From the mid-thirties onwards, Martin Heidegger occasionally speculated about the future possibility of artificially producing human beings. What is at stake in biotechnology, Heidegger claims, is the imminent possibility of the destruction of the human essence. It is unclear, however, how Heidegger can substantiate such a claim given that he consistently denounced attempts to define human Dasein as a living being to which a higher capacity such as reason or language is added. This paper will argue that, in this sense, (...) Heidegger took the radical challenge of biotechnology both too seriously and not seriously enough. Too seriously, because it is unclear why he would fear the annihilation of Dasein’s essence if he is convinced that this essence is not related to man’s biological equipment in the first place. Not seriously enough, because Heidegger at the same time remained convinced that even the most intrusive interventions in the human body will not be able to disrupt Dasein’s ontological essence. (shrink)