Two factors led to the creation of three new forms of the epact in the Fifteenth and Sixteenth centuries. The first was the increasing error of computistical techniques, which led to the introduction of a new Julian epact around 1478, to be used for practical computations of the phase of the Moon for medical or astrological purposes. With the Gregorian reform of the calendar in 1582, two additional epacts came into use. The first was the Lillian epact, developed by Aloisius Lilius as an element of the ecclesiastical computations using the Gregorian calendar. The Lillian epact included corrections for the motions of the Sun and the Moon that broke the fixed relationship between the epact and the golden number. The second new epact was a simple adjustment of the practical Julian epact to account for the ten-day change produced by the Gregorian Calendar. 
Koko was born in the San Francisco Zoo in 1971 and spent the first six months of her life in the nursery of the children’s zoo behind a glass window where the public could see her and where Penny Patterson, then a Stanford graduate student, met her. From age six months to one year Koko was critically ill and moved to a trailer on zoo property. Penny began working with Koko when she recovered her health, and requested permission from the zoo to continue working with her as part of her . research in psychology at Stanford University. The zoo agreed as long as Penny agreed to make at least a "4-year" commitment.