On phenotypic variation and Waddington's Landscape

Waddington's landscape for embryonic development invites us to consider the dynamical constraints shaping the entirety of organismal development. While Francis Crick envisioned the marble rolling down the landscape as a metaphor for a differentiating cell, Conrad Waddington instead saw the marble as representing the embryo as a whole—capturing the emergence of its physico-chemical form. Within this framework, what then constitutes the alternative basins of attraction? What defines the axes of the landscape? And how does time emerge from the dynamics themselves? Through a sequence of three of our studies, along with a review of Waddington's experiments on genetic assimilation, I will explore the open questions that remain and why addressing them is crucial for advancing our understanding of how developmental programs constrain evolution—and, conversely, how evolution shapes development.