[Temporal layers of the clone. Remarks on a conceptual history]

This paper aims at a history of the clone concept in 20th-century life science and culture. The first part of the paper is concerned with conceptual history approaches. Here, the idea of 'Zeitschichten' by Reinhart Koselleck is discussed and its implications for the history of science are explored. In the following parts of the paper, I trace the historical dynamics of the clone concept in various fields of 20th-century life sciences. I argue that the clone concept, which originated in plant breeding around 1900, soon developed into a technical tool in a variety of research areas. With this, specific meanings became attached: the idea of standardization, genetic identity, and mass reproduction. A further connotation of the clone was the idea of stagnancy with respect to processes in time: The clone was seen as something that was exempt from evolutionary changes. In the last section of the paper, I trace the shifting meanings of the clone concept in the 1960s and 1970s, when the clone became a widespread metaphor that pointed to future biotechnologically driven possibilities to reshape the nature of human beings. In this regard, the debates of the 1970s are analyzed as a turning point: Whereas utopian and eugenic visions predominated the debates in the 1960s (when the human clone was seen as something which will occur in a distant future), the 1970s discussion focused on the advent of a biotechnological era and the human clone had became a reality.