Killer whales are "mummy's boys"

Posted on 14 September 2012

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....