Killer whales may have menopause so grandma can look after the kids

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Posted on October 17, 2013
Killer whale

Killer whales are just one of three species – we’re one of the others – that continue to live long after they’ve stopped reproducing. But scientists still don’t know why these three alone evolved this unusual menopausal trait.

In a bid to find out, NERC has agreed to fund a project worth nearly £500k to look at why killer whales stop reproducing a third of the way through their lives, dedicating the rest of their lives to protecting and caring for children and grandchildren.

The researchers suspect that the menopause, which the whales experience in their 30s or 40s, is related to the animals’ social structure.

“Killer whales have a very unusual social system whereby sons and daughters don’t disperse from their social group but instead live with their mother her entire life. As a female ages she shares more genes with group members, and theory predicts that older females can benefit more from helping their offspring and grand offspring than reproducing themselves,” says Dr Darren Croft of the University of Exeter a lead investigator on the study.

“The situation with killer whales is quite different to humans. When a killer whale couple reproduces, the male will go to another group to mate with a female there. But, unlike the human population, he will later return to the group where his mother is. So in whales we have different ideas for why older females maybe have more pressure to look after their offspring, and grand-offspring,” says Dr Dan Franks of the University of York a lead investigator on the study.

Read more at: Phys.org