"Genesis" is the 171st episode of the American science fiction television series Star Trek: The Next Generation and the 19th episode of the seventh season. It was directed by series cast member Gates McFadden, her only directing credit to date. Set in the 24th century, the series follows the adventures of the Starfleet crew of the Federation starship Enterprise-D. In this episode, Captain Jean-Luc Picard and Data return to the USS Enterprise to discover the rest of the crew de-evolved into primitive forms of life, including spiders, amphibians and cave men. This episode was broadcast on March 21, 1994. Plot Picard and Data leave the Enterprise in a shuttlecraft to retrieve a photon torpedo that has veered off course during a weapons exercise. Before departing, Data leaves his pregnant cat, Spot, with Lieutenant Barclay. Convinced that he is suffering from a devastating illness, the hypochondriac Barclay visits Dr. Crusher, who diagnoses a mild case of the flu and injects him with a synthetic T-cell to activate one of his dormant genes that confers immunity. Shortly afterward, crew members begin to experience strange symptoms; Counselor Troi feels cold and develops an uncontrollable thirst, while Riker has trouble concentrating and Barclay becomes fidgety and overly energetic. Worf feels hot and becomes aggressive, trying to stay near Troi and eventually biting her on the cheek. Both are taken to sickbay for treatment; when Crusher examines Worf and finds a venom sac growing on his neck, he spits acidic poison in her face. A severely injured Crusher is placed in stasis, while Worf escapes. Nurse Ogawa warns the senior staff that everyone on the ship is in danger. Picard and Data return after three days, having retrieved the wayward torpedo, but find the ship adrift and its main power offline. One of the bridge officers is dead, torn open in his seat, and most of the crew are de-evolving. Troi has reverted into an amphibian; Riker an Australopithecine (Caveman); and Barclay a spider. Data discovers that a synthetic T-cell has invaded the crew members' genetic code and activated their introns at random, causing them to de-evolve. Picard is soon overcome by irrational emotions of fear and anxiety, indicating that he has been infected, and Data suggests he might soon become a primate similar to a lemur or marmoset. Picard and Data return to Data's quarters and find Spot and her kittens. Spot herself has