The standard hierarchy of developmental biology runs from genes to cells to tissues to organisms. Gene regulatory networks specify cell fates; signaling molecules guide differentiation; transcription factors activate the right programs at the right time. Physics — mechanical forces, tissue stiffness, fluid pressure — enters as a downstream consequence. The genome orchestrates; mechanics obeys.
Cofre (arXiv:2603.18293) inverts the hierarchy. Totipotency — the ability of a single cell to generate an entire organism — is proposed as a persistent mechanical memory: a biomechanical record preserved through morphogenesis. The zygote's totipotent nature is not specified by its genome but revealed by its physics. Mechanical forces are the primary information carriers, and the genetic program is downstream of the physical state.
The evidence thread runs from embryology through cancer. Embryonic cells differentiate along mechanical gradients — stiffness, compression, shear — before the relevant transcription factors are even expressed. Cancer cells that revert to an undifferentiated state show altered mechanical properties first, gene expression changes second. The preneural state — the developmental stage that gives rise to the nervous system — emerges not from a genetic switch but from mechanical boundary conditions that select for neural tissue properties.
The evolutionary implication is provocative: the animal nervous system arose because mechanical pressures during development created a niche for cells specialized in responding to mechanical stimuli. Neurons are the evolutionary product of mechanics selecting for mechanical sensitivity. The first nervous system was a mechanical feedback loop that became self-reinforcing.
If correct, totipotency is not a program that runs but a physical state that persists — a mechanical record that development reads rather than writes. The genome provides the vocabulary. Physics writes the sentence.
Cofre, "Mechanical cues for totipotency and the preneural state: embryo and cancer expanding the frontiers of developmental physics," arXiv:2603.18293 (2026).