Bernhard Rensch (21 January 1900 – 4 April 1990) was a German
evolutionary biologist
Evolutionary biology is the subfield of biology that studies the evolutionary processes (natural selection, common descent, speciation) that produced the diversity of life on Earth. It is also defined as the study of the history of life for ...
and
ornithologist who did field work in
Indonesia
Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...
and
India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
. Starting his scientific career with pro-Lamarckian views, he shifted to selectionism and became one of the architects of the
modern synthesis
Modern synthesis or modern evolutionary synthesis refers to several perspectives on evolutionary biology, namely:
* Modern synthesis (20th century), the term coined by Julian Huxley in 1942 to denote the synthesis between Mendelian genetics and s ...
in evolutionary biology, which he popularised in Germany. Besides his work on how environmental factors influenced the evolution of
geographically isolated populations and on evolution above the species level, which contributed to the modern synthesis, he also worked extensively in the area of animal behavior (
ethology
Ethology is the scientific study of animal behaviour, usually with a focus on behaviour under natural conditions, and viewing behaviour as an evolutionarily adaptive trait. Behaviourism as a term also describes the scientific and objecti ...
) and on philosophical aspects of biological science. His education and scientific work were interrupted by service in the German military during both
World War I
World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...
and
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...
.
Biography
Rensch was born in
Thale
Thale () is a town in the Harz district in Saxony-Anhalt in central Germany. Located at the steep northeastern rim of the Harz mountain range, it is known for the scenic Bode Gorge stretching above the town centre.
Geography
The town is situated ...
and as a young boy, he took an interest in observing the natural world and discovered a talent for drawing and painting. He served in the German army from 1917–1920 and began to observe natural phenomena while he was held prisoner in France. He returned to Germany and began his studies on feather structure under
Valentin Haecker
Ferdinand Carl Valentin Haecker (15 September 1864 – 19 December 1927) was a German zoologist, reader at Freiburg University from 1892.
In 1900, he became professor at the University of Applied Sciences Stuttgart and in 1909 at Martin Luther ...
(1864–1927) who had himself studied under
August Weismann
August Friedrich Leopold Weismann FRS (For), HonFRSE, LLD (17 January 18345 November 1914) was a German evolutionary biologist. Fellow German Ernst Mayr ranked him as the second most notable evolutionary theorist of the 19th century, after Cha ...
. Until the 1930s Rensch held anti-Darwinian and Lamarckian views. Rensch also took an interest in the philosophy of science and was fascinated by
Theodor Ziehen
Georg Theodor Ziehen (12 November 1862 – 29 December 1950) was a German neurologist and psychiatrist born in Frankfurt am Main. He was the son of noted author, Eduard Ziehen (1819–1884).
Education and career
As a gymnasium student, Ziehen s ...
(1862–1950). Rensch also studied expressionist painting and in later life examined the biological roots of art. He received his Ph.D. from the
University of Halle
Martin Luther University of Halle-Wittenberg (german: Martin-Luther-Universität Halle-Wittenberg), also referred to as MLU, is a public, research-oriented university in the cities of Halle and Wittenberg and the largest and oldest university in ...
in 1922. He joined the zoological museum of the University of Berlin as an assistant in 1925. In 1927 he participated in a zoological expedition to the
Sunda Islands.
He studied the geographical distribution of subspecies of
polytypic species and of complexes of closely related species with attention to how local environmental factors, especially climate, influenced their evolution.
In 1929 he published the book ''Das Prinzip geographischer Rassenkreise und das Problem der Artbildung'' that discussed the relationship between geography and speciation. His work in this area would influence
Ernst Mayr, who was also an assistant at the museum from 1927–1930, and would contribute to the development of the
modern evolutionary synthesis. In 1937 he was forced to leave the museum because he refused to join the Nazi party, and took a position at a zoological garden in
Münster
Münster (; nds, Mönster) is an independent city (''Kreisfreie Stadt'') in North Rhine-Westphalia, Germany. It is in the northern part of the state and is considered to be the cultural centre of the Westphalia region. It is also a state di ...
