BAER Karl Ernst von—an investigator and philosopher of nature, b. 29 February 1792 in Piep (Piip—Estonia), d. 28 November 1876 in Dorpat (presently Tartu—Estonia).

After studies in Dorpat, Vienna, Würzburg, and Berlin, from 1819 to 1834 he conducted natural investigations and taught in Królewiec (Königsburg). In 1834 he moved to Saint Petersburg in Russia where from 1828 he was an ordinary member of the Petersburg Academy of the Sciences and accepted in the Academy the function of second zoologist, and a year later also the function of librarian of the foreign section of the Academy. He also performed many administrative functions. After he moved to Russia he no longer studied embryology and became interested in geography. He made many remarks on trips to northern Russia and the Caspian Sea. He was the first to collect many natural specimens from the still uninhabited lands of Novaya Zemlya. As he travelled through the lands of Russia he became interested in the scientific and practical aspects of catching fish. Taking as his foundation the results of observations of sculpture and the proportion of the magnitude of the banks of Russian rivers, he showed that the orbital motion of the Earth is the cause of assymetry between the height of the eastern and western bank of a river. In his trips about Russia he also devoted attention to investigations in ethnography. A small part of his scientific work concerns archeology. He gathered a considerable collection of human skulls for the Petersburg Academy of the Sciences. After he measured them he prepared a work that presented at a conference of craniologists he convoked in 1861 in Germany. This conference marked the beginning of the German Anthropological Society. Baer was also the founder of the Russian Entomological Society. In 1862 he ceased to be an active member of the Petersburg Academy of the Sciences but for the next five years was involved in its works as an honorary member. He was the author of over three hundred publications. In recognition of Baer’s contributions in different fields of science, he was elected as a member of the nine academies of science. He is regarded as one of the most influential scholars of the nineteenth century.

Baer’s major contribution is the natural sciences consist in his many fundamental discoveries in biology, especially in the individual development (ontogenesis) of animals. These contributions include the discovery of ova in mammals, the blastula (a stage in embryonic development common to all animals), and the notocord. Thereby the framework of the comparative embryology of animal kingdon was established. Baer made his major accomplishments in embryology by scrupulous observations, mainly on chicken embryos. He formulated an important generalization, that all mammals develop from an egg cell (De ovi mammalium et hominis genesi epistola ad Academiam Imperialem Scientiarum Petropolitanam, L 1827). Using his findings, he developed a systematic presentation (Über Entwicklungsgeschichte der Tiere, I–II, Kgb 1828–1837) on the individual development of animals from one cell to hatching or birth. He was opposed to the widespread belief at the time that the embryonic development of an animal of a particular species occurs in stages, in which embryos become similar to the adult individuals of other species. On the contrary, he stated the only similarity that occurs is between embryos of particular species, and the similarity is greater the earlier the stage of development. This assertion reflected his belief that was a middle position between epigenetic and preformistic assertions. He thought that although animal embryos are not found in the gamete as completely formed and miniature, in the previously undifferentiated matter organizing forces operate that properly form the embryo. Their operation is first manifested in the center of the developing system (this is the spinal cord in a verterbrate), and later in the peripheral part. The assertion that the embryo passes through stages of development that follow each other in regular fashion began to play a fundamental role in embryology from that time. In general form it states that development starts from what is general and aims at what is specific, or in other terms, from a homogeneous state to a heterogenous state. The second formulation played a fundamental role H. Spencer’s theory of all- embracing evolution.

