Prof. Yaacov Lorch was born in Breslau, Germany and grew up in Nurnberg in an educated and well to do family. The family left Germany to escape the rise of Nazi regime in 1935 and immigrated to Palestine.
Yaacov joined the Department of Botany at the Hebrew University in 1952 as an Assistant and was promoted to Lecturer in 1963. He initially focused on palynology (the study of fossil plant pollen) and paleo-climatology. Later he turned mostly to studying the history of science and was also a member of the Department of History and Philosophy of Science. When the biology departments were consolidated into the Institute of Life Sciences in Givat Ram, Yaacov joined the new Department of Ecology, Systematics and Evolution (ESE), where he remained until his retirement in the early 1990s.
Following his retirement he worked on a thorough research project documenting science education in Germany throughout the rise of Nazism, following the shift in the curriculum to political indoctrination rather than science.

Following his retirement, Yaacov coordinated the ESE undergraduate seminars  and the departmental seminar. When he coordinated the departmental seminar he invited a broad range of speakers, not necessarily within the research fields of the department, but of general interest to everyone.
Yaacov was characterized by very broad knowledge and a wide range of interests, and this allowed him to carry on witty conversations on almost any topic.
David Shohami remembers: "he was one of the most interesting and witty persons I have met during my time in the department, and it was always a pleasure bumping into him in the hallway and hearing about his latest philosophical thoughts."