The first generation had reached grandparenthood at the time researchers enrolled them in the study. That meant people who had not lived long enough to become grandparents eliminated themselves from the study.
People who were infertile or who did not have children would also have been excluded as they would not have held grandparent status. The difference may or may not matter. Only more studies will tell.
Collecting the information involved some concrete information like death dates or birthdates for the last child born in a family. Still, for some aspects, the researchers relied upon memory. The grandmothers had to recall how old they were when they began puberty, for example. Families in the study were also genetically similar and living in one location. The environment has a significant impact on our physical health.
Despite these faults, what the researchers found falls in line with the current-favorite theory of aging, and the results were strikingly consistent. It has left my mind wandering—wandering toward the places where science can offer no answers.
How much will we want to know about our future, and could we meaningfully extend our lifespans? Will, we one day ask potential partners in life whether they expect an extended or shorter life? What if we find a way to slow the mutation rate dramatically? That might mean significantly increasing our lifespans.
What once were silly questions asked by children—Would you want to know how long you’ll live if you could look into a crystal ball?—have become the questions with which we may grapple someday soon.