Genus and Spleniums — The Mismeasure of Man

It was the end of the fall semester of U1, and I was sitting in the last lecture of LING 390 (Neuroscience of Language), one of my favourite classes at McGill University to date. Taught by an excellent researcher whose name I’ll shorten to Prof. G, the class focused on the brain mechanisms underlying language, as its name implies, and the various physical measures of the brain used over the years to ascertain its inner workings, from phrenology to fMRI.

fMRI image source: Life by Experimentation

In this last lecture, Prof. G had chosen to expound on one of the key messages that he hoped we would take away, and that was one of ethics and bias in scientific measurement. He emphasized that this was especially important with regards to the study of the brain, as this can often be so quickly and wrongfully seen as tied with human intelligence and then with worth. Illustrating some of the unfortunately many sickening examples of the use of “science” to support racist beliefs, Prof. G finished by recommending, as required reading for anyone in a field tied to psychology, The Mismeasure of Man, by Stephen Jay Gould. Whether one agrees with everything he writes or not, Gould paints an excellent picture of how measurement can go awry and of times when tests have done a less than stellar job of actually measuring what they are supposed to measure.

I wanted to share with you a brief summary of one such study given as an example in Chapter 3 of the book:

The following graph was published in a 1906 article by the Virginia physician Robert Bennett Bean that compared the brains of black and white Americans.

Figure 1: The caption reads: “3.1 Bean’s plot of the genu on the y-axis vs. the splenium on the x-axis. White circles are, unsurprisingly, for white brains; black squares for black brains. Whites seem to have a larger genu, hence more up front, and presumably more intelligence.”

Bean’s racist biases are clearly demonstrated when this graph is compared with the one in Figure 2, which maps the data gathered by Franklin P. Mall.

Figure 2: The caption reads: “3.2 Mall’s plot of genu vs. splenium. Mall measured the brains without knowing whether they came from whites or blacks. He found no difference between the races. The line represents Bean’s separation between whites and blacks.”

Mall measured the genus and spleniums of blacks and whites using the same procedure as Bean (he also reused 18 of the brains from Bean’s original sample). However, Mall did not know which brains came from blacks and which from whites until after conducting measurement. His findings revealed no differences in the relative size of genu and splenium, as seen in Figure 2. It appears that Bean’s personal biases likely caused him to subconsciously (or consciously) mis-measure brains in order to confirm the theory that black Americans were less intelligent than white Americans. Mall’s follow-up study clearly discredits Bean’s findings.

Although we now look at this study and likely think how ridiculous this process and conclusion was, how many tests and measures do we take for granted as being indicative of “innate” qualities such as intelligence or personality, that may not actually be as valid as we think they are? And further, what are the potential social outcomes of these assumptions?

Here are the full APA references to Robert B. Bean’s and Franklin P. Mall’s studies, in case you’re curious to see what they actually looked like (trigger warning for racism (and bad science…)):

Bean, R. B. (1906). Some racial peculiarities of the Negro brain. American Journal of Anatomy, 5(4), 353–432.

Mall, F. P. (1909). On several anatomical characters of the human brain, said to vary according to race and sex, with especial reference to the weight of the frontal lobe. American Journal of Anatomy, 9(1), 1–32.

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