Tom was a male sim purchased by Samuel Pepys in 1661. Tom and a female, Peg, became domestic servants in the Pepys household. While watching Tom and Peg, Pepys developed the transformational theory of life. This set Pepys to thinking further, along with his observations of a shimpanse in the London menagerie. The animal was more bestial than a sim and yet more human than any other animal. This indicated to Pepys that there was a more gradual variation between humans and other animals than one would first consider.