Howard Temin was an American virologist known for his groundbreaking research on the replication of viruses. He was awarded the Nobel Prize in Physiology or Medicine in 1975 for his discovery of reverse transcriptase, an enzyme that allows certain viruses, like HIV, to convert their RNA into DNA. This discovery was crucial in understanding how retroviruses operate and how they can lead to diseases. Temin's work laid the foundation for further research in molecular biology and cancer. He was also a strong advocate for the ethical implications of scientific research and the responsible use of biotechnology. His contributions have had a lasting impact on both science and medicine.