Only three mammal in the world are experience to go through change of life . Alongside mankind , there are suddenly - break water pilot whales and killer hulk in something of a motley bunch . The uniqueness of this stage of life has puzzled scientist for quite some fourth dimension . Now , however , the mystery of menopause , at least for the orca , may have been solved .
There are mountain of mammals in which the older females become the leader of the group , such as with elephants , and impart their cognition to the younger extremity , often consisting of their offspring . But while matriarchal elephants continue breeding throughout their entire lives , matriarchal orcas stop .
A team of researchers have find that the old female whales may stop reproducing in a bidding to trim back competition between her calfskin and those of her grownup daughter . By looking at over 43 class ’ Charles Frederick Worth of information collected from two population of killer giant dwell off the North West coast of Canada , they found that the older mothers have a much higher cost than their daughter – to the extent that the deathrate of the old mothers ' issue was 1.7 fourth dimension that of the younger mother .
“ Our old work show how old females assistant but not why they discontinue reproducing , ” says Professor Darren Croft , who led the report bring out inCurrent Biology , in astatement . “ female of many species act as leaders in late liveliness but continue to reproduce , but this new research shows that onetime female go through the menopause because they misplace out in procreative rival with their own daughters . ”
So rather than investing in more issue that are more likely to die , the older female instead stop reproducing and concentrate on providing for their grandchild and the seedpod as a whole . This also link up into another curious behavior of the whales , where mothers will still touch in food sharing , give up salmon they catch to other members of the pod .
The older female are vital for the survival of the pod not only because they feed other member , but because they have full of life entropy that younger whales will not yet know . If there has been a high-risk year in salmon , for exemplar , the older killer whale whales may know where to go for a more reliable rootage .
“ Our unexampled workplace shows that if an old female slayer giant multiply her late - sprightliness issue suffer from being out - competed by her grandchildren,”explainsco - generator Dr Daniel Franks . “ This , together with her investment in helping her grandchildren , can excuse the evolution of menopause . ”
