BRONN, HEINRICH GEORG

(b. Ziegelhausen bei Heidelberg, Germany, 3 March 1800; d. Heidelberg, 5 July 1862)

paleontology, zoology, morphology, geology, Darwin reception.

Bronn was a great compiler of reference works in zoology and paleontology, but recent scholarship emphasizes that he also broke new conceptual and methodological ground by situating fossil species in geological time, geographic space, and environmental conditions. By considering when, where, and how species lived, quantifying rates and patterns of species turnover and morphological progress, Bronn helped to establish paleontology as a modern scientific discipline at the interface between biology and geology. His reference works and his editorship of an important geological journal also provided practical support for the discipline’s growth.

In the 1840s and 1850s, Bronn’s explanations of pale-ontological change centered on the physical evolution of Earth and the continual adaptation of floras and faunas to prevailing conditions. As the planet’s environments changed and diversified, obsolescent species became extinct, to be replaced by better-adapted and morphologically similar, but more advanced, ones. He left open the question of how the new species arose, sometimes suggesting that divine intervention was needed, and sometimes invoking a hypothetical “creative force,” and focused instead on deriving the laws that any such force would have to obey. The provisional nature of this solution, along with his lifelong attention to adaptation and diversification, made him cautiously receptive to Charles Darwin’s theory of evolution by natural selection, which he introduced to German readers in his own translation, with a critical commentary at the end.

Life, Education, and Career. Bronn was the fifth of seven children of Georg Ernst Bronn, a government forestry official, and Elisabeth Margarethe Bronn. He was raised a Catholic, attended elementary school in Ziegelhausen and gymnasium in Heidelberg, and began attending the University of Heidelberg in 1817. He studied cameralism and natural history, possibly with the intention of pursuing a civil-service career like his father's. This course of study contrasts with the medical training that was more usual for German morphologists, and it allowed Bronn to range more broadly into applied sciences such as forestry, mining, and plant and animal breeding. Bronn’s most influential teacher at Heidelberg was probably the geologist Karl von Leonhard.

In 1821, after completing his habilitation in natural history and Encyclopädie der Staatswissenschaften (general sciences of the state), Bronn began to teach at Heidelberg at the rank of Privatdocent (lecturer; paid from student fees, not on the state payroll). In 1824 and 1827 Bronn traveled to Switzerland, southern France, Austria, and northern Italy for field research. In 1828, back at Heidelberg, he was promoted to ausserordentlicher Professor(extraordinary professor) for topics in commerce and natural history. From 1830 on, he coedited the Jahrbuch(after 1833, the Neues Jahrbuch)für Mineralogie, Geognosie, Geologie, and Petrefaktenkunde (New yearbook for mineralogy, geognosy, geology, and fossil studies), which von Leonhard had founded in 1806. In 1833, he took over the directorship of the zoological collection and responsibility for teaching zoology. Finally, in 1837, he received his promotion to Ordinarius (ordinary, or full professor) and became head of Heidelberg’s first full-fledged institute of zoology, while also retaining responsibility for applied natural history. This places him among the first generation of zoologists to establish their field as a university-based discipline.

Bronn spent the rest of his career at Heidelberg. He rose to the rank of Hofrat (court councillor) in the civil service, and served as university Prorektor in 1859–1860. Bronn’s work in paleontology was honored with a gold medal from the Dutch Scientific Society in Haarlem and a prize from the French Academy of Sciences in 1857. He was married to Luise Bronn, née Penzel, and they had five children. Bronn died suddenly in 1862, apparently of a heart attack.

Paleontological Works—Overview. Bronn made his international reputation as a geologist and paleontologist between 1824 and 1831 with systematic works on fossil shells and zoophytes, and reports on the geology, paleontology, and economy of Heidelberg and of the regions he visited on his scientific travels. From 1835 to 1838 he brought out his Lethæa geognostica, the most complete compendium of fossil species of its time. By organizing fossils first by geological time period, and then taxonomically and geographically within each period, it put the organisms into concrete historical contexts instead of arranging them on a timeless scale of nature or in an abstract system. The arrangement also facilitated the practice, already widespread, of dating geological strata by the fossil species they contained. Other reference works followed, which featured alphabetical indexing and continued to add species and eliminate synonyms.

