The Epigenetic Ceiling: Deep Time and the Limits of Ancestral Reconstruction
The standard narrative of evolutionary biology relies heavily on the stability of DNA. By sequencing the genomes of extant species and comparing them to ancient DNA (aDNA) recovered from specimens up to a million years old, researchers construct phylogenetic trees that trace the "descent with modification" of all life. However, a significant tension exists in this methodology: DNA provides the blueprint, but it does not account for the immediate, adaptive "scaffolding" provided by the epigenome. If phenotypic plasticity—the ability of an organism to change its physical traits in response to the environment—is driven by epigenetic tags that degrade far faster than the DNA sequence itself, our window into the true adaptive history of life is severely lopsided. The Preservation Gap The fundamental challenge in confirming common ancestry through a holistic biological lens—incorporating both genotype and phenotype—is the disparate "half-life" of bio...