Tiedemann may have chosen his professors for other reasons, but he studied with the most prominent scholars of both persuasions—with the leading egalitarians Blumenbach and Gall (who used phrenology to advocate the material basis of consciousness, and who favored multiple organs of intelligence, expressed in bumps and other features of cranial architecture, largely because each person would then excel in some specific faculty, while no measure could then rank people or groups in a linear order of “general” worth); and with such eminent supporters of racial ranking as Cuvier, and the medical anatomist S. T. Soemmerring, who landed Tiedemann his first job in 1807. (Interestingly, in Tiedemann’s 1836 article on race, the focus of this essay, he quotes both Soemmerring and Cuvier in a strong critique on the opening page, but then praises both Gall and Blumenbach later. Tiedemann also dedicated his 1816 book on the comparative anatomy and embryology of brains, the second document discussed in this essay, to Blumenbach. Obviously, Tiedemann remembered the lessons of his youth—and then developed his own critiques and preferences. What more could a teacher desire?
Tiedemann’s career began on a fast track, with a textbook on zoology and anatomical dissertations on fish hearts (1809), large reptiles (1811 and 1817), and the lymphatic and respiratory organs of birds. He did not neglect invertebrates, either, winning a prize in 1816 from the Académie des Sciences in Paris for a treatise on the anatomy of echinoderms. He then turned his attention to the first of two major projects in his career—a remarkable study, published in 1816, on the embryology of the human brain compared with the anatomy of adult brains throughout the Vertebrata.
When Tiedemann took up his position as professor in Heidelberg, his interests switched to physiology—hence the nature of Owen’s accolade, used as the title of this essay—largely because he met the remarkable young chemist Leopold Gmelin, and the two men recognized that a combination of anatomical and chemical expertise could resolve some outstanding issues in the mechanics and functioning of human organs. Thus, in the second major project of his career, Tiedemann collaborated with Gmelin on a series of remarkable discoveries about human digestion—recognizing, for example, that the intestines and other organs participate in the process, not only the stomach (as previously believed); that digestion involves chemical transformation (the conversion of starch into glucose, for example), not merely dissolution; and that hydrochloric acid works as a powerful agent of digestion in the stomach.
Then, in 1836, Tiedemann published a stunning article in English in the Philosophical Transactions of the Royal Society of London, Britain’s most prestigious scientific journal (then and now): “On the Brain of the Negro, compared with that of the European and the Orang-Outang” (pages 497–527). Why such a shift in focus of research, and why such a foray into a language not his own and never before used to express his research? I do not know the full answer to this intriguing question (for biographical materials on Tiedemann are, to say the least, sparse). But a consideration of his life and work, combined with an exegesis of his two leading publications, provides a satisfactory beginning.
Tiedemann’s unusual paper of 1836 states the egalitarian argument pure and simple—with no ifs, ands, or buts about inferior culture or suboptimal beauty. He does follow Blumenbach in accepting European definitions as universal aesthetic norms—a claim that can only strike our modern sensibilities as almost naïvely humorous. But, unlike Blumenbach, he then holds that Africans measure up to Caucasian standards of beauty. Of Africans living freely in the continent’s interior, untouched by slavery, Tiedemann writes:
Their skin is not so black as that of the Negroes on the coast of Guinea, and their black hair is not so woolly, but long, soft, and silky. They have neither flat noses, thick lips, nor prominent cheekbones; sloping contracted forehead, nor a skull compressed from both sides, which most naturalists consider as the universal characteristics of a Negro. Most of them have well-formed skulls, long faces, handsome, even Roman or aquiline noses, thin lips, and agreeable features. The Negresses of these nations are as finely formed as the men, and are, with the exception of their color, as handsome as European women.
(This remarkable statement illustrates the vintage of conventional prejudice, as the nineteenth century’s firmest egalitarian scientist never doubts the “obviously” greater beauty of light skin, straight hair, thin lips, and “Roman or aquiline noses”!)
Tiedemann then argues that the false impression of African ugliness arose from limited studies of people suppressed by slavery and living at the coast:
The mistaken notion of these naturalists arose from [study]. . . of a few skulls of Negroes living on the coasts, who, according to credible travellers, are the lowest and most demoralized of all the Negro tribes; the miserable remains of an enslaved people, bodily and spiritually lowered and degraded by slavery and ill treatment.
The technical argument of Tiedemann’s paper follows a clear and simple logic to an equally firm conclusion—an exemplar of scientific reasoning, so long as the data hold up to scrutiny and withstand the light of new findings. Tiedemann develops two sources of information to reach the same conclusion. He first uses his anatomical expertise to search for distinctions among the brains of Caucasians (both males and females), black Africans, and orangutans. And he finds no structural differences among humans of different races and sexes. He begins with the cerebrum, the traditional “seat” of intelligence, and concludes: “In the internal structure of the brain of the Negro I did not observe any difference between it and that of the European.” He then studies any other part used by scientific colleagues to assert differences in rank—particularly to test the claim that blacks have thicker nerves than whites. Again, he finds no distinction: “Hence there is no remarkable difference between the medulla oblongata and spinal cord of the Negro and that of the European, except the difference arising from the different size of the body.”