Handbuch einer Geschichte der Nature. Bronn’s three-volume Handbuch einer Geschichte der Natur (Handbook of a history of nature, 1841–1849) is not only a paleonto-logical reference work, but also a general introduction to natural history and Bronn’s major theoretical statement on the history of the organic world, the causes and laws of change, and the places of zoology and paleontology among the scientific disciplines. It stresses the unity of the sciences and the bearing of cosmology, geology, physics, and chemistry on the study of life. Beginning with the nebular hypothesis and the origin of Earth as a molten sphere, it argues that the gradually cooling Earth presented progressively more hospitable and diverse environments. Such geological progress, Bronn argued, together with the principle that species must always be adapted to their environments, explains the patterns (or “laws”) of species succession that are documented in the rest of the book.

Based on a study of variation, both in geographic varieties and artificially bred ones, Bronn decided against the possibility of species transformation. If a new species appears suddenly at some point in the fossil record, it must have been produced then and there by some creative force or process. Although the nature and causes of the creative force were unknown, Bronn could describe its effects and discover the laws that governed it. His most fundamental law (Grundgesetz) was that new species always had to be adapted to the environmental conditions they would actually encounter. Other, less fundamental laws saw to it that new creations stayed within taxonomic types, but also pushed their boundaries to make them include higher percentages of modern species, more “perfect,” and more diverse ones, and also to colonize a progression of environments, from the marine, to the freshwater, to the terrestrial.

Bronn’s law of adaptation implied that each species was suited to life at a particular time and place, and would gradually become less-well adapted as Earth evolved. Eventually it would diminish in numbers, become extinct, and be replaced by one or more better-adapted and more-advanced species. Because of complex interdependencies among species and environments, each extinction, in turn, triggered further extinctions, then further creations, resulting in continual turnover and improvement of the fauna and flora.

This successional theory of Bronn’s was one of several that were current in the decades before The Origin of Species, but it had several distinctive features. Against Louis Agassiz’s catastrophism, which had envisioned periodic mass extinctions and wholesale fresh creations of more advanced forms, Bronn argued for asynchronous extinctions and gradual species turnover. His detailed tabulations of fossils and their relative ages provided strong evidence against mass, simultaneous extinctions. In contrast, Bronn opposed the steady state uniformitarianism of Charles Lyell, which had gradual species turnover, but no net geological or morphological progress. Bronn’s data also allowed him to document and quantify various forms of advancement in the fossil record. In addition, Bronn also rejected the notion, associated with Naturphilosophie and idealistic morphology, that embryonic development could serve as the model for historical change. Bronn argued that the sequences of fossil forms did not run parallel to embryonic stages and that species did not have life cycles and predetermined life expectancies. Bronn viewed paleontology as a separate subdiscipline, with its own laws and its own data, and paleontologists were to explain organic change with reference to the changing external world, rather than internal, developmental processes.

Later Works on Zoology and Morphology. Bronn did not consider himself a narrow specialist on paleontology, but was also concerned with zoology as a whole and its emerging position among the academic disciplines. In the interest of providing zoology with a unifying conceptual framework, Bronn devoted his next major project to an encyclopedic Allgemeine Zoologie (General zoology). Here he outlined a view of the animal as a living whole, to which every subdiscipline contributed: anatomy, physiology, biochemistry, animal psychology, biogeography, pale-ontology, and systematics. The same unifying urge provided the impetus behind Bronn’s well-known series Klassen und Ordnungen des Thierreiches (Classes and orders of the animal kingdom), which was intended to give a complete account of every major animal group. Bronn produced the first three volumes between 1859 and 1862, and it has been continued by many other authors.

Bronn’s prizewinning Untersuchungen über die Entwickelungs-Gesetze der organischen Welt während der Bildungs-Zeit unserer Erd-Oberfläche (Investigations on the developmental laws of the organic world during the formative period of our Earth’s surface), originally written in French in 1855, first appeared in print in an 1858 German version. In it Bronn restated and refined his theory of organic history from Handbuch einer Geschichte der Natur. It was still a successional theory, rather than an evolutionary one, but the laws of change were much simplified and it was strongly suggested that they were all ultimately reducible to the effects of adaptation to an evolving Earth. Morphological progress was also measured by some new yardsticks, such as increasing “physiological division of labor,” a concept developed by Henri Milne-Edwards, who was one of the judges at the French Academy.

