Killer whale moms may do this by assisting with foraging, providing support during fights and through other means.
Human mothers obviously live in a different societal structure, so caring for sons, daughters, and their grandkids may hold equal importance, at least from an evolutionary standpoint.
Such caregiving might even help to explain why menopause exists in the first place.
"While it is believed that menopause evolved in humans partly to allow women to focus on providing support for their grandchildren, it seems that female killer whales act as lifelong carers for their own offspring, particularly for their adult sons," Croft said. "It is just incredible that these sons stick by their mothers' sides their entire lives."
Michael Cant, an associate professor in evolution and animal behavior at the University of Exeter, Cornwall, told Discovery News, "This new data offers an exciting new insight into the evolutionary puzzle of menopause."
He pointed out that the issue has been difficult to study because, outside of humans and killer whales, only one other mammal -- the pilot whale -- goes through menopause. Whales are inherently difficult to study.