MATRIARCHAL SOCIETY - THE WISDOM OF MENOPAUSE ORCAS HELP SURVIVE THE YOUNGER
Classic life-history theory predicts that menopause should not occur because there should be no selection for survival after the cessation of reproduction. Yet, human females routinely live 30 years after they have stopped reproducing. Only two other species—orcas (Orcinus orca) and short-finned pilot whales (Globicephala macrorhynchus) — have comparable postreproductive lifespans. In theory, menopause can evolve via inclusive fitness benefits, but the mechanisms by which postreproductive females help their kin remain enigmatic. however, a study about orca behavior, published in Current Biology, suggests that older females provide valuable information for the survival of the group. According to the study’s authors, female orca, who are mothers between 12 and 40 years can get to fulfill 90. But, What is the evolutionary point of living so long without being able to reproduce? Until now it was known that the longevity of mothers increases the chances of survival of their sons. According to the authors, females led their groups especially in times of shortage of salmon. Information on how and where to find fish, it can be vital for survive. The wisdom they bring older females “may help explain why female orca and women continue to live long after they have ceased to reproduce,” said Brent, who lead the study
Photo: A postreproductively aged female, J16, leads her adult son and two adult daughters. credit: Dave Ellifrit, Center for Whale Research.
Reference: Brent et al. 2015. Ecological Knowledge, Leadership, and the Evolution of Menopause in Killer Whales. Cell