Tiedemann then moves on to a second and clinching argument based on size, for some colleagues had accepted the conclusion of no structural difference, but had then defended racial ranking on supposed grounds of “more is better,” arguing that Caucasians possessed the largest brains among human races, and African blacks the smallest. Tiedemann understood the complexity of this subject, and the consequent need for statistical analysis. He recognized that weighing a brain or two could not decide the issue because brains grow in correlation with bodies, and larger bodies therefore house bigger brains, quite independently of any hypothetical differences caused by racial inequalities. Tiedemann understood, for example, that small brains of women only reflected their smaller bodies—and that appropriate corrections for size might put women ahead. He therefore writes, controverting the greatest and most ancient authority of all:
Although Aristotle has remarked that the female brain is absolutely smaller than the male, it is nevertheless not relatively smaller compared with the body; for the female body is in general lighter than that of the male. The female brain is for the most part even larger than the male, compared with the size of the body.
Tiedemann also recognized that brain sizes varied greatly among adults of any individual race. Therefore, a prejudiced observer could tout any desired view merely by choosing a single skull to fit his preferences, no matter how unrepresentative such a specimen might be as surrogate for an entire group. Thus, Tiedemann noted, many anthropologists had simply chosen the smallest-brained and biggest-jawed African skull they could find, and then presented a single drawing as “proof” of what every (Caucasian) observer already “knew” in any case! Tiedemann therefore labored to produce the largest compilation of data ever assembled, with all items based entirely on his own measurements for skulls of all races. (He followed the crude, but consistent, method of weighing the skull, filling the cavity with “dry millet-seed,” weighing again, and finally expressing the capacity of the brain case as the weight of the skull filled with seed minus the weight of the empty skull.)
From his extensive tables (38 male African and 101 m
ale Caucasian skulls, for example—see my later comments on his methods and results), Tiedemann concluded that no differences in size of the brain can distinguish human races. In one of the most important conclusions of nineteenth-century anthropology—a statement, based on extensive data, that at least placed a brake upon an otherwise unchallenged consensus in the opposite direction—Tiedemann wrote:
We can also prove, by measuring the cavity of the skull in Negroes and the men of the Caucasian, Mongolian, American, and Malayan races, that the brain of the Negro is as large as that of the European and other nations. . . . Many naturalists have incorrectly asserted that Europeans have larger brains than Negroes.
Finally, Tiedemann closed the logical circle to clinch his argument by invoking the materialist belief of his teacher, F. J. Gall: brain stuff engenders thought, and brain size must therefore correlate at least roughly with intellectual capacity. If the brains of all races differ in neither size nor anatomy, we cannot assert a biological basis for differences in intellect among groups and must, on the contrary, embrace the opposite hypothesis of equality, unless some valid argument, not based on size or structure, can be advanced (an unlikely prospect for scientific materialists like Tiedemann and Gall). Tiedemann writes:
The brain is undoubtedly the organ of the mind. . . In this organ we think, reason, desire, and will. In short, the brain is the instrument by which all the operations called intellectual are carried on. . An intimate connection between the structure of the brain and the intellectual faculties in the animal kingdom cannot be doubted. As the facts which we have advanced plainly prove that there are no well-marked and essential differences between the brain of the Negro and the European, we must conclude that no innate difference in the intellectual faculties can be admitted to exist between them.
Claims for African inferiority have almost always been based on prejudiced observation of people degraded by the European imposition of slavery:
Very little value can be attached to those researches, when we consider that they have been made for the most part on poor and unfortunate Negroes in the Colonies, who have been torn from their native country and families, and carried into the West Indies, and doomed there to a perpetual slavery and hard labor. . . . The original and good character of the Negro tribes on the Western Coast of Africa has been corrupted and ruined by the horrors of the slave trade, since they have unfortunately become acquainted with Europeans.
Tiedemann’s Data
Sample
Number of Skulls
Smallest
Largest
Average
weight in ounces
Caucasian (all)
101
28
57
40.08
European Caucasian
77
33
57
41.34
Asian Caucasian
24
28
42
36.04
Malayan
38
31
49
39.84
American
24
26
59
39.33
Mongolian
18
25
49
38.94
Ethiopian
38
32
54
37.84
I have now done my ordinary duty as an essayist: I have told the forgotten story of the admirable Tiedemann with sufficient detail, and in his own words, to render the flavor of his concerns, the compelling logic of his argument, and the careful documentation of his empirical research. But, curiously, rather than feeling satisfaction for a job adequately done, I am left with a feeling of paradox based on a puzzle that I cannot fully resolve, but that raises an interesting issue in the social and intellectual practice of science—thus giving this essay a fighting chance to move beyond the conventional.
