If you are a faithful reader of the New York Times, you know about the “grandmother hypothesis.”

“When a young woman is burdened with a suckling infant and cannot fend for her family,” a New York Times reporter in 1997 noted about the Hadza people of north Tanzania, “she turns for support, not to her mate, but to a senior female relative — her mother, an aunt, an elder cousin. It is Grandma, or Grandma-proxy, who keeps the woman’s other children in baobab and berries, Grandma who keeps them alive.”