- It has been argued that suicide relates to a diminished residual capacity to promote inclusive fitness, defined as the welfare and reproduction of self and kin. The present study examined whether this relationship is reflected in suicidal and subsuicidal ideation in the general population. A questionnaire concerning parameters of inclusive fitness, suicidal ideation and experience, and attitudes toward the value of life was distributed to samples of the general public and university undergraduates. Analyses indicated significant moderate relationships between inclusive fitness and suicidal ideation in both samples. Among items most strongly related to reported suicidal ideation were expectations of poor future health, perceptions of being burdensome, and unstable heterosexual relationships, with importance of other factors depending on age.