If you’re lucky enough to have spent an afternoon being taken care of by a grandmother or grandfather when you were little, you know the importance of grandparents in the family.
A new study from researchers at Emory University in Atlanta has detailed the impact of grandparents and concluded they play an integral role in helping humans live longer.
Their research helps explain why humans, unlike many other animals, have relatively long childhoods and also live well past their peak reproductive years.
The study, published by the Royal Society B, looked at the foraging Tsimane people of Bolivia and the relationship between generations when it came to sharing food.
Food is a universal sign of love. Think of anytime cookies or candy have been offered as a sign of caring, or the feeling you get when sitting down at the table for a dinner together with family.
For the Tsimane, an indigenous people in the Amazon reliant on hunting and foraging, researchers concluded the sharing of food is no different. Food sharing across generations was found to be key in helping individuals survive and flourish.
Researchers measured the net flow of calories between individuals and across generations.
"The results support the theory that grandparents are key to our relatively long childhood and long lifespan, which are a big part of what makes us human,” said study leader Paul Hooper, Ph.D., an anthropology professor at Emory University, in a news release. “Their efforts have likely been underwriting human society for hundreds of thousands of years."
The study concluded parents gave the most food to children. Grandparents, however, were second, followed by uncles, aunts, and children over the age of 12.
"Our data gives a clear picture of how the life history of our species is supported by high surplus food production in older age and the redistribution of that surplus to younger kin," Hooper said.
Between 2005 and 2010, researchers collected data through fieldwork with Tsimane forager-horticulturalists under the Tsimane Health and Life History Project.
About twice a week, production and sharing interviews were conducted with 239 families in eight villages. For every food product produced, researchers recorded who consumed the food, what was given as a gift, and so on.
Researchers analyzed the data and mapped the transfers of food between children, grandchildren, spouses, and children-in-law from parents, grandparents, and parents-in-law.
"Beyond showing that food resources flowed from older to younger generations, we were able to predict how much each person gave to each other, based on their relative productivity and the closeness of their relationship," Hooper said.
The greatest net transfer of food to grandchildren occured around age 10. It was strong in the first two decades of life. When parents were not alive or didn’t live in the same community, grandparents gave more food to grandchildren, the researchers found.
Daughters received a significant amount of food from their parents until their mid-20s, while young men were estimated to provide upward transfers of food to their parents. Mothers benefited after the age of 60, when they become recipients of food from children.
For the Tsimane, food largely comes from growing cassava, plantains, rice, and corn, foraging for plants, and fishing and hunting animals like deer, tapirs, monkeys, and capybaras.
“Tsimane grandparents are helpful because they are skilled and competent in areas that require years of experience,” Hooper told Healthline. “In our families, we can do better by recognizing and capitalizing on the different strengths offered by each member of the family.”