Chapter 3 – Measuring Heads

Paul Broca and the Heyday of Craniology

The Allure of Numbers

The debate between monogeny and polygeny ended with broad acceptance of Darwin’s theory of evolution by the scientific community after 1859; however, the theory of evolution did not weaken arguments for racism. In fact, monogenists found new support for their racist arguments in the growing use of numbers– these numbers added an aura of unassailable scientific fact to racist claims. One example of a scientist who used numbers to confirm his existing racist biases was French neurologist Paul Broca.


Maters of Craniometry: Paul Broca and His School

In addition to being a neurologist, Paul Broca conducted research in the field of craniometry, improving upon the studies of skull size Morton had done. After conducting these studies, Broca became confident his craniometric data supported the conclusion that white people were intellectually superior to black people–as the cliche goes, “numbers do not lie”.

Gould acknowledges the great care Broca took in collecting his data, and believes the data is quite reliable. However, after reviewing Broca’s data, Gould concludes that much like Morton, Broca put his culturally biased assumptions first–Broca was selective in what he measured and he “unconsciously manipulated” the data afterwards to fit his pre-existing views. When his data did not confirm his belief that whites were superior, Broca changed the guidelines by which he interpreted his data. Even more important, Broca failed to understand that variation between individuals of any species is part of nature; it is not only expected, but predicted by evolutionary biology. And because variation between individuals of any species is natural and normal, it is not a sign of some underlying rank or hierarchy of the various races.



By the turn of the 20th century, the craniometry practices of Paul Broca and other scientists fell out of favor. Scientists began favoring the use of intelligence tests as a means of assessing superiority; results of these intelligence test studies discredited the results of Broca and other scientists. This shift in use of craniometry to use of intelligence tests occurred partially due to the perceived accuracy of mental intelligence testing, and partially due to the presence of new data that failed to support the conclusions of Broca and his followers.