Regeneration refers to biological processes through which structure or organisation is renewed or re-established following loss, damage, or disruption.
In conventional biological accounts, regeneration is often described in terms of the replacement of damaged or missing tissues, organs, appendages, or other structures. APS emphasises that structural replacement alone may not exhaust the biological explanation.
A regenerated structure may need to become integrated with other biological processes and relations relevant to the system concerned. Regeneration can therefore involve restoration or re-establishment of organisation as well as production of biological structure.
This does not mean that regeneration is defined by preservation of viability or organised persistence. Regenerative outcomes may be complete or incomplete, functional or dysfunctional, and their consequences for viability must be established for the biological case concerned.
Regeneration is often closely related to developmental organisation.
Regenerative processes may recruit capacities also involved in development, including cellular proliferation and differentiation, morphogenesis, signalling, pattern formation, physiological coordination, or other forms of developmental reorganisation. Which processes are required depends on the regenerative phenomenon being explained.
The explanatory extent of regeneration is likewise target-dependent. Some regenerative processes may be adequately explained through relatively local cellular or tissue relations, whereas others may require relations extending across wider spatial, temporal, physiological, developmental, or environmental extents. APS does not therefore assume that regeneration is intrinsically multiscale.
APS distinguishes regeneration from related concepts without imposing a universal taxonomy among them.
Regeneration and repair both concern biological restoration following damage or disruption, but their exact relation depends on the biological case and explanandum. Some processes may be clearly characterised as repair, others as regeneration, and some cases may involve overlapping restorative processes. APS does not define regeneration simply as broader, deeper, or more extensive repair.
Regeneration also differs from resilience. Resilience concerns capacities through which biological organisation withstands, accommodates, or recovers from perturbation. Regeneration may contribute to resilience where renewed production or re-establishment of structure or organisation supports recovery, but resilience need not depend on regeneration.
Regeneration can also intersect with adaptation and evolution, but these relations should not be inferred from regeneration itself. A regenerative capacity or outcome may have consequences for viability, fitness, selection, or evolutionary change in particular biological systems. Those relations require their own population-level and historical evidence.
Regeneration need not restore a perfectly identical prior state.
Regenerative processes may produce transformed organisation, altered developmental trajectories, compensatory restructuring, or modified functional integration. Whether such an outcome counts as successful restoration depends on the regenerative target and the biological organisation or function concerned.
Regeneration therefore illustrates an important feature of living organisation: biological systems can, in some circumstances, renew or re-establish organisation following substantial disruption. Where this contributes to viability or organised persistence, the explanatory relation should be demonstrated rather than built into the definition of regeneration.