It is not known for certain what spurred this increase in longevity, but it is generally believed that a key consequence of three generations being alive together was the preservation of information which could otherwise have been lost an example of this important information might have been where to find water in times of drought. In the history of modern humanity, around 30,000 years ago, the number of modern humans who lived to be a grandparent increased. Every sexually-reproducing living organism who is not a genetic chimera has a maximum of four genetic grandparents, eight genetic great-grandparents, sixteen genetic great-great-grandparents, thirty-two genetic great-great-great-grandparents, sixty-four genetic great-great-great-great grandparents, etc.
Grandparents, individually known as grandmother and grandfather, are the parents of a person's father or mother – paternal or maternal. The Favorite – Grandfather and Grandson, by Georgios Jakobides (1890) For other uses, see Grandfather (disambiguation), Grandmother (disambiguation), Grandma (disambiguation), Grandpa (disambiguation), Granddad (disambiguation), Gramps or Gramp, Abuelo, Abuela, and Grandaddy.
