Abstract:  This research integrates the life history theory and motivational theory of life-span development by exploring the intrinsic mechanism of life history trade-offs. Empirical work consists of two studies, both of which demonstrate the fact that control striving should be the intrinsic mechanism of life history trade-offs. Study One: 167 females and 63 males with a mean age of 26.6 years old (SD = 6.81) were measured with the inventories of Mini-K and Optimization in Primary and Secondary Control with the priming of “Recalling the important key events in your past life …” in instructions. The results showed that Optimization, Selective Primary Control (SPC) and Selective Secondary Control (SSC) statistically mediated the effect of childhood economic environment on life history trade-offs respectively, with Compensatory Primary Control (CPC) and Compensatory Secondary Control (CSC) showing the similar statistical tendency. Study Two: 36 females and 35 males with a mean age of 26.9 years old (SD = 3.42) attended experiments in study 2. Through a rigorous experimental design with the priming of mortality cues, results showed that Optimization significantly mediated the effect of the individual’s childhood economic status on delayed rewards under negative environmental condition.

Key words:  life history theory, life history trade-offs, intrinsic mechanism, control striving, mediating effect