Calvin Blackman Bridges (January 11, 1889 – December 27, 1938) was an American scientist known for his contributions to the field of

genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar wor ...

. Along with

Alfred Sturtevant Alfred Henry Sturtevant (November 21, 1891 – April 5, 1970) was an American geneticist. Sturtevant constructed the first genetic map of a chromosome in 1911. Throughout his career he worked on the organism ''Drosophila melanogaster'' with ...

and

H.J. Muller Hermann Joseph Muller (December 21, 1890 – April 5, 1967) was an American geneticist, educator, and Nobel laureate best known for his work on the physiological and genetic effects of radiation (mutagenesis), as well as his outspoken political ...

, Bridges was part of

Thomas Hunt Morgan Thomas Hunt Morgan (September 25, 1866 – December 4, 1945) was an American evolutionary biologist, geneticist, embryologist, and science author who won the Nobel Prize in Physiology or Medicine in 1933 for discoveries elucidating the role tha ...

's famous "Fly Room" at

Columbia University Columbia University (also known as Columbia, and officially as Columbia University in the City of New York) is a private research university in New York City. Established in 1754 as King's College on the grounds of Trinity Church in Manhatt ...

Early life

Calvin Blackman Bridges was born in Schuyler Falls,

New York New York most commonly refers to: * New York City, the most populous city in the United States, located in the state of New York * New York (state), a state in the northeastern United States New York may also refer to: Film and television * '' ...

in 1889 to the parents of Leonard Bridges and Charlotte Blackman. Tragically, Calvin's mother died when he was two years old, and his father died a year later, leaving the young Calvin an orphan. Bridges was subsequently taken in and raised by his grandmother. It took Bridges several years to complete high school, graduating when he was 20 years old. Despite this setback, he moved on to be an outstanding student at

New York City New York, often called New York City or NYC, is the List of United States cities by population, most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the L ...

, which he attended both undergraduate and postgraduate school. While taking a

zoology Zoology ()The pronunciation of zoology as is usually regarded as nonstandard, though it is not uncommon. is the branch of biology that studies the Animal, animal kingdom, including the anatomy, structure, embryology, evolution, Biological clas ...

class at Columbia, Bridges met

. This started a relationship which would eventually lead to many important scientific discoveries regarding genetics and

evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

Work and research

The "Fly Room" experiments began in 1910 and continued for seventeen years, with Thomas Hunt Morgan being the project's lead experimental developer."Bridges, Calvin Blackman." Complete Dictionary of Scientific Biography. Vol. 2. Detroit: Charles Scribner's Sons, 2008. 455-457. Gale Virtual Reference Library. Web. 28 Jan. 2015. Among many others working alongside Bridges and Morgan in the laboratory were

and

Hermann Joseph Muller Hermann Joseph Muller (December 21, 1890 – April 5, 1967) was an American geneticist, educator, and Nobel laureate best known for his work on the physiological and genetic effects of radiation (mutagenesis), as well as his outspoken political ...

. The "Fly Room" experiments were the first to use the common fruit fly ''

Drosophila melanogaster ''Drosophila melanogaster'' is a species of fly (the taxonomic order Diptera) in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the "vinegar fly" or "pomace fly". Starting with Ch ...

'' for research in genetics, because they are cheap, easily accessible, and reproduce quickly.Muhlrad, Paul J. "Fruit Fly: Drosophila." Genetics. Ed. Richard Robinson. Vol. 2. New York: Macmillan Reference USA, 2003. 42-45. Gale Virtual Reference Library. Web. 28 Jan. 2015. The experiments resulted in many important early discoveries in the field, resolved previously unclear issues such as the organization of genetic information within

chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...

s, chromosomal arrangement, and

linkage Linkage may refer to: * ''Linkage'' (album), by J-pop singer Mami Kawada, released in 2010 *Linkage (graph theory), the maximum min-degree of any of its subgraphs *Linkage (horse), an American Thoroughbred racehorse * Linkage (hierarchical cluster ...

sex chromosome A sex chromosome (also referred to as an allosome, heterotypical chromosome, gonosome, heterochromosome, or idiochromosome) is a chromosome that differs from an ordinary autosome in form, size, and behavior. The human sex chromosomes, a typical ...

s, and contributed to the emergence of modern treatments of genetics and

evolutionary biology 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 fo ...

from their classical foundations, all in an era before

molecular biology Molecular biology is the branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions. The study of chemical and physi ...

had yet revealed the structure or nature of DNA. The group also contributed to the understanding of the impact of

mutation In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mi ...

