This dissertation is history of how researchers have trusted biometric technologies to operate objectively but have perpetuated racial bias in the technologies’ design and output. It explores the origins and development of the biometric study of race and skulls during the rise and hardening of colonialism. A turn to quantification marks this period: researchers increasingly relied on measurements and statistical methods to develop racial classifications of the world’s populations. With a central focus on racial data and the practices that produced the data, the dissertation is a transnational history that follows the data from measurement encounters in colonial spaces, to laboratories in the United States and Europe, to printed form in publications. It transcends disciplinary boundaries and integrates anthropology, anatomy, statistics, and genetics, thus offering a fresh perspective on the history of racial science.

I reveal a methodological crisis around 1900, spurred by a heterogeneous approach to studying race. Measurements and instruments like the skull-measuring caliper were introduced in the 19th century to infuse anthropology with precision. Meanwhile, researchers continued to study skulls through observations with a “trained eye.” By 1900, racial data had piled up without clear taxonomic value, creating a distrust in quantification and confusion about the direction of racial research. In the first half of the 20th century, statisticians like Karl Pearson began transforming anthropology with new biometric methods to make racial research more “scientific.” The dissertation argues that biometricians quantified and automated racial research: they made new use of the caliper by combining it with disembodied statistical formulas. Automation entailed a critique of the anthropologist’s subjective “trained eye” expertise and a reduction of human intervention in favor of objectivity. The biometricians, however, never challenged racial research itself and continued to reproduce old racial biases in their new methods and theories. Even in challenging Nazi race theories, they never questioned the existence of race. The dissertation thus uncovers how biometric practices were considered objective and reproduced racial prejudices.