Morphogenesis — the generation of form — is one of the central problems in biology and one of its most direct connections to relational thinking. How does a fertilized egg, a single cell, become a structured organism with differentiated tissues, organs, and body plans? The standard molecular account attributes form to genetic programs: DNA encodes instructions, and development executes them. But this account faces a persistent difficulty. The genome specifies proteins, not shapes. The gap between molecular components and macroscopic form requires an account of how relational organization emerges from local interactions.
D’Arcy Wentworth Thompson’s On Growth and Form (1917) proposed that biological form is governed by physical forces — surface tension, diffusion gradients, mechanical stress — as much as by hereditary factors. Thompson showed that the shapes of organisms could be related to one another by continuous mathematical transformations, suggesting that form is a product of the field of forces acting on growing tissue rather than a blueprint read out from a genome.
Alan Turing’s reaction-diffusion model (1952) formalized one mechanism: two chemicals diffusing at different rates can spontaneously generate spatial patterns — stripes, spots, waves — from an initially homogeneous field. The pattern isn’t encoded anywhere; it emerges from the dynamics of the system. This is a concrete instance of metastability resolving into form: the homogeneous field is metastable, and the reaction-diffusion dynamics drive it toward a patterned equilibrium.
Fungal growth provides a particularly tractable system for studying morphogenesis. A mycelial network generates its form through continuous hyphal tip extension, branching, and fusion (anastomosis). Branching decisions respond to local chemical gradients — nutrient concentrations, oxygen levels, signals from other organisms — and the resulting network topology emerges from these distributed local interactions without any central plan. The chitin deposited in hyphal walls couples molecular synthesis to macroscopic form: wall composition determines rigidity, flexibility, and growth direction. The mycelial network is morphogenesis made visible as an ongoing process rather than a developmental endpoint — the form is never finished, continuously extending, pruning, and reorganizing in response to its environment.
The implications for relationality are direct. If biological form emerges from field dynamics rather than encoded instructions, then the organism is not a substance that has properties but a process that constitutes itself through the relations among its components and the physical fields they inhabit. Parts do not precede the whole; they are individuated by the morphogenetic process that generates the whole. This is mereology in action: the whole is not the sum of preexisting parts but the relational process that makes the parts what they are.
Related concepts
- Mereology — the part-whole relations that morphogenesis instantiates
- Metastability — the condition of charged equilibrium from which biological form resolves
- Autopoiesis — self-producing organization as the ongoing maintenance of morphogenetic outcomes
- Combinatorial Scent Mereology — another biological domain where mereological composition structures perception
- Mycelial Networks — morphogenesis as ongoing network formation through branching, growth, and anastomosis