Revealed: Why killer whales go through the menopause

Researchers from Exeter University joined an international research team, looking at why killer whales go through the menopause.

Killer whales are one of only three known species of mammal, including humans, to go through the 'change of change'. Their studies conclude that a 'mother daughter conflict' can explain why they stop reproducing.

The study builds on research showing that post reproductive killer whales have a ‘grandmother’ role within the pod and that they share knowledge of when and where to find food which increases the survival of their family group.

Professor Croft joined scientists from Cambridge and York University, as well as from the Center for Whale Research in the USA and Fisheries and Oceans Canada. Together, they studied two populations of killer whales which live off the North West Pacific Coast of Canada and the US.

Both sons and daughters stay with their mothers and don’t disperse, but they mate with individuals from a different family group. Males typically have a shorter lifespan than females - many not surviving beyond 30 years. Female killer whales, usually stop reproducing in their 30s-40s but just like humans they can live for many decades following menopause.

The bottom line, Croft says, is that menopause is no accident. Rather, it’s an evolved trait driven by both cooperation and conflict in family groups. The findings help to explain factors that are driving the whales’ survival and reproductive success, which is essential information given that the Southern Resident killer whales - one of the whale populations under study - is listed as endangered and at risk of extinction.

Professor Croft and the research team are planning to use drones in the next phase of research to study the killer whales behaviour more closely, including a more in-depth analysis of the conflicts between mothers and their daughters.

Watch Andrea Bishop's full report

Pictures courtesy: Centre for Whale Research