

Image: Harold Cummins and Charles Midlo. Finger Prints, Palms and Soles: An Introduction to Dermatoglyphics. New York: Dover Publications, 1961, 260. Used with permission. Image courtesy of Dover Publications.

In this chart, we can see that each population is represented by a horizontal bar. The starting and ending points of each bar are determined by the scale lying along the chart’s horizontal axis. To the left of the vertical axis is a scale showing the proportion of arch patterns in a given population and to the right is a scale showing the proportion of whorls. The length of each bar is thus meant to indicate the relative proportions of arches and whorls.

The impression that one gets from this kind of chart is that each “racial” group is itself homogeneous with respect to dermatoglyphic features, but also distinct from every other group. This presentation of data also implies that these differences are not simply real but also quantifiable, an important source of authority in science.

In fact, it is important to apply a critical perspective to these assumptions. For one thing, in presenting a typology of distinct “racial” groups in this way, such studies start out with the assumption that there are racially-significant differences to be found, a form of circular reasoning. Moreover, research studies such as this rarely if ever specify how the particular “racial” groups under study are defined, nor do they explain whether socially, politically, and geographically defined populations (for example, “Formosan Chinese,” “Manchurian Chinese,” and so on) can be taken as proxies for biologically-defined groups. In short, in research such as this, “race” is a concept that tends to represent human genetic diversity in overly simplistic ways.

For more on the construction of race in dermatoglyphics, watch this short lecture. 

Still, despite these issues, researchers would continue to carry out surveys of population-level fingerprint pattern variation throughout the rest of the 20th century, accumulating a large body of data in the process. We can get a sense of the truly global scope of such efforts from the following image, which appeared in a research study by geneticist David C. Rife in 1953.

Note: This image might not display properly on smaller screens.

Image republished with permission of Elsevier Science & Technology Journals, from David C. Rife (1953), “Finger prints as criteria of ethnic relationship.” American Journal of Human Genetics, 5, 4, 389-399; permission conveyed through Copyright Clearance Center, Inc.

In creating this image, Rife synthesized the information that had been collected in numerous studies of fingerprint-pattern variation focusing on populations in the Americas, Europe, Africa, and Asia. The differently shaded areas on the map represent differences in the “index of pattern intensity” – a quantitative measurement indicating the proportion of whorls and loops in a given population. As this image indicates, many such studies had been carried out by the early 1950s and they contributed to a global view of fingerprint pattern variation.

The question of how the frequencies of particular fingerprint characteristics might differ across populations remains a subject of research today, albeit in ways that are very different from the dermatoglyphics research of the early 20th century. Whereas earlier researchers tended to study fingerprints in order to speak to more general questions about “racial” identity and difference that arose within physical anthropology, today’s researchers are focused on using such data to improve latent fingerprint evidence [4]. The goal is not simply to identify similarities and differences in the fingerprint patterning of different racially-defined groups, but rather to develop an understanding of how often particular fingerprint characteristics appear in different populations in order to improve forensic identification practice.

Given its focus on latent print evidence, it should not be surprising that today’s research focuses on fingerprint minutiae, characteristics that play an important role in forensic identification. It is believed that gaining a better understanding of the frequency and distribution of minutiae types within a given population will lead to improvements in the process through which latent prints are identified. In the words of the authors of one such study,

When tackling any calculation of probable identity, we feel it is necessary to take into account, and so know, the frequency with which different types of minutiae occur within the different human populations, as well as their relation to gender, finger, pattern type and the area of the finger. This would permit the use of more specific probability models in accordance with the different known aspects in each identity test [5].

In this instance, understanding how frequently ridge endings, bifurcations, and other ridge characteristics appear in the “Spanish population” (the focus of the authors’ research) is useful because it might make it possible to “quantify the degree of ‘rareness’ of the points used when fingerprints of this finger are evaluated.” Thus, carrying out this kind of research could help fingerprint examiners to determine the relative evidentiary value of different fingerprint characteristics while placing fingerprint identification work on a firmer body of scientific data.

Studies that focus on population-level variation in fingerprint minutiae such as this one tend to define the populations under study in different ways. Categories such as “race” and “ethnicity” are used in some studies, while “population” and “ancestry” are used in others [6]. The long history of anthropological research in dermatoglyphics, discussed above, should alert us to some of the methodological issues that are involved in conceptualizing population-level variation in these ways. For example, categories such as “white” and “black” – to draw on those used in a recent study of fingerprint minutiae – are socially constructed: they derive from practices of categorization that are imposed by society as well as an individual’s “self-identification” [7]. As Troy Duster has noted, it is a mistake to “reify” such categories as biological facts: one can easily forget just how phenotypically arbitrary (and socially determined) the most common ethnic and racial categorizations are [8].

Sources

[1] Simon A. Cole. Suspect Identities: A History of Fingerprinting and Criminal Identification. Cambridge, MA: Harvard Univ. Press, 2002, 63-65, 121-127, 131-133. For more on the historical relationship between fingerprinting, race, and racism, see Simon A. Cole, S.A. “Twins, Twain, Galton, and Gilman: Fingerprinting, Individualization, Brotherhood, and Race in Pudd’nhead Wilson.” Configurations, 15, 3 (2007): 227-265.

[2] Daniel Asen. “‘Dermatoglyphics’ and Race after the Second World War: The View from East Asia.” In Global Transformations in the Life Sciences, 1945–1980, edited by Patrick Manning and Mat Savelli, 61-77. University of Pittsburgh Press, 2018.

[3] Osagie Obasogie, Playing the Gene Card? A Report on Race and Human Biotechnology (Oakland, CA: Center for Genetics and Society, 2009), 3. 

[4] Daniel Asen. “Fingerprints and Paternity Testing: A Study of Genetics and Probability in Pre-DNA Forensic Science.” Law, Probability and Risk 18, nos. 2-3 (2019): 194-195.

[5] Esperanza Gutiérrez, Virginia Galera, Jose Manuel Martínez, Concepción Alonso. “Biological variability of the minutiae in the fingerprints of a sample of the Spanish population.” Forensic Science International 172 (2007): 98-105, quote from p. 104.

[6] i.e. Expert Working Group on Human Factors in Latent Print Analysis. Latent Print Examination and Human Factors: Improving the Practice through a Systems Approach. U.S. Department of Commerce, National Institute of Standards and Technology, 2012, 57, 63; Nichole A. Fournier and Ann H. Ross. “Sex, Ancestral, and Pattern Type Variation of Fingerprint Minutiae: A Forensic Perspective on Anthropological Dermatoglyphics.” American Journal of Physical Anthropology 160, no. 4 (2016): 625-632.

[7] Fournier and Ross, “Sex, Ancestral, and Pattern Type Variation of Fingerprint Minutiae.” For a critical discussion of the implied use of “race” in this piece, see Simon A. Cole. “Individual and collective identification in contemporary forensics.” BioSocieties, Online First, published 17 December 2018 (2018): 1–26.

[8] Troy Duster. “Race and Reification in Science.” Science, New Series 307, no. 5712 (2005): 1050-1051.