Abstract
In this article, a proximate conception of parental investment for humans is developed. Parenting investment is introduced as a part of life histories, specifying the optimization of reproductive success in terms of inclusive fitness. Contextual, parental, and children's characteristics that influence investment decisions are specified. We can distinguish between four systems of parenting: primary care, body stimulation, body contact, and face-to-face interaction, which prompt different socialization experiences with different psychological consequences. Parental behaviors within these different systems may vary in terms of the expression of warmth and contingency. Parenting is described here as an intergenerational transmission mechanism of psychological characteristics as well as reproductive styles.