ABSTRACT
The obviousness of reproduction and parenting derives from one simple fact: it is the most straightforward way for individuals to enhance their evolutionary success, or—more to the point—for genes to project copies of themselves into the future. Among many birds—especially the most abundant order, the Passerines or perching birds, which includes the common songsters such as robins, sparrows and warblers—males and females cooperate in rearing the young dividing their parenting chores pretty much equally. Step-parenting is a darker and more troubled phenomenon. It is similar to adoption, in that no genetic "parents" end up taking care of someone else's children. But step-parenting is crucially different. Whereas adoption involves a specific commitment to the adopted child, step-parenting typically comes about as a side-effect of two adults' commitment toward each other. The equivalent of adoption and step-parenting does occur, although not frequently.
