De-extinction: how reviving the past is revolutionizing the future of conservation biology.

Human activity is driving a biodiversity crisis marked not only by accelerating species extinctions but also by rapid erosion of genetic and phylogenetic diversity. De-extinction science has emerged in response. Here, we synthesize de-extinction as a conservation workflow that integrates ancient and museum genomics, comparative genome analysis, high-precision genome engineering, stem cell platforms, advanced assisted reproductive technologies (ART), emerging ex-utero gestation systems, and AI-enabled ecological modelling and monitoring. We frame three primary conservation applications: (i) reconstruction of lost ecological functions via engineered de-extinct species, (ii) genetic rescue and de-endangerment through restoration of lost diversity, repair of deleterious alleles, and enhancement of adaptive potential in living species, and (iii) acceleration of enabling technologies, particularly ART and stem cell capabilities, that remove reproductive bottlenecks in threatened taxa. Recent advances in sequencing and assembly now support high-quality genomes from extinct and archival material (e.g., thylacine, mammoth, dodo), enabling identification of functionally relevant variation, much of which resides in regulatory landscapes rather than coding sequence alone. In parallel, next-generation editing systems (base, prime, twinPE and large-fragment integration approaches) are shifting the field from single-variant correction to systematic rewriting of loci and regulatory modules, supported by long-read validation and stringent cell-line quality control. We discuss complementary cellular routes (somatic cells and pluripotent stem cells), the promise of in vitro gametogenesis and synthetic embryo models, and the potential of artificial gestation to overcome surrogate scarcity and interspecies incompatibility. Finally, we highlight rewilding as the decisive endpoint, requiring adaptive management, Indigenous partnership, and high-fidelity AI-assisted monitoring. Taken together, de-extinction is best understood as a technology engine for conservation, one that expands the actionable toolkit for preventing extinctions, restoring resilience, and rebuilding lost biodiversity.