Also in 1858, Bronn published Morphologische Studien über die Gestaltungs-Gesetze der Naturkörper überhaupt und der organischen insbesondere (Morphological studies of the formative laws of natural bodies generally and organic ones in particular), an analysis of crystals, embryonic stages, and the diversity of adult forms. By publishing a separate book on this subject, Bronn underscored the distinction between the process of forming an animal body and the historical progression of forms in the fossil record. According to Bronn, embryonic and fossil sequences did indeed have many superficial similarities, because they both involved increasing complexity and division of labor, and they both had the same endpoints in present-day adult forms, but they were not to be equated. Because embryonic stages did not have to be adapted to historical environments, one should not expect them to run parallel to anything in the fossil record.

Bronn and Darwin. Despite its threat to overturn his own successional theory, Bronn responded constructively to the publication of The Origin of Species in 1859. He translated the second and third editions of Darwin’s book into German in 1860 and 1863, respectively, and he appended his own critical commentary to both of those editions. Bronn also translated Darwin’s book on orchids.

Bronn’s translation of The Origin has often been criticized for rendering Darwin’s new ideas in the language of an older German morphology, which spoke of natural selection leading to increasing “perfection” of form. Darwin’s supporters also objected to Bronn’s commentary, which gave at best an ambiguous endorsement of Darwinism. Still, it was the first translation on the market in any language, and it was instrumental in disseminating Darwin’s theory and initiating discussion in Germany. Starting with the 1867 third German edition (based on Darwin’s fourth), J. Victor Carus took over as Darwin’s principal German translator, and he removed Bronn’s commentary and modernized some of the terminology.

Bronn’s own work had anticipated Darwin’s emphasis on adaptation to changing environments and on the demise of the maladapted, and he was willing to reconsider the fixity of species and even the direction and purposefulness of historical progress. But in his commentary, he complained of Darwin’s inability to explain the origin of the very first species. As long as Darwin still allowed for a mysterious creative force to produce even one species long ago, Bronn argued, he had not really rid science of such forces or ruled out theories such as Bronn’s that relied solely on them. Bronn also raised the problem of orderliness in taxonomy, especially the distinctiveness of species. He thought that there was not, in fact, such a great chaos of unclassifiable species as Darwinian variation ought to produce. Bronn observed that nature had “lawlike means” of maintaining species’ identities and eventually returning varieties to the norm if they were ever altered by environmental influences, hybridization, or artificial selection. In contrast, under Darwin’s theory, such order had to be maintained by natural selection, which carved out recognizable species and higher groups. But Darwin had no direct historical evidence that it always did so and, worst of all, nothing like a law of nature requiring it. The whole scheme seemed to Bronn to be too capricious to be a proper scientific explanation of life. Bronn rejected the theory as it then stood, but predicted that the Darwinians would eventually gain acceptance.

BIBLIOGRAPHY

WORKS BY BRONN

System der Urweltlichen Konchylien. Heidelberg, Germany: J.C.B. Mohr, 1824.

System der Urweltlichen Pflanzenthiere. Heidelberg, Germany: J.C.B. Mohr, 1825.

Ergebnisse meiner naturhistorisch-ökonomischen Reisen. Heidelberg, Germany: Karl Groos, 1826.

Gæa Heidelbergensis: Oder, mineralogische Beschreibung der Gegend von Heidelberg. Heidelberg, Germany: Karl Groos, 1830.

Lethæa geognostica: Oder Abbildungen und Beschreibungen der für die Gebirgs-Formationen bezeichnendsten Versteinerungen. Stuttgart, Germany: E. Schweizerbart, 1835.

Handbuch einer Geschichte der Natur. 3 vols. and atlas. Stuttgart, Germany: E. Schweizerbart, 1841–1849.

Index palaeontologicus: Oder Übersicht der bis jetzt bekannten fossilen Organismen. Stuttgart, Germany: E. Schweizerbart, 1848.

Allgemeine Zoologie. Stuttgart, Germany, 1850. Morphologische Studien über die Gestaltungs-Gesetze derNaturkörper überhaupt und der organischen insbesondere. Leipzig, Germany: C.F. Winter, 1858.

