How Does Life Unfold? A Landscape Metaphor Comes Into Its Own.

In the 1940s, British biologist Conrad Hal Waddington proposed a metaphor to explain how cells in an embryo specialize into different types, such as skin or nerve cells.

He visualized this process as a rolling landscape with hills and valleys, where a ball representing a stem cell rolls downhill.

The valleys represent the final cell types, and the branching points show where cells choose their fate.

Waddington called this metaphor the epigenetic landscape, and it suggested that cells are guided by the landscape's shape, much like water flowing through river valleys.

This idea was groundbreaking because it framed development as a dynamic process shaped by interactions, not just a simple readout of genes.