“When females are born, they have a relatively low relatedness to the males in their group, because their father isn’t around,” Dr. Croft said. Advertisement Continue reading the main storyTo test their hypothesis, the researchers analyzed demographic data over 43 years for 200 whales. This unparalleled database of killer whales was an important strength of the study, said Ruth Esteban, who researches killer whales with Conservation, Information and Research on Cetaceans in Spain, and did not participate in this research. The scientists found that as younger females aged and had offspring, they indeed became more related to their pods. She believes the primary reason women live so long after menopause is because they help improve the survival of grandchildren, which helps pass their own genes on.

Source: New York Times January 12, 2017 17:00 UTC