The paradox arises from internal evidence of Tiedemann’s strong predisposition toward belief in the equality of races. I should state explicitly that I refer, in stating this claim, not to the logic and data so well presented in his published work (as discussed above), but to evidence based on idiosyncrasies of presentation and gaps in stated arguments, that Tiedemann undertook the research for his 1836 article with his mind already set (or at least strongly inclined) to a verdict of equality. Such preferences—especially for judgments generally regarded as so morally honorable—might not be deemed surprising, except that the ethos of science, both then and now, discourages such a priori convictions as barriers to objectivity. An old proverb teaches that “to err is human.” To have strong preferences before a study may be equally human—but scientists are supposed to disregard such biases if their existence be recognized, or at least to remain so unconscious of their sway that a heartfelt and genuine belief in objectivity persists in the face of contrary practice.
Tiedemann’s preferences for racial equality do not arise from either of the ordinary sources for such a predisposition. First, I could find no evidence that Tiedemann’s political or social beliefs inclined him in a “liberal” or “radical” direction toward an uncommon belief of egalitarianism. Tiedemann grew up in an intellectually elite and culturally conservative family. He particularly valued stable government, and he strongly opposed popular uprisings. Three of his sons served as army officers, and his eldest was executed under martial law imposed by a temporarily successful revolt (while his two other military sons fled to exile) during the revolutions of 1848. When peace and conventional order returned, the discouraged Tiedemann retired from the university, and published little more (largely because his eyesight had become so poor) beyond a final book (in 1854) titled The History of Tobacco and Other Similar Means of Enjoyment.
Second, some scientists tend, by temperament, to embrace boldly hypothetical pronouncement, and to publish exciting ideas before adequate documentation can affirm their veracity. But Tiedemann built a well-earned reputation for the exactly opposite behavior of careful and meticulous documentation, combined with extreme caution in expressing beliefs that could not be validated by copious data. The definitive eleventh edition of the Encyclopaedia Britannica (1910–11), in its single short paragraph on Tiedemann, includes this sole assessment of his basic scientific approach: “He maintained the claims of patient and sober anatomical research against the prevalent speculations of the school of Lorenz Oken, whose foremost antagonist he was long reckoned.” (Oken led the oracular movement known as Naturphilosophie. He served as a sort of antihero in my first book, Ontogeny and Phylogeny, published in 1977—so I have a long acquaintance, entirely in Tiedemann’s favor, with his primary adversary.)
I have found, in each of Tiedemann’s two major publications on brains and races, a striking indication—rooted in information that he does not use, or data that he does not present (for surprising or illogical absences often speak more loudly than vociferous assertions)—of his predisposition toward racial equality.
1. Creating the standard argument, and then refraining from the usual interpretation: Tiedemann’s masterpiece of 1816.
By customary criteria of new discovery, copious documentation, and profound theoretical overview, Tiedemann’s 1816 treatise on the embryology of the human brain, as contrasted with adult brains in all vertebrates (fish to mammals), has always been judged as his masterpiece (I quote from my copy of the French translation of 1823). As a central question in pre-Darwinian biology, scientists of Tiedemann’s generation yearned to know whether all developmental processes followed a single general law, or if each pursued an independent path. Two processes stood out for evident study: the growth of organs in the embryology of “higher” animals, and the sequence of structural advance (in created order, not by evolutionary descent) in a classification of animals from “lowest” to “highest” along the chain of being.
In rough terms, both sequences seemed to move from small, simple, and homogeneous beginnings to larg
er, more-complex, and more-differentiated endpoints. But how similar might these two sequences be? Could adults of lower animals really be compared with transitory stages in the embryology of higher creatures? If so, then a single law of development might pervade nature to reveal the order and intent of the universe and its creator. This heady prospect drove a substantial amount of biological research during the late eighteenth and early nineteenth centuries. Tiedemann, beguiled by the prospect of discovering such a universal pattern, wrote that the “two routes” to such knowledge “are those of comparative anatomy and the anatomy of the fetus, and these shall become, for us, a veritable thread of Ariadne.” (When Ariadne led Theseus through the labyrinth to the Minotaur, she unwound a thread along the path, so that Theseus could find his way out after his noble deed of bovicide. The “thread of Ariadne” thus became a standard metaphor for a path to the solution of a particularly difficult problem.)
Tiedemann’s densely documented treatise announced a positive outcome for this grand hope of unification: the two sequences of human fetal development and comparative anatomy of brains from fish to mammals coincide perfectly. He wrote in triumph:
I therefore publish here the research that I have done for several years on the brain of the [human] fetus. . I then present an exposition of the comparative anatomy of the structure of the brain in the four classes of vertebrate animals [fish, reptiles, birds, and mammals in his taxonomy]—all in order to prove that the formation of this organ in the [human] fetus, followed from month to month during its development, passes through the major stages of organization reached by the [vertebrate] animals in their complexity. We therefore cannot doubt that nature follows a uniform plan in the creation and development of the brain in both the human fetus and the sequence of vertebrate animals.