Untersuchungen über die Entwickelungs-Gesetze der organischen Welt während der Bildungs-Zeit unserer Erd-Oberfläche. Stuttgart, Germany: E. Schweizerbart, 1858. Die Klassen und Ordnungen der formlosen Thiere (Amorphozoa). Vol. 1: Wissenschaftlich dargestellt in Wort und Bild. Leipzig, Germany: C.F. Winter, 1859.

Review of On the Origin of Species by Means of Natural Selection, Or the Preservation of Favoured Races in the Struggle for Life, by Charles Darwin (1859). Neues Jahrbuch für Mineralogie, Geognosie, Geologie und Pertefaktenkunde (1860): 112–116. Translated by David Hull as: “Review of the Origin of Species.” In Darwin and His Critics: The Reception of Darwin’s Theory of Evolution by the Scientific Community, edited by David L. Hull. Cambridge, MA: Harvard University Press, 1973.

Die Klassen und Ordnungen der Strahlenthiere (Actinozoa). Vol. 2: Wissenschaftlich dargestellt in Wort und Bild. Leipzig, Germany: C.F. Winter, 1860.Translator. Über die Entstehung der Arten im Thier- und Pflanzen-Reich durch natürliche Züchtung, oder Erhaltung der vervollkommneten Rassen im Kampfe um’s Daseyn. 1st German ed. Stuttgart, Germany: E. Schweizerbart, 1860. Translation of the second English edition of The Origin of Species by Charles Darwin.

Essai d’une réponse à la question de prix proposée en 1850 par l’Académie des Sciences. Paris: Mallet-Bachelier, 1861.

Die Klassen und Ordnungen der Weichthiere (Malacozoa). Vol. 3, part 1: Wissenschaftlich dargestellt in Wort und Bild. Leipzig, Germany: C.F. Winter, 1862.

Translator. Über die Entstehung der Arten im Thier- und Pflanzen-Reich durch natürliche Züchtung, oder Erhaltung der vervollkommneten Rassen im Kampfe um’s Daseyn. 2nd ed. Stuttgart, Germany: E. Schweizerbart'sche Verlagshandlung und Druckerei, 1863. Translation of the third English edition of The Origin of Species by Charles Darwin.

Neues Jahrbuch für Mineralogie, Geognosie, Geologie undPetrefaktenkunde. Stuttgart, Germany: E. Schweizerbart. Edited by Karl Cäsar von Leonhard and H. G. Bronn, this journal contains numerous research papers and reviews by Bronn.

OTHER SOURCES

Baron, Walter. “Zur Stellung von Heinrich Georg Bronn (1800–1862) in der Geschichte des Evolutionsgedankens.” Sudhoffs Archiv für Geschichte der Medizin und der Naturwissenschaften 45 (1961): 97–109.

Gliboff, Sander. “H. G. Bronn and the History of Nature.” Journal of the History of Biology (in press).

Gümbel. “Bronn: Heinrich Georg.” In Allgemeine DeutscheBiographie. Leipzig, Germany: Duncker & Humblot, 1876. Junker, Thomas. “Heinrich Georg Bronn und die Entstehung der Arten.”Sudhoffs Archiv für Geschichte der Medizin und der Naturwissenschaften 75 (1991): 180–208.

Nyhart, Lynn K. Biology Takes Form: Animal Morphology and theGerman Universities, 1800–1900. Chicago: University of Chicago Press, 1995. Chapter 4 places Bronn within the history of morphology as an academic discipline.

Schumacher, Ingrid. “Die Entwicklungstheorie des Heidelberger Paläontologen und Zoologen Heinrich Georg Bronn (1800–1862).” Diss., Ruprecht-Karls-Universität, Heidelberg, Germany, 1975. Still the best overview of Bronn’s life and work, with an emphasis on his contributions to theory.

Sander Gliboff

Bronn, Heinrich Georg

(b. Ziegelhausen bei Heidelberg, Germany, 3 March 1800; d. Heidelberg, Germany, 5 July 1862)

paleontology, zoology.

Fundamental systematic works in paleontology are Bronn’s most enduring contribution to science. He was educated in public administration and natural science in Heidelberg, after which he traveled through northern Italy and southern France, making paleontological investigations. In 1833 he became professor of natural science at Heidelberg. For a short time Louis Agassiz studied with Bronn, and decades later returned to purchase Bronn’s collection of fossils for the newly established Museum of Comparative Zoology at Harvard.

