Of monkeys and men: Spitz and Harlow on the consequences of maternal deprivation.

In this contribution the reciprocal influence of Harlow and Spitz concerning the consequences of maternal deprivation of monkeys and men, respectively, is described. On the basis of recently disclosed correspondence between Harlow and Spitz, it is argued that not only was Spitz's work on hospitalism an inspiration for Harlow to start his cloth and wire surrogate work with rhesus monkeys but, at the same time, Harlow's work was a new impetus for Spitz's work on the sexual development of (deprived) infants. It is described how the two men first established personal contact in the early 1960s, after Harlow had published his first surrogate papers, how they became close friends subsequently, and inspired each other mutually.