Grandad

Grandparents are the parents of a person's own parent, whether that be a father or a mother. Every sexually-reproducing creature who is not a genetic chimera has a maximum of four genetic grandparents, eight genetic great-grandparents, sixteen genetic great-great-grandparents, etc. Rarely, such as in the case of sibling or half-sibling incest, these numbers are lower. In the history of modern humanity, around 30,000 years ago, the number of modern humans who lived to be grandparents began to skyrocket. It is not known for certain what spurred this increase in longevity. But it is believed that a key consequence of three generations being alive together was the facilitation of the passing along of information that prior to that point would have been lost; an example of this important information might have been where to find water in times of drought.