In other words, gene swapping. From The Scientist , June 20:
“It really does seem that human genome sequence data from somatic cells show signs of LGT events from bacteria, and so do cancer cells,” said Jonathan Eisen from University of California, Davis, who coordinated the peer review of the new study but was not involved in the work. “Wild stuff does happen.”
“LGT is incredibly important in evolution but many claims of specific cases of LGT have been seriously flawed,” said Eisen. “I came into this as a serious skeptic. It just seemed so improbable.”
But the team won him over. They ran an extensive set of checks to make sure that these bacterial sequences were not laboratory artifacts and had not come from contaminating microbes.
If lateral (horizontal) gene transfer turns out to be an important factor in evolution, as is increasingly likely (it has already been identified in plants and animals), it could raise merry hay with Darwinian attempts to postdict the history of life using Darwin’s natural selection alone.