The Mismeasure of Man | Study Guide

Stephen Jay Gould

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The Mismeasure of Man | Chapter 2 : American Polygeny and Craniometry Before Darwin: Blacks and Indians as Separate, Inferior Species | Summary



A Shared Context of Culture

Did the science of craniometry add valid data to support racial ranking or was the interpretation of data influenced by prior assumptions? Gould says everyone just assumed in the 18th and 19th centuries that white people were superior to Native Americans and black people. President Thomas Jefferson thought that African Americans were intellectual inferiors. President Abraham Lincoln was proud of the performance of black Union soldiers, but he still maintained that there were physically based differences between whites and African Americans that meant they could never live side by side in full equality. Shared cultural attitudes such as these, not objective data, were the cause of scientists' belief in racial ranking, Gould says. This was true even of liberals like Darwin, who thought the Khoikhoi, a group of people native to southwestern Africa referred to in Darwin's time as the Hottentots, were an intermediate evolutionary form not fully human.

Preevolutionary Styles of Scientific Racism: Monogenism and Polygenism

Even before Darwin, scientists had attempted to prove that the various races of humans were different and could be ranked from high to low. There were two basic views on this subject. One was called monogenism. In this Bible-based system, God was believed to have created a single race of people with Adam and Eve. Since then, however, the various races had all "degenerated" in response to climate: whites least, blacks most. The second view was called polygenism. It claimed that the various races were actually different species of humanity. Whereas many monogenists believed that black people could improve themselves through a change of climate or personal effort, most polygenists believed that blacks could never escape the limits of their birth.

On what did they base these claims? The French anatomist Etienne Serres, who was a monogenist, developed a theory called recapitulation. This taught that black adults were like white children and "Mongolian," or Asian, adults were like white adolescents. This theory was based on the distance from penis to navel, of all things, which is highest in whites, lowest in blacks, and somewhere in the middle for Asians. But many polygenists relied mainly on their belief that whites were simply more physically beautiful than other races.

Louis Agassiz—America's Theorist of Polygeny

Polygeny had its roots in the United States. Europeans referred to it as the "American school" of anthropology, or the study of man. Gould states that one of the primary reasons for American prominence in the theory of polygeny was the existence of legalized slavery in the United States at that time. A system that says that nonwhite races are born inferior and can never rise above that makes it easier to justify the treatment of people as subhuman property.

The leading figure in American polygeny was the Swiss immigrant Louis Agassiz, who taught at Harvard University and came to believe that races were separate species after contact with black people in America. Gould found the original copy of a personal letter written by Agassiz with passages that have never before been translated. These passages reveal a pronounced aversion to black people. Agassiz was repelled by their physical appearance, talking about one free black servant's "hideous hand." He wrote, "It is impossible for me to reprocess the feeling that they are not of the same blood as us."

Still, Agassiz's views on polygeny arose from his style of doing science. When studying any animal, he saw separate species where other scientists simply saw normal variation between individual creatures. He also believed that species arose in one geographical area and rarely migrated away. So without any hard data to support his views, he nonetheless claimed that the Bible spoke only about the creation of the white race. The other races were created separately in other parts of the world. He then claimed that scientists were "obligated" to rank the races due to their physical and behavioral differences. Blacks were at the bottom, as evidenced, Agassiz said, by the fact that no great civilization existed in sub-Saharan Africa. After the Civil War, Agassiz said freed African Americans should be treated equally before the law but not in education or society. He was especially upset about the idea of interracial marriage. He said this would lead to the decline of democracy and social order. Agassiz proposed that separate "Negro states" be created in the hot, humid South while the Northern states remained white.

Samuel George Morton—Empiricist of Polygeny

Agassiz abandoned his own scientific training in order to develop his polygenist views, but American scientist and physician Samuel George Morton tried to use science to support his beliefs. Morton assembled data about the size of skulls that he believed proved the concept of separate and inferior races. He collected 1,000 human skulls between the 1820s and his death in 1851.

