 The widow finally gives in and eventually establishes a regular training program for the "groups" making the trip back in time to ensure they have the basics for survival and a trade in the Pliocene era.To prevent any contamination of the past, the Galactic Milieu sterilises all females by salpingectomy before allowing them to go back to the past and does not allow any advanced technology that will not decompose after around a hundred years to be taken.The Milieu also does not allow any operant metapsychics to go back to the Pliocene.