Fig. 1.

Reproductive careers of mountain gorilla males. Thick dark bars indicate the dominant silverback, whereas thick light bars indicate the second-ranking male. Bars are hatched during periods when the dominance relationships were unknown. Thin bars span the ages of 7–12 years. Males below the age of 7 are indicated by dotted lines. The circles represent offspring and are each placed on the line of the assigned father at the estimated time of conception. Striped circles are untyped offspring. The one typed offspring for which paternity could not be assigned, although the dominant male was excluded, is indicated by a circled x. em, emigration out of the group.