Karl Ernst von Baer was a German-Estonian anatomist, embryologist, biologist, anthropologist, and geographer. He was the first to describe the mammalian ovum. He is also noted for the development of the germ-layer theory, which became the basis for modern embryology.
Background
Ethnicity:
Karl Ernst von Baer was born into the Baltic German noble Baer family. He was descended from an originally Prussian family. Many of his ancestors had come from Westphalia.
Karl Ernst von Baer was born on February 29, 1792 into a Baltic German noble family in the Piep estate, Kreis Jerwen, Governorate of Estonia (in present-day Lääne-Viru County, Estonia), as a knight by birthright. He spent his early childhood at Lasila manor, Estonia.
Education
Although his uncle and father encouraged military life, von Baer chose to attend the University of Dorpat, where he began medical studies in August 1810. At Dorpat, von Baer studied botany, physics, and physiology, and was influenced by professor of physiology Karl Friedrich Burdach. After completing his MD degree in September 1814, von Baer traveled to Berlin and Vienna to continue his education. In 1815 he proceeded to Würzburg to further his medical studies and there he met physiologist and anatomist Ignaz Döllinger as a result of his interest in botany. From 1815–1816 von Baer studied comparative anatomy with Döllinger, who encouraged him to research the development of the chick. However, von Baer was unwilling or unable to spend the time and money necessary to pursue this area of study and instead returned to Berlin during the winter of 1816–1817 to train in practical anatomy.
Career
In August 1817 von Baer became a prosector in anatomy in Königsberg at the invitation of Karl Friedrich Burdach. In 1819 he became Extraordinary Professor of Anatomy and in 1826 Ordinary Professor of Zoology. During his time in Königsberg, von Baer taught zoology, anatomy, and anthropology, founded a zoological museum, acted as director of the botanical gardens, and served as dean of the medical faculty and as rector of the university.
Most of von Baer’s contributions to embryology were from 1819–1834 while at Königsberg. During this time, he returned to the study of embryology and made considerable advances in the understanding of extraembryonic membrane development and function in the chick and in mammals. In this work he built on the results of research he had carried out collaboratively in Würzburg with Christian Heinrich Pander, as well as on Pander’s own work on chick embryology. Karl Ernst von Baer also introduced the term “spermatozoa”, for what had previously been referred to as “animalcules” in the seminal fluid, which he believed to be parasites. In 1826 von Baer discovered mammalian eggs in the ovary of Burdach’s dog, completing a search that began centuries before.
Drawing a number of conclusions from his work on developing embryos, von Baer emphasized that development is epigenetic, proceeding from homogeneous to heterogeneous matter, which he felt made preformationist ideas no longer plausible. He encapsulated his thinking into four statements that are now known as “von Baer’s Laws.” The first law says that the general features of a large group of animals appear earlier in the embryo than the special features. The second law says that less general characters are developed from the most general, and so forth, until finally the most specialized appear. The third law is that instead of passing through the stages of other animals, each embryo of a given species departs more and more from them. Finally, the fourth law concludes from the previous three that the embryo of a higher animal is never like the adult of a lower animal, but only like its embryo.
After the death of his brother Louis, von Baer returned with his family to St. Petersburg to retain the family estate. He then entered the Academy of Sciences in St. Petersburg as a Full Member in Zoology in December 1834 after refusing previous offers while in Königsberg. After working at the academy as a librarian, academician, and professor of anatomy and physiology, von Baer retired from active membership in 1862 but continued to work as an honorary member until 1867. After returning to Dorpat, von Baer died on 28 November 1876.
Politics
Baer was a patriotic Russian, as is clear from the zeal with which he carried out his duties for the academy and from his evident interest in Russian geography and ethnography. But he was also an expressed enthusiast of Prussia. His true political views remain obscure, for some were expressed cryptically and others, we are told by his biographer Stieda, were probably eliminated from his publications by the censors.
Views
Baer classified man into six categories, ranked according to the degree of primitiveness. His interpretations of some peoples as more primitive than others were similar to those of his contemporaries and immediate predecessors; he did not bring to this area of investigation the same vision that he had carried into embryology. Nonetheless, at least one of his contributions to modern anthropology was truly effective. After he became academician for comparative anatomy and physiology, one of his primary accomplishments, perhaps growing out of his earlier museum experience in Königsberg, was the establishment at the academy of a craniological collection. Attempts to classify skulls were based on measurements, and Baer thought it desirable that methods of cranial measurement be standardized. To this end, he called together a group of craniologists in Göttingen in 1861. The measurements were not standardized, but the meeting led to the founding of the German Anthropological Society and of the German Archiv für Anthropologie.
Quotations:
"All new ideas pass through three stages: first they are dismissed as nonsense, then they are rejected as being against religion and finally they are acknowledged as the truth, with the proviso from the initial opponents that they knew it all along."
"Know thyself! This is the source of all wisdom, said the great thinkers of the past, and the sentence was written in golden letters on the temple of the gods. To know himself, Linnæus declared to be the essential indisputable distinction of man above all other creatures. I know, indeed, in study nothing more worthy of free and thoughtful man than the study of himself. For if we look for the purpose of our existence, we cannot possibly find it outside ourselves. We are here for our own sake."
"The History of Evolution is the real source of light in the investigation of organic bodies. It is applicable at every step, and all our ideas of the correlation of organic bodies will be swayed by our knowledge of the history of evolution. To carry the proof of it into all branches of research would be an almost endless task. (1828)"
"The development of the Vertebrate proceeds from an axis upward, in two layers, which coalesce at the edges, and also downward, in two layers, which likewise coalesce at the edges. Thus two main tubes are formed, one above the other. During the formation of these, the embryo separates into strata, so that the two main tubes are composed of subordinate tubes which enclose each other as fundamental organs, and are capable of developing into all the organs."
Membership
Baer was a foreign honorary member of the American Academy of Arts and Sciences from 1849, a foreign member of the Royal Swedish Academy of Sciences from 1850, a member of the Estonian Naturalists' Society (1869 - 1876), and a member of the Russian Entomological Society. In 1875, he became a foreign member of the Royal Netherlands Academy of Arts and Sciences.