Howard Temin was a Jewish American geneticist who was awarded the 1975 Nobel Prize in Medicine.

Temin (born December 10, 1934; died February 9, 1994) was born in Philadelphia, Pennsylvannia. He received his bachelor's degree in Biology from Swarthmore College in 1955 and his doctorate from the California Institute of Technology in 1959. In 1960, Temin became an Assistant Professor at the University of Wisconsin-Madison, in the McArdle Laboratory for Cancer Research. Over the years, he has held various position at the university including Associate Professor, Full Professor, Wisconsin Alumni Research Foundation Professor of Cancer Research, and American Cancer Society Professor of Viral Oncology and Cell Biology (1974).

He discovered reverse transcriptase in the 1970's at the University of Wisconsin-Madison. He won a Nobel Prize in Physiology or Medicine in 1975, along with David Baltimore and Renato Dulbecco, for describing how tumor viruses act on the genetical material of the cell through reverse transcriptase. This upset the widely held belief at the time of the "Central Dogma" of molecular biology posited by Nobel laureate Francis Crick, one of the co-discoverers of the structure of DNA (along with James Watson and Rosalind Franklin). Crick, along with most other molecular biologists of the day, believed genetic information to flow exclusively from DNA to RNA to protein. Temin showed that certain tumor viruses carried the enzymatic ability to reverse the flow of information from RNA back to DNA using reverse transcriptase. The discovery of reverse transcriptase is one of the most important of the modern era of medicine, as reverse transcriptase is the central enzyme in several widespread human diseases, such as HIV, the virus that causes AIDS, and Hepatitis B. Reverse transcriptase is also an important component of several important techniques in molecular biology and diagnostic medicine, such as the polymerase chain reaction (PCR).

A long-time advocate against smoking, Temin died at the age of 59, on February 9, 1994, from lung cancer, although he himself was never a smoker.

The following press release from the Royal Swedish Academy of Sciences describes Temin's work:

The fact that the viruses can cause tumours was shown already more than 60 years ago by Rous in studies of sarcomas and leukemias in chickens. However this observation was for a long time regarded as a biological curiosity and not until during the 1950ies was it shown that under certain conditions viruses could cause leukemias and other tumours also in other animals, e.g. mice. Studies of virus-induced changes of the growth characteristics of a normal cell to that of tumour cells - a phenomenon referred to as transformation - was facilitated during this decade due to the availability of methods for cultivating cells under laboratory conditions. This technique combined with the discovery of several viruses which could cause transformation in animals and in cell cultures provided facilities for studies of the role of the virus in this process. It was found that both viruses which contain genetic material of the same type as that present in chromosomes of cells i.e. deoxyribonucleic acid (DNA) and also viruses containing a different type of genetic material, ribonucleic acid (RNA) could cause transformation.

Sources: Wikipedia, Nobelprize.org, Nobel Prize Autobiography