- Person
- Carl Djerassi
- Lived
- 1923–2015
- Field
- Chemistry
- From
- Austrian-American
The story
By the 1960s Carl Djerassi, who had helped create the contraceptive pill at Syntex in Mexico City, was a professor of chemistry at Stanford University and a world authority on working out the structures of complex molecules such as steroids and alkaloids. Identifying an unknown compound was slow, expert work that depended on interpreting data from instruments such as mass spectrometers, a field in which Djerassi was a pioneer.
At the same time the Nobel laureate geneticist Joshua Lederberg was helping design instruments for NASA's Viking lander to search the Martian soil for the building blocks of life, using a mass spectrometer linked to a small computer. He wanted a program that could reason about what such data meant. Beginning in the mid-1960s, Lederberg, the computer scientist Edward Feigenbaum, Bruce Buchanan and Djerassi, with a team of research associates and students, built DENDRAL, short for dendritic algorithm. Written in the Lisp programming language, it was designed to deduce the molecular structure of unknown organic compounds from their mass spectra and a body of chemical knowledge.
Early versions struggled with some classes of compounds, so Djerassi taught the program general rules of mass spectrometry and chemistry that let it discard chemically implausible structures, and he extended it to use data from nuclear magnetic resonance. A companion program, Meta-DENDRAL, tried to learn new rules from examples. By 1970 DENDRAL was interpreting structures at the level of a postdoctoral chemist, and Djerassi's group used it in their own research for a decade.
DENDRAL is considered the first expert system, a program that captures the knowledge of human specialists, and one of the first uses of artificial intelligence in biomedical research. Many later systems were derived from it, including MYCIN, MOLGEN, PROSPECTOR and XCON. Its approach, combining a large knowledge base with rules of thumb to narrow a vast number of possibilities, shaped decades of research in the field.
Djerassi's chemical expertise supplied much of the knowledge the program encoded. Today software that suggests structures from mass spectra is routine in chemistry laboratories.
Why it matters
DENDRAL helped launch the expert-system approach that shaped decades of artificial-intelligence research in medicine, chemistry and beyond.
About Carl Djerassi
Refugee from Nazi Vienna whose Syntex team in Mexico City first made norethindrone, a key oral contraceptive; later a novelist and playwright.
More about Carl Djerassi
- Carl Djerassi made cortisone from a Mexican yamIn 1951 Carl Djerassi's team at Syntex in Mexico City synthesised cortisone from a compound in a wild yam, using a cheaper raw material and about half as many steps.
- Carl Djerassi helped create an early antihistamineAs a 19-year-old chemist at CIBA in New Jersey in 1942–43, Carl Djerassi helped develop Pyribenzamine, one of the first commercial antihistamines and his first patent.
- Carl Djerassi published more than 1,200 scientific papersCarl Djerassi pioneered the use of mass spectrometry and optical rotatory dispersion to decode the structures of steroids and alkaloids, publishing more than 1,200 papers.
- Carl Djerassi pioneered gentler insect controlIn 1968 Carl Djerassi founded Zoecon to control pests with modified insect hormones instead of broad poisons, work honoured with the US National Medal of Technology in 1991.
- Two chemists wrote the play Oxygen togetherIn 1999 Carl Djerassi and the Nobel chemist Roald Hoffmann co-wrote Oxygen, a play about the discovery of oxygen and about what it means to be a scientist.
- Carl Djerassi gave his Paul Klee collection to museumsCarl Djerassi assembled one of the most significant private collections of Paul Klee's art and arranged for it to go to the Albertina in Vienna and SFMOMA in San Francisco.
- Carl Djerassi turned his ranch into a haven for artistsAfter his daughter Pamela, an artist, died in 1978, Carl Djerassi turned his California cattle ranch into the Djerassi Resident Artists Program, a retreat for working artists.
- Carl Djerassi invented science-in-fictionStarting with Cantor's Dilemma in 1989, Carl Djerassi wrote novels in a genre he called science-in-fiction, showing readers how real scientists think, compete and behave.
- Carl Djerassi helped create the first oral contraceptiveIn 1951 Carl Djerassi, a refugee from Nazi Austria, co-invented norethisterone in Mexico City, the first highly active progestin that worked by mouth and a key ingredient of the Pill.
Sources
- Carl Djerassi Wikipedia
- Dendral Wikipedia
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