Scientists in the UK have published a study that may reveal the reasons why females orcas can live for a further 50 years after having their offspring.
According to experts from the University of Exeter, the presence of mothers ensured greater survival of adult sons to an age when they can breed, and so might explain possible reasons for this long but non-reproductive phase of their lives.
Orcas have one of the longest post-reproductive life spans in the natural world and the young never leave their mothers, remaining in a single group or pod.
The research showed that, for a male over 30, the death of his mother means an almost 14-fold-increase in the likelihood of his death within the following year.