.
In 1940 he was recalled for military service, but was discharged for medical reasons in 1942.
In 1947 he published a book that would later be translated into English under the title ''Evolution above the species level''. The book discussed how the evolutionary mechanisms that drove speciation could also explain the differences between higher
taxa
In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...
. He introduced the concept of ''Artenkreis'' (which Mayr translated as a "superspecies" and defined as "a monophyletic group of closely related and largely or entirely allopatric species”). It was considered a major document in the modern synthesis. That same year he became chairman of the zoology department and director of the zoological institute at the University of Münster. In 1953 he would take part in a zoological expedition to India. Later in his career he would work extensively in the areas of animal behavior (
ethology
Ethology is the scientific study of animal behaviour, usually with a focus on behaviour under natural conditions, and viewing behaviour as an evolutionarily adaptive trait. Behaviourism as a term also describes the scientific and objecti ...
), learning, and memory.
Rensch also wrote on human behaviour and he suggested that the human evolutionary connection with organisms would lead to sympathy. He published an autobiography in 1979 and remained scientifically active until his death in 1990.
Biological rules
Rensche sought out
universal patterns in biology. He was responsible for naming
Allen's Rule
Allen's rule is an ecogeographical rule formulated by Joel Asaph Allen in 1877, broadly stating that animals adapted to cold climates have thicker limbs and bodily appendages than animals adapted to warm climates. More specifically, it states that ...
and
Gloger's Rule
Gloger's rule is an ecogeographical rule which states that within a species of endotherms, more heavily pigmented forms tend to be found in more humid environments, e.g. near the equator. It was named after the zoologist Constantin Wilhelm Lambe ...
, and proposed what is now called
Rensch's rule in 1950. It is an allometric law about the relationship between sexual size dimorphism and which sex is larger. It observes that across species size dimorphism increases with increasing body size when the male is the larger sex, and decreases with increasing average body size when the female is the larger sex.
Awards and recognition
He was awarded the
Linnean Society of London
The Linnean Society of London is a learned society dedicated to the study and dissemination of information concerning natural history, evolution, and taxonomy. It possesses several important biological specimen, manuscript and literature colle ...
's prestigious
Darwin-Wallace Medal in 1958.
Since 2004, the Society for Biological Systematics (GfBS, Germany) has awarded the Bernhard Rensch prize for achievements of young scientists, writing in German or English, in the field of systematics and biodiversity research.
A species of Indonesian lizard, ''
Cryptoblepharus renschi'', is named in his honor.
Works
This is a select list of books alone and includes English translations.
*(1930) ''Eine biologische Reise nach den kleinen Sunda-Inseln''. Berlin: Bornträger
*(1947)
*(1947) ''Evolution above the Species Level''. London: Methuen. (German original 1947; 3rd enlarged ed. 1972.)
*(1971) ''Biophilosophy''. New York: Columbia University Press. (German original 1968.)
*(1972) ''Homo sapiens: From Man to Demigod''. London: Methuen. (German original 1959.)
*(1973) ''Gedächtnis, Begriffsbildung und Planhandlungen bei Tieren''. Berlin: Parey.
*(1979) ''Lebensweg eines Biologen in einem turbulenten Jahrhundert''. Stuttgart: Fischer.
*(1979) ''Gesetzlichkeit, psychophysischer Zusammenhang, Willensfreiheit und Ethik''. Berlin: Duncker and Humblot.
*(1984) ''Psychologische Grundlagen der Wertung bildender Kunst''. Essen: Die blaue Eule.
*(1985) ''Biophilosophical Implications of Inorganic and Organismic Evolution''. Essen: Die blaue Eule.
References
{{DEFAULTSORT:Rensch, Bernhard
1900 births
1990 deaths
People from Thale
People from the Province of Saxony
20th-century German biologists
Evolutionary biologists
Modern synthesis (20th century)
University of Münster faculty
Foreign associates of the National Academy of Sciences