Grandparenting has clear advantages in modern societies, producing benefits that affect social outcomes. The effect is such that Coall & Hertwig (C&H) propose a host of potential benefits, and some consequences, to be studied as a result of the influence of grandparenting. However, despite the sociological and economic effects of grandparenting studied today, there is little information regarding the evolution of grandparenting. Williams' (Reference Williams1957) assertion that early termination of fertility would be adaptive when maternal care is important to offspring survival, proposes that reproductive senescence is adaptive by enhancing the inclusive fitness of grandparents. While this premise has been modified several times in the past fifty years, all of the current hypotheses surrounding the evolution of grandparenting make the assumption that any feature, especially that which brings benefit to the family group, must be adaptive.

If it is adaptive, then menopause is a human autapomorphy. While it has been suggested that chimpanzees (Atsalis & Videan Reference Atsalis and Videan2009; Jones et al. Reference Jones, Walker, Anderson, Lacreuse, Robson and Hawkes2007) and gorillas (Atsalis & Margulis Reference Atsalis and Margulis2008) go through menopause if they live long enough, other studies (Cloutier et al. Reference Cloutier, Broadfield, Wolf and Halloran2009; Emery Thompson et al. Reference Emery Thompson, Jones, Pusey, Brewer-Marsden, Goodall, Marsden, Matsuzawa, Nishida, Reynolds, Sugiyama and Wrangham2007) suggest that menopause as it is applied to humans does not exist in chimpanzees. Chimpanzees fail to go through operational menopause, the cessation of menstrual cycling, as humans do. Indeed, chimpanzees have been recorded to have offspring well past the age of forty (Cloutier et al. Reference Cloutier, Broadfield, Wolf and Halloran2009). Although chimpanzee females may not spend their lives in the same group as offspring, most certainly spend years as grandmothers before daughters emigrate. However, there is no evidence that the grandmother's fecundity is reduced by the presence of their daughter's offspring. If one assumed that menopause should be adaptive and lead to the evolution of grandparenting, then it would seem likely that the trait should have evolved in our closest living relatives during their five million year history. However, this has not been the case, suggesting that menopause is a uniquely human character.

Adaptation assumes that a feature enhances fitness, and has the opportunity to be under selective pressure. While it has been argued that menopause is adaptive by protecting the individual from survival risks to herself or her potential offspring (Kuhle Reference Kuhle2007; Peccei Reference Peccei2001a), all of the hypotheses overlook the fact that menopause and life expectancy into postreproductive years are recent phenomena of human evolutionary history. Prior to 1900, there is little evidence to support menopause as a universal phenomenon in humans due to low life expectancy (see Christensen et al. Reference Christensen, Doblhammer, Rau and Vaupel2009). This suggests that prior to the 20th century menopause was not under selective pressure, as those individuals who lived into their post-menopausal years were few. As a result, the effect of living beyond reproductive years is a phenomenon that could have only recently come under selective pressure. However, it is unlikely that characters expressed in postreproductive years could be under selective pressure.

Current life expectancy projections for Europe and North America (Christensen et al. Reference Christensen, Doblhammer, Rau and Vaupel2009) suggests that humans can expect that almost half of their lives will be spent in postreproductive years. This could suggest that any benefit produced through a grandmother effect would be erased by the demands of offspring to care for grandparents. If maximum life expectancy were realized in humans, then the evolutionary costs could quickly outweigh the gains. However, in assuming that there is selective pressure on a postreproductive character, one has to assume that the character can be selected at all.

In the wild, few female chimpanzees survive past fifty (Hill et al. Reference Hill, Boesch, Goodall, Pusey, Williams and Wrangham2001), yet many become grandparents during their life. It is suggested that a similar life history was the norm throughout human evolution until recently (Caspari & Lee Reference Caspari and Lee2004). Indeed, it is only recently that both humans and chimpanzees have been found to live into either their postreproductive years (humans) or their pseudo-postreproductive years (chimpanzees). In the case of chimpanzees there is no current evidence of a cessation of menstrual cycling or a complete loss of fertility (Cloutier et al. Reference Cloutier, Broadfield, Wolf and Halloran2009; Emery Thompson et al. Reference Emery Thompson, Jones, Pusey, Brewer-Marsden, Goodall, Marsden, Matsuzawa, Nishida, Reynolds, Sugiyama and Wrangham2007), whereas in humans there is clear evidence that humans cease cycling after approximately fifty years of age. This disparity makes chimpanzees poor models for the evolutionary development of menopause.

Instead, menopause must be viewed in light of human evolutionary history alone. Although it can be argued that a postreproductive period enhances fitness by reducing the risks of reproduction on the mother and the offspring, it is unlikely that the postreproductive period can be viewed as adaptive for the function of grandmothering. Ellison (Reference Ellison2001) suggests that menopause could be an exapted feature of the depletion of a female's supply of oocytes. This implies, however, that oocyte depletion is adaptive. Although the quality of oocytes decreases in a female's lifetime, there is little to suggest that the feature should be selected. Again, there is little evidence suggesting a decline in the quality of oocytes in chimpanzees with age. If chimpanzees evolved the ability to continue to produce viable offspring to the end of their lives, then it would stand to reason that the same feature should be present in humans. That the feature is lacking in humans may not be a reflection of an adaptation to preserve oocyte quality, but instead could suggests that humans possess the feature as an epiphenomenon (Bogin & Smith Reference Bogin and Smith1996).

It is apparent that humans have benefited from relatives living into their postreproductive years. However, these benefits should not be viewed as adapted or selected, since their presence in human populations is recent. If menopause evolved to reduce the risks to the mother and offspring, then it should have evolved to begin at age 35, an age when the likelihood of risks to mother and offspring dramatically increase (Morris & Alberman Reference Morris and Alberman2009). In addition, there is little evidence to support the claim that there can be selection for a postreproductive period that would lead to grandparenting. More likely, grandparenting is a happy byproduct of other human characteristics, making it at best an epiphenomenon.