Coall & Hertwig (C&H) discuss the changing role of grandparents in industrialized societies and the scarcity of research on grandparental investment in low-risk families. They develop a comprehensive model that generates novel hypotheses regarding the psychological mechanisms underlying grandparental investments. Particularly, they emphasize the benefits of moving beyond classic fitness indices and including psychological outcomes. Taking a lifespan developmental perspective, we offer additional reasons for focusing on grandparental investment as a key resource that may promote the harmonization of work and family responsibilities in low-risk families, thereby enhancing the developmental outcomes of children and grandchildren.

Past research shows beneficial effects of grandparents on the health and survival of grandchildren in historical or contemporary agricultural societies. It is an open question whether and how these benefits extend to today's industrialized societies. Evidence from high-risk families suggests that grandparents constitute a protective resource for their grandchildren. Little is known, however, about low-risk families. This research gap needs to be filled for at least two reasons. First, many low-risk families struggle to meet increasing demands at work and at home. For instance, employers expect increasing flexibility and mobility of employees (Klumb & Gemmiti, in press), while institutional childcare is rigid and not always available. The demands of juggling work and family life can negatively impact the health and well-being of parents and children alike (Strazdins et al. Reference Strazdins, Clements, Korda, Broom and D'Souza2006). Research on low-risk families will thus enable us to identify factors that enhance health and well-being in large segments of the population. Secondly, in some European countries, the increased demands of juggling work and family life have coincided with dramatic decreases in fertility. In Germany, for example, childlessness increases with education and is highest among university graduates (Duschek & Wirth Reference Duschek and Wirth2005). In other countries, too, women's careers come at a cost to their private lives (Galinsky et al. Reference Galinsky, Salmond, Bond, Kropf, Moore and Harrington2003). Reversing such demographic trends is difficult, but seems possible (Myrskylä et al. Reference Myrskylä, Kohler and Billari2009). Grandparental support may be one important piece in this picture. By supporting working parents, grandparents can serve as buffers against the negative consequences of parental stress on children, and, in regions with scarce childcare facilities, they may be an important factor in women's decisions to have children (Hank & Kreyenfeld Reference Hank and Kreyenfeld2003). Hence, there may be an important indirect pathway through which grandparental investment benefits grandchildren, namely, by alleviating stress in the middle generation. Further investigation of this pathway seems promising, because, as C&H point out, the overlap between the lives of grandparents and grandchildren is currently at its peak.

C&H develop intriguing hypotheses regarding the role of psychological mechanisms (e.g., empathy) in motivating grandparental investments. We would like to offer an additional perspective on the antecedents and consequences of grandparental investments by introducing the concept of developmental tasks to the discussion (Erikson Reference Erikson1966). The concept of developmental tasks represents a system of age-related, socially valued themes (Havighurst Reference Havighurst1953). Generativity is a key task in the second half of the adult lifespan and is characterized by a sense of responsibility for subsequent generations, in particular a concern to guide the next generation (Erikson Reference Erikson1966). Generativity is strongest with respect to one's own offspring and may thus be an important motivator for grandparental investments. For example, by participating in the care of grandchildren, grandparents may be able to help their adult children to reconcile their work and family responsibilities while contributing to the raising and guiding of their grandchildren. The literature also proposes that the realization of developmental tasks fosters personal growth and well-being. This suggestion is supported by observations that adult children's attainments and achievements are central for the well-being of older parents (Ryff et al. Reference Ryff, Lee, Essex and Schmutte1994). Hence, generativity may serve not only as an important motivator of grandparental investment benefiting younger generations, but also as a source of well-being for grandparents themselves. We would like to illustrate possible mechanisms by drawing on data from a recent study on the pursuit of work and family goals in employed parents with preschool children (Hoppmann & Klumb Reference Hoppmann and Klumb2004; Reference Hoppmann and Klumb2006). The study asked 84 highly educated employed parents in Berlin to report their work and family goals, rate time- and strategy-based conflicts between their goals, and indicate access to grandparental childcare. In addition, we recruited 31 of the grandparents who provided childcare and asked them to complete the Loyola Generativity Scale and to report their own goals, their respect for their adult children's goals, and affect quality. As the Berlin metropolitan area has a good childcare infrastructure, none of the grandparents were daily caregivers. Findings indicate that grandparental generativity, goals related to wanting to leave an imprint on others' lives and wanting to feel needed, and respect for adult children's goals were positively associated with grandparents' desire to provide childcare. These associations held when we controlled for living distance, grandparental employment status, health, and age. Hence, generativity seems to be an important motivator of grandparental investments. In addition, we found that grandparental childcare provision and adult children's pursuit of work and family goals were positively related to grandparental positive affect. Hence, grandparental investments and adult children's achievements seemed to be important sources of well-being in this sample. Finally, we examined the impact of grandparental childcare on their adult children. We found that grandparental childcare buffered the negative effects of adult children's goal conflicts upon their pursuit of work and family goals. This finding suggests that grandparental investments may indeed be a key resource facilitating the harmonization of work and family lives in adult children.

Future research on the buffering effects of grandparental investments should differentiate the needs created by different types of stressors. Grandparental support may be most effective when it matches those needs (Cohen & Wills Reference Cohen and Wills1985). For example, grandparental childcare may help employed parents struggling against time scarcity, but it may not work as well if employed parents are emotionally challenged (Frone Reference Frone2000). Furthermore, there may be circumstances in which grandparental support is a mixed blessing. Although grandparents may be a powerful resource capable of offsetting stress in younger generations, lifespan research shows that unasked-for support can be perceived as a suggestion of incompetence and thus a threat to the self (Smith & Goodnow Reference Smith and Goodnow1999). Hence, grandparental support may convey mixed messages that can strain relationships with children. We would therefore like to emphasize the importance of determining the specific conditions under which grandparental investments are beneficial for all concerned.