Morton theorized that by measuring the skulls of various races, he could prove brain size differed between races—and thus intelligence did as well. He published three books on his results that were considered incontrovertible hard data on the intelligence of human races. In charts and illustrations from Morton's books, Gould shows the results. There were five races: Whites, or Caucasians, had the largest skulls, and black people, or Ethiopians, had the smallest. Asians, or Mongolians, came second; Malays, or people from Polynesia and Oceania, came third; and Native Americans came fourth.

Gould spent several weeks subjecting Morton's raw measurements to a second analysis. He believes that Morton unconsciously manipulated the data to make it look as if it supported his theory when they do not. Gould also discovered that Morton made fundamental statistical errors in his methods. For example, in concluding that Native American skulls were smaller than those belonging to white people, he included too many smaller Inca skulls and too few larger Iroquois skulls. This falsely made it look as if Native Americans on average had smaller brains. When computing the size of Caucasian skulls, Morton deliberately left out smaller Hindu skulls, though they are Caucasian, too. When Gould recalculated using those Hindu skulls, there was no longer any meaningful difference in size between whites and Native Americans, despite what Morton claimed.

Morton made other errors when measuring white and black skulls from Egyptian tombs. Bigger people have bigger brains, simply due to body size. This doesn't mean that they are necessarily smarter, "any more than elephants should be judged more intelligent than humans," Gould explains. Men are in general larger than women, so male brains are larger as well. Scientists have to adjust for body size when recording brain size, and when they do male and female brains are about the same. Morton did not do this. Morton's conclusion that white skulls were larger than black ones may arise because more of the black skulls he measured were female.

After reanalyzing Morton's data and correcting the errors he made, Gould firmly concludes that Morton's measurements actually show no significant differences in skull size between races. Morton had no idea how his prior beliefs of white superiority had influenced both his measurements and his analysis of them.

The American School and Slavery

American polygenists differed as to whether their views on the separate and unequal status of human races supported slavery or not. Southerners welcomed the works of Agassiz, Morton, and others as a defense of slavery. But since polygeny granted no authority to the Biblical account of the creation of Adam and Eve, religious Southerners were uneasy about using polygeny as support. Instead, they relied on the Bible-based theory of monogeny and the degradation of races after creation.


Gould's analysis of Samuel George Morton's skull measurements aroused significant controversy, especially in the years since the publication of the second revised edition of The Mismeasure of Man. Since Gould's conclusions about Morton are at the heart of the book's central theme about how personal and political beliefs can affect scientific objectivity, it is important to be aware of the debate.

In 2011 a team of anthropologists at the University of Pennsylvania not only reanalyzed Morton's raw data, they also remeasured the skulls themselves. Gould did not take this second step. The team concluded that Gould was wrong to state that Morton had fudged his results. In fact, they claim that Gould shows more bias in his book than did Morton. "These results falsify the claim that Morton physically mismeasured crania based on his a priori biases," they write.

Gould had been dead for nine years at the time of this study, but another scientist responded in his defense. In 2014 evolutionary biologist Michael Weisberg took a further look at Morton's data, Gould's analysis, and the University of Pennsylvania reanalysis. Weisberg concludes that the anthropologists at Penn are the ones in the wrong. Although Gould did make a few errors, he is essentially correct in his charges against Morton in The Mismeasure of Man. "Gould's critique of Morton ought to remain as an illustration of implicit bias in science," Weisberg writes.

But the matter didn't end here. A year later, in 2015, three philosophers examined the debate yet again, and concluded that everyone was wrong. The philosophers criticize the Penn study, disagreeing that the anthropologists there have vindicated Morton. Rather, the philosophers support Gould's conclusions that Morton's figures are misleading. However, they think the real lesson from all this is that Morton's work proves nothing. "We challenge the premise shared by both Gould and Lewis et al. that Morton's confused data can be used to draw any meaningful conclusions," they state.

At this point readers may be tempted to agree with the philosophers and give up on science in general. However, all this controversy can actually be seen as another illustration of the very point Gould makes in The Mismeasure of Man. Over and over again Gould hammers home how difficult it is for scientists to prevent their preexisting beliefs from affecting their interpretation of data. In a footnote at the end of the chapter, Gould himself admits an error he made on this topic in an academic journal. "I never saw the inconsistency," he writes, because the error "fit my hopes." This is precisely why Gould wrote the book: to show how alert we must all be in order to determine what the facts really are.

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