A reversion to the bacterial world - bacterial DNA triggering ancient response mechanisms as a potential cause of cancer in humans.

Lateral gene transfer, also known as horizontal gene transfer, is a common occurrence within the bacterial world and is a less frequent, but nevertheless, an ongoing feature of the eukaryotic environment. Several studies, reviewed in this paper, have reported an increased likelihood of cancer in humans when there is a higher preponderance of bacterial lateral gene transferred material within the cell. Separately, it has been suggested that cancer in humans may be linked to an atavistic response to DNA damage in the cell by bacterially inherited DNA. It is proposed that a mechanism for cancer in humans is the triggering of ancient bacterially-derived response mechanisms by bacterial genetic material entering eukaryotic cells – a reversion to the bacterial world. The reversion to the bacterial world hypothesis can be tested by large scale and longitudinal sampling.