It is probably one of the most peculiar aspects of human biology - that females of a certain age lose the ability to reproduce . Now scientists have discovered that killer whales - a species separated from humans by almost 94 million years of evolution - also suffer from the menopause and it could provide clues as to why it evolved in the first place . There is just one other species in the wild known to undergo the menopause - short-finned pilot whales - although it has been observed in a handful of captive primates and animals . Older female killer whales tend to take the lead ( like the one above ) when families are foraging for food . The evolution of a trait that reduces the reproductive capability of a species has long baffled biologists and there are a number of theories for why it emerged in humans . Now a team of researchers from the University of Exeter and the University of York may have unraveled the reason for the menopause - in killer whales at least . It happens to every woman who reaches a certain age , but in the animal kingdom , the menopause is a relatively uncommon trait . Humans can live long after they stop being able to reproduce , but most animals tend to remain fertile up until they die . A few species of primate , like rhesus monkeys , orangutans and chimpanzees are also known to experience menopause while it has also been reported in elephants and short-finned pilot whales . Laboratory rats , captive opossums and budgerigars have also been observed to under go the menopause . However , the short-finned pilot whale and the killer whale are the only animals that been been seen to live long past the age that they lose the ability to reproduce . They have found that it frees up the older , more experienced females to lead their families in the search for food and so boost the ability of the entire group to survive . The findings may now also help to explain why the menopause emerged in human populations - it allowed older women to impart their knowledge and help care for the younger members . Professor Darren Croft , a behavioural ecologist at the University of Exeter , said : 'In humans , it has been suggested that menopause is simply an artifact of modern medicine and improved living conditions . 'However , mounting evidence suggests that menopause in humans is adaptive . 'In hunter-gatherers , one way that menopausal women help their relatives , and thus increase the transmission of their own genes , is by sharing food . 'Menopausal women may also have shared another key commodity - information . ' The researchers , whose study is published in the journal Current Biology , studied groups of killer whales in the wild off the coast of British Columbia and Washington during nine summer salmon migrations . Female killer whales can continue having calves , like above , until around the age of 35 years old say scientists . In total they observed 102 whales - 58 of which were female - and studied which of the whales occupied the lead position as the whales hunted for the salmon . They also used 35 years worth of data on the whale population in the area to identify those that had gone through the menopause . On average female killer whales older than 35 years old were found to have gone through the menopause . The researchers found that the older post-reproductive females tended to lead groups of the whales when they were foraging for salmon . Orca are one of just two species that are known to undergo the menopause in the wild other than humans . They were also more likely to take the lead in years when the salmon abundance was low - meaning the killer whales were struggling to find food . This is because the older females are using their greater experience to help the group find food , say the researchers . Dr Lauren Brent , a behavioural biologist at the University of Exeter who was the lead author of the research , said : Our results show that postreproductive females may boost the fitness of kin through the transfer of ecological knowledge . 'The value gained from the wisdom of elders can help explain why female killer whales and humans continue to live long after they have stopped reproducing . The researchers also found that post-menopausal killer whales were also more likely to lead their sons than their daughters . Dr Daniel Franks , from the University of York , said : 'Killer whale mothers direct more help toward sons than daughters because sons offer greater potential benefits for her to pass on her genes . 'Sons have a higher reproductive potential and they mate outside the group , thus their offspring are born into another gruop and do not compete for resources within the mother 's matriline . '
Killer whales are 102 of a handful of animals that undergo the menopause . Short-finned pilot whales and killer whales are the only wild species whose females are known to lose the ability to reproduce as they age , like humans . Killer whales go through the menopause at an average age of 35 years old . Post-reproductive females tend to lead groups when hunting for salmon . They are more likely to lead during lean times when salmon are hard to find . Scientists at the University of Exeter say the older females are imparting their knowledge and experience for the benefit of the rest of their family . It may help to explain why the menopause evolved in older human women .