Apoptosis reveals human evolutionary heritage sequestered in non-coding DNA

Cell-free chromatin particles (cfChPs), primarily derived from non-coding DNA (ncDNA) and released from apoptotic cells into the bloodstream, can be horizontally transferred into living cells ¹ . However, their potential role in generating ncDNA within recipient cells remains unknown. We previously reported that cfChP-sized fragments generated upon sonication of high-molecular-weight DNA can indiscriminately transmit themselves into foreign cells across species and kingdom boundaries ² . We hypothesised that cfChP-like DNA–protein complexes generated following organismal death are exchanged among species and progressively accumulate to form a dense patchwork that constitutes ncDNA, and that apoptosis may dissociate these complexes and render them amenable to detection. To test this hypothesis, we used species-specific DNA fluorescent in situ hybridisation probes and antibodies against archaea, eubacteria, plants, algae, fungi, protozoa, Drosophila, fish, chicken, mouse, rat, pig, dog and monkey on intact and apoptotic human cells. We observed no reactivity with intact cells but strong reactivity with the ncDNA component of apoptotic cells. Our findings indicate that ncDNA represents a dense conglomeration of interspecies DNA–protein complexes that become detectable following apoptosis. These results suggest that human evolutionary heritage resides within ncDNA, transmitted horizontally through apoptotic processes.