In 1831 Bronn’s Italiens Tertiär-Gebilde distinguished different series of Tertiary strata on the principle that in successively more recent strata the number of extinct species diminishes while the number of modern species increases. His divisions correspond closely to those established as Eocene, Miocene, Older Pliocene, and Newer Pliocene in Lyell’s Principles of Geology (1833). Bronn’s extensive Lethaea geognostica, which sought to establish a chronological sequence of fossil organisms, summarized all that was then known in stratigraphy and paleontology. His later Index palaeontologicus and the Lethaea geognostica were for decades the chief reference works in paleontology. At his death Bronn left unfinished the enormous undertaking of systematizing the whole animal kingdom, recent as well as fossil forms, in Die Klassen und Ordnungen des Thier-reichs. From 1830 he edited the Jahrbuch für Mineralogie, Geognosie, Geologie, und Petrefackten-kunde with Karl von Leonhard, and later with Georg von Leonhard. Soon after Darwin’s Origin of Species appeared in 1859, Bronn, at Darwin’s suggestion, was responsible for having it translated into German.

Near the end of his life Bronn synthesized developmental laws of nature from his extensive and detailed paleontological studies. He rejected theories of development like those of Lamarck and Geoffroy St. Hilaire and the modification of one species into another. Instead, he explained progressive development, “the successive appearance of forms with more and more complicated organization,” by a law of creation operating according to a definite plan. Species became extinct and were replaced by improved ones within the limits imposed by the external “conditions of existence.” Bronn used this phrase, borrowed from Cuvier, to indicate adaptation to environment rather than functional harmony, as Cuvier had. The conditions of existence, which exerted a negative, restricting effect on organic development, varied as the earth’s crust evolved. During the formation of the crust the primitive ocean was first modified by the appearance of islands and mountain chains, which then grew into continents, thereby dividing the earth’s surface into separate oceans, inland seas, lakes, coastal plains, and mountain ranges. The organic kingdoms adhered to a law of terripetal evolution analogous to the development of the crust. At first entirely pelagic, they evolved littoral, then coastal, and finally continental forms.

Bronn emphasized that these changes, both organic and inorganic, had been gradual and continuous. Like many of his contemporaries, he criticized the new glacial theory of Louis Agassiz because it appeared to introduce a catastrophe into the history of the world. Bronn argued that the gaps then acknowledged in the paleontological and stratigraphic succession were illusory and would be bridged by the future discovery of transitional species and intermediate formations. (Compare Darwin’s similar essay, “On the Imperfection of the Geological Record,” Origin of Species, ch. 9.)

Bronn’s contributions, both theoretical and systematic, were recognized by his contemporaries. In 1857 his “Laws of Evolution of the Organic World” won the prize of the Academy of Sciences of Paris. For the Handbuch einer Geschichte der Natur he was awarded a prize medal by the Scientific Society of Haarlem, and in 1861 he received the Wollaston Prize of the Geological Society of London.

BIBLIOGRAPHY

Bronn’s main theoretical contributions are found in his Untersuchungen über die Entwicklungsgeschichte der organischen Welt während der Bildungszeit unserer Erdoberfläche (Stuttgart, 1858), of which the last chapter, summarizing the whole work, is available in English in The Annals and Magazine of Natural History, 3rd ser., 4 (1859), 81–90, 175–184.

His more important classificatory and descriptive works are Gaea Heidelbergensis, oder Mineralogische Beschreibung der Gegend von Heidelberg (Heidelberg, 1830); Italiens Tertiär-Gebilde und deren organischen Einschlüsse (Heidelberg, 1831); Lethaea geognostica, oder Abbildungen und Beschreibungen der für die Gebirgs-Formationen bezeichnendsten Versteinerungen, 2 vols. (Stuttgart, 1835–1838 and several later editions); Handbuch einer Geschichte der Natur, 2 vols. (Stuttgart, 1841–1843), which includes as its third part Index palaeontologicus, a systematic reduction of all published lists of fossils; and Die Klassen und Ordnungen des Thier-reichs, wissenschaftlich dargestellt in Wort und Bild (begun in 1859 and continued after Bronn’s death), paleontology and zoology combined in one system.

For a list of his memoirs, see the Royal Society Catalogue of Scientific Papers, I, VII.

For biographical information, see the obituary notice in the Quarterly Journal of the Geological Society of London, 19 (1863), xxxii–xxxiii.

Bert Hansen