The Epigenetic Ceiling: Why DNA Alone Cannot Decode Ancient Human Adaptation
The study of human evolution has long been anchored in the sequence of the four chemical bases—adenine, guanine, cytosine, and thymine—that constitute our genetic code. By comparing the DNA of modern humans with that of archaic hominins like Neanderthals and Denisovans, scientists have successfully mapped migrations, interbreeding events, and the selection of specific alleles. However, a significant hurdle remains in understanding "deep time" adaptation: DNA tells us what a creature could have been, but it does not tell us how that creature actually lived or responded to its environment. This is the realm of epigenetics, and the stark difference in the preservation of DNA versus epigenetic markers creates a profound "information gap" in our understanding of ancient phenotypic adaptation. The Preservation Paradox The core of the issue lies in the biochemical stability of the molecules involved. DNA is a remarkably resilient double-helix structure. Under ideal conditi...