Co-evolution, as treated across the depth-psychology and cognitive-science corpus assembled in Seba, names a mutual, bidirectional process by which organisms and their environments — or, by extension, mind and world, culture and biology, self and other — constitute one another through sustained structural coupling rather than through a one-way impress of environment upon passive organism. The concept carries weight precisely where classical adaptationist accounts prove insufficient: it insists that neither pole of any evolving dyad pre-exists the relationship unchanged. Thompson, drawing on Maturana and Varela, makes this explicit in the enactive framework, where organism–environment co-determination displaces optimisation as the central evolutionary logic. Developmental Systems Theory, as Thompson presents it, extends the argument so that natural selection itself is reconceived as the outcome of differentially propagating developmental systems in which organism and environment ‘define and select each other.’ Damasio’s invocation of Durham’s work on genes, culture, and human diversity opens a complementary register: co-evolution operates not only between species and habitat but between biological imperatives and cultural formations. Hogenson situates the Baldwin Effect within this constellation, showing how learned behaviour can feed back into genomic change over evolutionary time — a dynamic relevant to Jung’s own thinking about the archetype. The term therefore bridges biology, phenomenology, and depth psychology, serving as a hinge concept wherever the corpus interrogates received nature-nurture dualisms.