Through a series of excursions into the historical archives of Human-Computer Interaction (HCI), this text aims to excavate the disciplinary roots of posthuman scholarship. By doing so, a lineage is outlined of how this philosophical strand first emerged in descriptions of people's relationships to and interactions with new technology. Drawing from cybernetics, ecological psychology, and people-centred approaches, interaction design evolved from these entangled understandings of real-world practice. A conclusion is that the contemporary turn to posthumanism does not reflect a radical departure from, but rather a return to our field's own foundational commitments. Ultimately, this is positioned as a theoretical homecoming that reorients HCI toward relational, situated, and ecologically responsible design.