An international team of scientists has found the answer to why female killer whales have the longest menopause of any non-human species - to care for their adult sons.
The research led by the Universities of York and Exeter and published in the journal Science, shows 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.
The reason for the menopause remains one of nature’s great mysteries and very few species have a prolonged period of their lifespan when they no longer reproduce, as in humans.
However, female killer whales stop reproducing in their 30s-40s, but can survive into their 90s. While different theories have been put forward for the evolution of menopause in humans, including the well-established ‘grandmother’ hypothesis, there has been no definitive answer to why females of a small number of other species, including killer whales, also stop reproducing part-way through their lives.