[1] Born in Washington, DC, Jack Harlan was the son of Harry Harlan, a plant breeder who worked on barley at the US Department of Agriculture (USDA), and who travelled around the world on seed collecting expeditions in search of new genetic material for use the USDA's crop breeding programs.
This meeting inspired Jack to become a plant collector himself, and plans were made for him to travel to Russia after finishing his undergraduate degree to work with Vavilov.
He went on to study under the famous botanist and geneticist G. Ledyard Stebbins at the University of California, where he received a Ph.D. in genetics in 1942.
[5][6] As a scientist Harlan had two complementary research interests; the practical work of breeding economically important crops for desirable traits such as disease resistance or higher yield, and archaeobotany, the archeological study of the origins of crop domestication.
[8] Harlan agreed broadly with Vavilov's idea that just a few geographical locations are crucial for generating much of the biodiversity on which plant breeders depend.
There were many independent tentatives in many locations that fused over time to produce effective food production systems.