This applies to hunger, fear and most of psychology including perception. Organisms have not been designed to simply maintain energy, repair tissues and outlive others but rather selection has designed them to replicate their genes through the somewhat risky endeavors of sexual reproduction and parental investment. Parental Motivation and discriminative solicitude Parenting is a very important aspect of the behavioral repertoires of many species, including people. Most women have been known to devote most of their time in nurturing and caring for their offspring. Hence, offspring have become the vehicles of parental fitness.
Parental investment can occur in a variety of ways.
For example, they can provide food and protection for their offspring. When a parent doubts that the offspring is indeed their own, it reduces the amount of parental fitness payoffs. Among several siblings, parental investment may differ between the younger and smaller offspring in relation to the older siblings. This may occur because of the certainty of parenthood, whether the offspring maintains any reproductive value or simply the fitness value of the available alternatives. The product of the reproductive value of an offspring and its relatedness to the parent determines the offspring s expected contribution to parental fitness.