More menopausal species discovered
BELUGA WHALES and narwhals are the latest species which scientists have discovered go through the menopause.
The findings of a new study, by researchers from the University of Exeter, University of York and Center for Whale Research, means five species are now known to stop reproducing and continue living.
Along with humans, killer whales and short-finned pilot whales were the only others previously known to experience the menopause. Most species continue reproducing until they die. The study, in journal Scientific Reports, used data from the dead whales of 16 species and found dormant ovaries in older beluga and narwhal females.
These species may have social structures which mean females live among more and more close relatives as they age.
They suggest that menopause has evolved independently in three toothed whale species, with beluga whales and narwhals sharing a common ancestor.
Dr Sam Ellis, from the University of Exeter, said: “For menopause to make sense in evolutionary terms, a species needs both a reason to stop reproducing and a reason to live on afterwards. In killer whales, the reason to stop comes because both male and female offspring stay with their mothers for life – so as a female ages, her group contains more and more of her children and grandchildren.”