The significance of Baer’s work for the philosophy of nature consists in the presentation and defence of the conception of nature as one great whole governed by the laws of causality and teleology (Baer’s positions were collected in: Reden gehalten im wissenshaftlichen Versammlungen und kleinere Aufsätze vermischten Inhalts I–III, Ptb 1864–1876). In a work on human skulls published in 1859, Baer suggested that some human races may originate from one common form that once existed. Changes the races may have occured because of changes in the organism caused by environmental factors. Although in this he anticipated C. Darwin’s theory of the origin of species published in the same year, and especially the later works in which we read of the emergence of the human species from previously existing forms, Baer later recognized this suggestion as being of little value. He also thought little of the view he had expressed in his youth that human beings can originate (anthropogenesis) directly from forms living in seawater. In the later period of his life he was firmly opposed to the position that human beings originated from animal ancestors, although he admitted the possibility that the first human being could have arisen because of a sudden change of properties (mutation) in the fertilized egg-cell of a mammal living in the Quaternary period.

Baer stood at a great distance from C. Darwin’s theory of evolution. Baer thought that we may treat it at best as an interesting scientific hypothesis, but in no case was it the crowning point of scientific knowledge. He regarded the complete elimination of teleology from nature as an essential shortcoming in Darwin’s theory. He was also firmly opposed to Darwin’s view on the essential role of natural selection in the origin of new species. He regarded as a fantasy Darwin’s view that sexual selection played an important role in the origin of the human species. He still thought that new forms of the organic world could come into being. This could happen only on the basis of origin—caused by the influence of external factors—of different variations within a specific type of their organization. Like G. Cuvier he thought that all animals are variants within one of the four organizational types.

In his philosophical works (and in natural history, which also contained such lines of thought) he expressed his belief that particular organisms and nature as whole are teleologically organized wholes that develop according to a higher creative principle. The development occurs in accordance with the laws of nature and aspires to a predetermined goal. Baer’s earlier views on these most general questions may be regarded as pantheism. His later beliefs have a definitely theistic character. He ascribed great value to the desire to reconcile data supplied by knowledge (especially scientific knowledge) with the truths of faith. Where the data are in conflict with both these regions, he was inclined to ascribe greater rank to data supplied by reason and experience. He thought that while it is possible to know that God exists, we cannot know his nature. He acknowledged the existence of the immortal human soul and was opposed to the view that consciousness can be explained in terms of physico-chemical processes. He was an evangelical Lutheran. He appreciated the significance of religion in social life, although he did not take part in religious life except on exceptional occasions.

He was firmly opposed to materialism and supported vitalism. For this reason Baer’s views were criticized and even mocked in his own time. In the question of how to approach the essence of man’s spirituality and the role of spirit in nature he was particularly opposed to the views of Darwin and his followers (E. Haeckel, T. Huxley). In his studies he absorbed the views of F. Schelling and during a scientific career that spanned over fifty years he expressed the idea of the development that the world developed toward increasingly higher levels of perfection and ultimately to the victory of spirit over matter.

It is ironic that Baer’s laws of embryonic development (Baer’s law) were used by E. Haeckel to formulate the so-called biogenetic law. Baer firmly opposed the uses and abuses of the biogenetic law. Moreover, the creation of solid foundation (1827) for embryology made it possible later to gather together many empirical data that appear as one of the most powerful arguments for the evolutionary origin of the species of the organic world.

L. Stieda, Karl Ernst von Baer. Eine biographische Skizze, Brunschwieg 18862; R. Stölzle, Karl Ernst von Baer und seine Weltanschaung, Rb 1897; idem, Karl Ernst von B. Stellung zum Problem der Zweckmässigheit, Biol. Zbl. 20 (1900), 34–45; idem, Karl Ernst von B. Stellung zur Frage nach Abstammung des Menschen, Biol. Zbl. 20 (1900), 465–479, 503–508; idem, Karl Ernst von B. Schriften, St 1907; G. Sarton, The Discovery of the Mammalian Egg and the Foundation of Modern Embryology, Isis 16 (1936), 315–330; B. E. Raikov, Karl Ernst von Baer, 1792–1876, sein Leben und sein Werk, L 1968; J. Oppenheimer, in: Dictionary of Scientific Biographies, NY 1970, I 385–389.

Józef Zon

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