Data Sheet 1_Heterochrony as temporal redistribution of developmental burden.pdf

It does not necessarily presuppose a conserved resource, nor does it necessarily entail the transfer of energetic or material resources. Progenesis illustrates this distinction: reproductive maturity is attained earlier relative to somatic development and is represented as an earlier developmental endpoint, thereby redistributing burden in time without necessarily involving resource transfer. This separates changes in developmental organization from the stronger hypothesis of resource-linked allocation or trade-offs, which requires independent evidence.

It also distinguishes instantaneous from cumulative burden and somatic development from reproductive maturation, preserving the biological differences among canonical heterochronic modes. The formalism generates testable expectations: prolonged development may reduce instantaneous burden while extending cumulative commitment, early termination may truncate somatic burden, and subsystem prioritization should produce temporally asymmetric growth or maturation profiles.

Applications to amphibian paedomorphosis, human neural development, hominin evolution, dinosaur ontogeny, and bat limb development demonstrate its scope. The equations serve as formal organizing relations for comparative hypothesis development rather than as a parameterized predictive model. By connecting classical heterochronic categories with measurable growth, metabolic, and maturation data, the framework provides a common language for investigating how developmental timing, subsystem organization, and energetic feasibility jointly shape morphological evolution.</p>