June 28th was the 194th birthday of Paul Broca, the physician and anthropologist who discovered the area of the brain responsible for our ability to produce spoken language. His discovery marked the first clear link between a region of the brain and a specific function, and it advanced our understanding of both brain structure and language. But Broca’s discovery, like much of the medical and anthropological research of his time, was born in a context of deeply racist ideas.
Huge swaths of anthropology and medical science in the mid-nineteenth century were explicitly racist, and Broca was no exception. Rather than a species with a common origin and variations in physical appearance, Broca and his fellow polygenists believed that human ethnic groups were actually completely distinct species which been created separately in different parts of the world. It’s not hard to imagine the kinds of things European colonial powers justified by viewing other peoples as different – and, almost always, lesser – species, especially since at the time, many anthropologists believed that cultures could be ranked along a continuum from barbaric to civilized – terms which make modern anthropologists cringe.
Broca’s preoccupation with racial classifications drove his interest in anthropometry, the measurement of the human body. Like many of his contemporaries, he espoused the idea that physical features, such as how far forward a person’s upper or lower jaw protruded, the ratio of the brain’s length to its width, or the length of a person’s arms relative to their torso, could predict intelligence. And Broca and his colleages, steeped in European ethnocentrism, always associated intelligence with traits that tended to be more common among European populations.
And that’s how Broca ended up examining brains. The mid-19th century was the heyday of phrenology, a field of study that claimed to be able to draw conclusions about a person’s character, personality, and intelligence based on the shape and features of their skull. A bump in the wrong place might brand you a habitual criminal or reveal an innate tendency to aggression, phrenologists claimed. The foundation of the whole discipline was the idea that certain areas of the brain controlled certain personality traits, as well functions like speech, memory, and motor control.
By the early 1860s the scientific community was starting to debate this set of ideas. At the Society of Anthropology of Paris, a scientific society founded and led by Broca, discussion centered on whether the capacity for language could be traced to a particular piece of the brain. In an effort to settle the debate, Broca paid a visit in 1861 to a patient named Louis Victor Leborgne, who had been nicknamed “Tan” because that was the only word he could clearly pronounce. Leborgne could understand other people’s speech with no trouble, and his mental faculties were intact – he just couldn’t make his mouth form the words he wanted to say.
Leborgne passed away shortly after Broca’s visit, and the surgeon returned to the hospital to perform an autopsy on Leborgne’s brain. He noticed a lesion in the left frontal lobe, and over the next few years he found lesions in the same spot in the brains of 12 other people who shared Lebourgne’s trouble with words. (Most of those brains are now on display at the Pierre and Marie Curie University in Paris.) Today, we know that that area of the brain plays an important role in the production of language, and it bears Broca’s name. The inability to form words which plagued Lebourgne is now called Broca’s Aphasia. (That’s distinct from Wernicke’s Area, a bit further back in the brain on the left temporal lobe. A lesion there produces Wernicke’s Aphasia, in which a person can’t understand language.)
Broca’s discovery marked the first known link between a specific region of the brain and a specific neurological function. Scientists have since discovered many others, and we now have a reasonably good map of which parts of the brain are linked to which functions – although the idea that their shape is linked to personality traits, let alone that the shape of a person’s skull can predict their character, has long since been thoroughly discredited.
The racist underpinnings of much of Broca’s body of work don’t alter the significance of his discovery, but it’s important to place his work into the context of his attitudes and assumptions. It gives us a stark look at how far science has come in just 150 years. And it reminds us that even those who make great discoveries are also capable of embracing some really awful ideas. Broca’s story reminds us that scientists are human, and good science requires evaluating ideas on their own merits.