The folklore of parenthood tells us that if we have children and invest the requisite time, money and love, we can avoid a life of loneliness in our old age. But having children is no guarantee.

Census data show that approximately 85 percent of American women over the age of 50 have children. And yet 43 percent of older people feel lonely, according to a study by researchers at the University of California, San Francisco. Some call loneliness a public health crisis; others say it poses a greater threat than obesity. Research shows that among older adults, loneliness is a predictor of functional decline and death.

We are finally beginning to understand that just as it takes a village to raise a child, it takes a village to shepherd people through their golden years. For some, that village may include adult children. In 2015, the Pew Research Center found that 58 percent of Americans with parents over 65 help them with errands and other chores.

But we shouldn’t assume that adult children will always be available to care for an aging population, especially as the number of older Americans without children or other family on whom they can rely grows. A 2015 report by the AARP predicts a steep decline in the ratio of potential family caregivers — those age 45 to 64 — to people 80 years old and beyond. In 2015, there were 6.8 potential family caregivers for every person 80 and older; by 2050 that ratio is expected to fall to less than 3 to 1.