Paper short abstract:

The exclusive focus on genetics has obscured an alternate path to thinking the human and the posthuman, namely that offered by embryology. In the 20th century, embryology was an immensely compelling field for both theorists and experimental scientists attempting to rework the boundaries of the human.

Paper long abstract:

When it comes to defining the human in the 21st century, genetics is usually taken to be the key to understanding the material basis of our species, as headlines about Neanderthal DNA in Europeans and Asians attest. In this paper, I argue that the exclusive focus on genetics has obscured an alternate path to thinking the human and the posthuman, namely that offered by embryology. In the 20th century, embryology was an immensely compelling field for both theorists and experimental scientists attempting to rework the boundaries of the human. I offer two examples. The first is Raymond Ruyer, a philosopher who gained detailed knowledge of embryogenesis and teratology during the Second World War and used this knowledge to develop a non-humanist metaphysics. The second is the contemporary biophysicist Henri Atlan, who writes embryology into the history of complexity, ultimately arguing that it is not the concept of "human" but the concept of life itself that has become irrelevant in the 21st century.