Male killer whales real "Mama's sons", which, even as adults, they can not live without parent care. Therefore, orcas, ceased reproductive age, continue for a long time to take care of their tender sons.

Female killer whale watch over their sons almost all my life. (Photo Corey Ford.)

Animal life cycle is usually determined by the ability to procreate: when the individual leaves of reproductive age, she dies. The situation is quite different - man: woman after menopause can live more than a dozen years, taking care of children, grandchildren and great-grandchildren. Some researchers directly assert that menopause in humans evolved under the pressure of evolution that a woman can continue to take care of already born children, grandchildren and so on (Though there are other variants of answers.)

As for the person, that this point of view is still waiting for the correct and strict proofs. But in the case of dolphins, killer whales this hypothesis can be regarded as fully proven.

Not only the person has menopause: same physiological adjustment probably happen with females of two groups of cetaceans - whales and Blackfish. For example, killer whales can live to be 90 years old, although their reproductive age ends in the 30-40 year life. It is also known that these cetaceans combined in complex social groups, in which the female lives side by side with their children.

Researchers from the University of Exeter (UK) since the 1970s watched Pacific killer whales, conducting statistics of births and deaths among them. By 2010, this chronicle covered almost six hundred individuals. And, as it turned out, the early death of his mother affects the survival of its offspring, even if that seed has long been independently. However, it concerns only males.

According to zoologists in the journal Science, mortality among young males were doubled, and among those who were 30 years and more - in eight times (!) compared to "families", which was a DOE is a mother. Young females suffered the death of a parent, without any serious consequences, and only in adult females mortality increased 2.7 times, which is not equal to those of males.

It becomes clear why the female killer whales live so long, even after leaving reproductive age. They help to survive their adult sons. And this is why the adult males remain "Mama's sons", zoologists can't say; any attempt to explain it stumbles upon a lack of information about the social life of these animals. Monitoring of cetaceans in the natural environment is not the most simple and cheap lesson, so, obviously, it will be a long time before we learn about the reasons of such sensitivity orphaned male killer whales.

Based on the materials of Exeter University.