The Influence of Children on Late Life Mortality in Humans
Researchers here examine mortality data from one of the wealthier parts of the world, where more people have chosen not to have children, and thus there is a large enough data set to make useful comparisons between older people with and without children. The researchers show that having children adds a few years to life expectancy, conforming to similar past results. The demographic data offers little when it comes to support for any one possible mechanism over others, but some of the options are discussed in the paper. The primary focus is on increased support from children, financial and otherwise, once the parents have entered the frail and vulnerable final stage of aging.
It is well established that parents live longer than non-parents, but the underlying mechanisms are unclear and it is not known how the association changes over the life course. In Sweden and the other Nordic countries, there is an overall trend of increasing levels of childlessness across birth cohorts. It may therefore be valuable to improve our understanding of how childlessness is linked to health and survival chances in old age. We hypothesise that support from adult children to their ageing parents may be of importance for parental health and longevity.
However, there are of course several alternative explanations. For example, the timing and number of children could affect the mortality risk of women through biological pathways. Still, a protective effect of parenthood has been found for mothers and fathers, which may suggest that the biological mechanisms that apply to women is not the only explanation to the association, and other factors matter as well. One such factor could be various types of support from adult children to their ageing parents, such as informational, emotional and social support. In addition, parents have on average more healthful behaviours than childless individuals. It is also possible that the survival advantage of parents over non-parents is due to confounding from biological or social factors influencing the chances of having children and the risk of death. Health-related selection may be important at any phase during the life course, but it seems reasonable that the influence would not increase when parents become very old, but rather being more significant before average life expectancy (LE) as frailer individuals tend to die off. The need for social support from family members may, on the other hand, increase when parents age because ill health becomes more common with increasing age and the ability of self-care may decrease.
How the mortality advantage of parents over non-parents changes over the life span is not known. Previous studies have mainly examined associations between parity and subsequent mortality from 40 years of age up to around 60 years of age. This study closely examines the association between parenthood and longevity, with specific focus on the strength of the association in old age, and with absolute and relative measures. More specifically, we investigate; (1) the association between having a child alive in old age and the risks of death among Swedish men and women, (2) whether the association increases with age of the parent and (3) whether the association persists when stratifying for marital status (taking into account the possible confounding effect of having a partner cohabiting).
This study found an inverse association between having a child and death risks in old age, and, importantly, that the death risk differences between parents and non-parents increased with age of the parent, among men and women. Further, the differences in death risks between individuals with and without children were somewhat larger for men than for women. Our finding that the association grew stronger when parents became older is further in agreement with research suggesting that childless people face support deficits only towards the end of life. However, selective elements and alternative explanations, for example, that parents have more healthy behaviours than non-parents, are not ruled out. The association between having children and mortality persisted when stratifying for marital status, taking into account the possible confounding effect of having a partner. Two of our findings may be interpreted as working against the hypothesis about the importance of social support in older ages: the lack of a stronger mortality association for parents whose children lived fairly close, and the insignificant results for the gender of the child.
It seems that all of the proposed mechanisms point toward the conclusion that humans are designed for long term strong social bonding. This benefits both parent and child.
Cultural bias.
Non-parents from this age group would have been either - people with high risk lifestyles or people with high intensity jobs. By definition they always die younger.
Parents with children living closest had high mortality if you had bothered to read the article to the end, which points to the inverse conclusion - people were never "designed" for the constant annoyance children can exert on their senior parents. But it's nice to have someone check on you once in a while and help you get to the hospital when you're crashing. Day to day help seems to be irrelevant - except for latest life - bedridden people cannot survive on their own, what a surprise.
There is no genetic mechanism at work. What is at work here is culture and quite honestly obvious facts of life any geriatrician can learn after a single year on the job.
It seems probable to me that more robust and intelligent people are both more likely to reproduce and live longer. I do not see how a study can control for that.