s on evolution in general. The success of the "Fly Room" experiments eventually made ''D. melanogaster'' a widely popular

model organism A model organism (often shortened to model) is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workin ...

for biological research of all types. Bridges in particular was responsible for many improvements regarding the techniques and the equipment used in the experiments. He suggested the use binocular microscopes instead of hand lenses that had been using before, which improved data quality and convenience. Bridges also developed temperature controls for the experiments which proved to be more useful and yielded better results than the previous temperature controls. Bridges published many works, one of his most famous being "Sex in Relation to Chromosomes and Genes". He also contributed many items to the ''Journal of Experimental Zoology'' and ''Science''. His work with sex-linked traits suggested that chromosomes contained

gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

s; Nettie Maria Stevens was later able to support this hypothesis by examining the chromosomes of the fruit flies. Bridges wrote a couple of papers presenting the proof. He thanked her as "Miss Stevens" without stating what her contribution was nor referring to her Ph.D. Bridges' PhD thesis on "

Non-disjunction Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly during cell division (mitosis/meiosis). There are three forms of nondisjunction: failure of a pair of homologous chromosomes to separate in meiosis ...

as proof of the chromosome theory of heredity" appeared as the first paper in the first issue of the journal ''Genetics'' in 1916. In this paper, he also established that the

Y chromosome The Y chromosome is one of two sex chromosomes (allosomes) in therian mammals, including humans, and many other animals. The other is the X chromosome. Y is normally the sex-determining chromosome in many species, since it is the presence or abse ...

does not determine gender in ''Drosophila''. Bridges' best-known contribution among ''Drosophila'' researchers is his observation and documentation of the

polytene chromosome Polytene chromosomes are large chromosomes which have thousands of DNA strands. They provide a high level of function in certain tissues such as salivary glands of insects. Polytene chromosomes were first reported by E.G.Balbiani in 1881. Pol ...

s found in larval

salivary gland The salivary glands in mammals are exocrine glands that produce saliva through a system of ducts. Humans have three paired major salivary glands (parotid, submandibular, and sublingual), as well as hundreds of minor salivary glands. Salivary gla ...

cells. The banding patterns of these chromosomes are still used as genetic landmarks even by contemporary researchers. Bridges was elected to the

National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, 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 Nati ...

in 1936 for his work with ''Drosophila''. After his death, Bridges' student Katherine Brehme Warren completed work on ''The Mutants of Drosophila melanogaster'' (1944), a classic book which was for two decades an indispensable resource for geneticists, with information from the "Red Book" later being transferred to the

FlyBase FlyBase is an online bioinformatics database and the primary repository of genetic and molecular data for the insect family Drosophilidae. For the most extensively studied species and model organism, ''Drosophila melanogaster'', a wide range of ...

database. Morgan and Sturtevant destroyed almost all of Bridges' notebooks after his death, except the four which were not in their possession.

Personal life

Bridges married Gertrude Ives, with whom he had four children. He was known to be both brilliant and very kind and considerate, though he was equally well-known for his womanizing and his struggles to keep up with family obligations. He was an atheist.H J Muller, 'Dr. Calvin B. Bridges', ''Nature'' 143, 191–192 (4 February 1939). In 1938, Bridges died from what is believed to have been a case of

syphilis Syphilis () is a sexually transmitted infection caused by the bacterium ''Treponema pallidum'' subspecies ''pallidum''. The signs and symptoms of syphilis vary depending in which of the four stages it presents (primary, secondary, latent, an ...

References

Sources

1. "Bridges, Calvin Blackman." ''Complete Dictionary of Scientific Biography''. Vol. 2. Detroit: Charles Scribner's Sons, 2008. 455-457. Gale Virtual Reference Library. Web. 26 January 2015. 2. Muhlrad, Paul J. "Fruit Fly: Drosophila." ''Genetics''. Ed. Richard Robinson. Vol. 2. New York: Macmillan Reference USA, 2003. 42-45. Gale Virtual Reference Library. Web. 26 January 2015. 3. "Bridges, Calvin Blackman." ''Britannica Biographies'' (2012): 1. Middle Search Plus. Web. 26 January 2015. 4. Gambis , Alexis, director. The Fly Room . Imaginal Disc, 2014.

External links

National Academy of Sciences Biographical Memoir
* * {{DEFAULTSORT:Bridges, Calvin 1889 births 1938 deaths American atheists American geneticists Columbia University alumni History of genetics People from Schuyler Falls, New York Scientists from New York (state)