In 1999, there were around sixteen staff writers working on "The Simpsons". Many of them had written for the show for several years, including John Swartzwelder and George Meyer. The third episode of the tenth season, "Bart the Mother", was the last full-length episode written by David S. Cohen, a longtime writer on the show. He left to team up with "The Simpsons" creator Matt Groening to develop "Futurama", a series on which he served as executive producer and head writer. The tenth season marked the full-time return of staff member Al Jean, who had departed from the show after the fourth season to create the animated series "The Critic". Between seasons four and ten, he had only worked periodically on the show, writing four episodes.