Curt Paul Richter (February 20, 1894 – December 21, 1988) was an American

biologist A biologist is a scientist who conducts research in biology. Biologists are interested in studying life on Earth, whether it is an individual Cell (biology), cell, a multicellular organism, or a Community (ecology), community of Biological inter ...

psychobiologist Behavioral neuroscience, also known as biological psychology, biopsychology, or psychobiology,Psychobi ...

and

geneticist A geneticist is a biologist or physician who studies genetics, the science of genes, heredity, and variation of organisms. A geneticist can be employed as a scientist or a lecturer. Geneticists may perform general research on genetic process ...

who made important contributions in the field of

circadian rhythm A circadian rhythm (), or circadian cycle, is a natural oscillation that repeats roughly every 24 hours. Circadian rhythms can refer to any process that originates within an organism (i.e., Endogeny (biology), endogenous) and responds to the env ...

s. Notably, Richter identified the

hypothalamus The hypothalamus (: hypothalami; ) is a small part of the vertebrate brain that contains a number of nucleus (neuroanatomy), nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrin ...

as a "biological pacemaker" involved in sleeping and wakefulness. In particular, this region suspected by Richter was later identified as the

suprachiasmatic nucleus The suprachiasmatic nucleus or nuclei (SCN) is a small region of the brain in the hypothalamus, situated directly above the optic chiasm. It is responsible for regulating sleep cycles in animals. Reception of light inputs from photosensitive r ...

Early life, family and education

Richter was born on February 20, 1894, in

Denver Denver ( ) is a List of municipalities in Colorado#Consolidated city and county, consolidated city and county, the List of capitals in the United States, capital and List of municipalities in Colorado, most populous city of the U.S. state of ...

Colorado Colorado is a U.S. state, state in the Western United States. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas ...

, to German immigrants from

Saxony Saxony, officially the Free State of Saxony, is a landlocked state of Germany, bordering the states of Brandenburg, Saxony-Anhalt, Thuringia, and Bavaria, as well as the countries of Poland and the Czech Republic. Its capital is Dresden, and ...

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

. Richter's father was an engineer who owned a steel and iron firm in Denver. In 1912, Richter studied engineering at a

Technische Hochschule A ''Technische Hochschule'' (, plural: ''Technische Hochschulen'', abbreviated ''TH'') is a type of university focusing on engineering sciences in Germany. Previously, it also existed in Austria, Switzerland, the Netherlands (), and Finland (, ) ...

in Germany, but he left after the outbreak of

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

in 1914, switching to

Harvard University Harvard University is a Private university, private Ivy League research university in Cambridge, Massachusetts, United States. Founded in 1636 and named for its first benefactor, the History of the Puritans in North America, Puritan clergyma ...

where he studied biology under William E. Castle. Due to Richter's lack of experience with biology, Castle advised that he drop the course, so he switched to psychology instead, studying under

E. B. Holt Edwin Bissell Holt (; August 21, 1873 – January 25, 1946) was an American professor of philosophy and psychology at Harvard from 1901–1918. From 1926–1936, he was a visiting professor of psychology at Princeton University. Biography Holt wa ...

and

Robert Yerkes Robert Mearns Yerkes (; May 26, 1876 – February 3, 1956) was an American psychologist, ethologist, eugenicist and primatologist best known for his work in intelligence testing and in the field of comparative psychology. Yerkes was a pionee ...

. He graduated from Harvard in 1917 and, after a brief tour in the

United States Army The United States Army (USA) is the primary Land warfare, land service branch of the United States Department of Defense. It is designated as the Army of the United States in the United States Constitution.Article II, section 2, clause 1 of th ...

, studied under John Watson at

Johns Hopkins University The Johns Hopkins University (often abbreviated as Johns Hopkins, Hopkins, or JHU) is a private university, private research university in Baltimore, Maryland, United States. Founded in 1876 based on the European research institution model, J ...

Work

Richter induced need states in experimental animals by depriving them of substances essential to survival, or manipulating their

hormone A hormone (from the Ancient Greek, Greek participle , "setting in motion") is a class of cell signaling, signaling molecules in multicellular organisms that are sent to distant organs or tissues by complex biological processes to regulate physio ...

levels. He showed that these need states generate appetites, and behaviors precisely fitting the animal's need even if the animal had never before experienced the need; demonstrating

genetic programming Genetic programming (GP) is an evolutionary algorithm, an artificial intelligence technique mimicking natural evolution, which operates on a population of programs. It applies the genetic operators selection (evolutionary algorithm), selection a ...

of behavior. He also triggered other pre-programmed behaviors, such as nest building, by manipulating hormone levels. Richter was elected to the United States

National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, NGO, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the ...

in 1948, the

American Academy of Arts and Sciences The American Academy of Arts and Sciences (The Academy) is one of the oldest learned societies in the United States. It was founded in 1780 during the American Revolution by John Adams, John Hancock, James Bowdoin, Andrew Oliver, and other ...

in 1956, and the

American Philosophical Society The American Philosophical Society (APS) is an American scholarly organization and learned society founded in 1743 in Philadelphia that promotes knowledge in the humanities and natural sciences through research, professional meetings, publicat ...

in 1959.

In popular culture

Richter is quoted widely for his drowning rat experiments, where rats would drown in a fairly short time without attempting to swim. But if rats had repeated experiences of rescue (or of being held briefly and then freed) they "do not die", and "show no signs of giving up". As described in the paper:

Support for the assumption that the sudden death phenomenon depends largely on emotional reactions to restraint or immersion comes from the observation that after elimination of the hopelessness the rats do not die. This is achieved by repeatedly holding the rats briefly and then freeing them, and by immersing them in water for a few minutes on several occasions. In this way the rats quickly learn that the situation is not actually hopeless; thereafter they again become aggressive, try to escape, and show no signs of giving up. Wild rats so conditioned swim just as long as domestic rats or longer.

This has been interpreted as an argument for the importance of hope and recirculates on the internet regularly.

References

External links

''Medical Archives''
* 1894 births 1988 deaths Harvard University alumni Johns Hopkins University alumni Members of the American Philosophical Society 20th-century American biologists American geneticists Scientists from Denver 20th-century United States Army personnel Members of the United States National Academy of Sciences Fellows of the American Academy of Arts and Sciences APA Distinguished Scientific Award for an Early Career Contribution to Psychology recipients {{US-biologist-stub