Doctor Skelpa was a Gelezen who sought to replenish her people's human DNA pool with fresh samples extracted from Martha Jones, having tracked her on Earth to Liverpool in 1963. Her DNA had been enhanced because of her experiences travelling in time with the Tenth Doctor and potentially offered the clone-race the opportunity to live forever. Martha was ultimately responsible for destroying the time-field that protected the planet from outsiders and helped ensure their thousands of years of self-imposed isolation. When the planet's barrier was destroyed, the Doctor freely offered a sample of his own DNA, which saved the Gelezens from becoming extinct and gave them new life. (COMIC: Signs of Life)