Killer whales are highly intelligent, socially organised – and the females are in charge. STEPHEN LEWIS speaks to a York scientist who has just returned from studying them.

IN the icy waters of the northern Pacific earlier this summer, York researcher Daniel Franks witnessed something remarkable.

He was spending a couple of weeks with the US Centre for Whale Research, observing killer whales off the coast of Washington State.

The whales live in 'pods' or extended groups of 30 to 40 animals, which comb the cold waters looking for food: usually salmon, in the case of these whales.

Dr Franks and other researchers had been going out in small boats to observe the whales close up, sometimes from only feet away.

But one day, they witnessed three separate pods of whales come together.

Two pods arrived first, then a third, larger one joined them. There must have been 80 or more of the animals altogether, Dr Franks says – and their behaviour was extraordinary.

"They started hitting the water with their tails, they were suddenly much more active. One came close to shore where I was and splashed me with water."

With his scientist's hat on, he would hesitate to say that they were happy to see each other, he says. "But there was certainly something going on. It did feel as though they were excited."

The thing about killer whales, says Dr Franks, is that they are highly social and highly intelligent. How intelligent, exactly? That's difficult to answer precisely, he says. "A whale would make a very stupid person. But then a person would make a very stupid whale."

They certainly live in complex social groups. The pod is the basic social unit, but within pods are smaller 'matrilineal' family groups organised around an older female. And there is even evidence that certain individual whales prefer to spend time with particular other whales – evidence of friendship perhaps, though that is not a word a scientist like Dr Franks would use.

The whales seem to communicate underwater with sophisticated whistles and calls – Canadian scientist John Ford has even identified distinct 'dialects', Dr Franks says – and they are capable of co-coordinating their movements, possibly when hunting. "They can move in flowing, close-knit groups, moving tightly together, like a moving herd or flock."

The females are hugely important within a killer whale social group, partly because they live so long – much longer than males. Males tend to live into their 40s.

"But females often live into their 90s. There's one female that we know of which is estimated to be over 100 years old."

With age comes great wisdom, goes the saying: and there is evidence that older females use the the knowledge and 'wisdom' they have gathered during the course of their long lives to help look after their family and their offspring.

"We're looking at whether they contribute in times of need by helping their family group find food," Dr Franks says.

It makes sense for them to do this in evolutionary terms, Dr Franks says, because many of the younger whales in a family group will be related to the oldest female. This is because throughout their lives, killer whales stay with their mother. A family group, therefore, is made up of the daughters and sons, granddaughters and grandsons of the oldest female, down to four or five generations.

Males go off to another family group to mate, but then they return to their mother's side afterwards and play no part in bringing up their own 'children'. In fact, they are 'mummies boys', sticking even closer to the side of their mother than their sisters do.

We know all this because scientists from the US Centre for Whale Research, where Dr Franks spent a couple of weeks over the summer, have been observing the Northern and Southern Resident populations of killers whales, which live in this area of the Pacific, for almost 40 years.

They have learned to identify individual whales from their 'saddle patch' – distinct patches on their back near the dorsal fin, which are as individual as human faces, Dr Franks says. And for decades, they have been recording the whales' movements, their social interactions – even their 'friendships'.

The data they have gathered has already revealed exactly how important older females are to their family. The children of female whales are much more likely to die once their mother dies. "In fact, the sons are more than ten times as likely to die within the next two years," Dr Franks says. It comes back to that wisdom of age. "The older individuals get, the more knowledge they acquire which they can use to help their offspring survive."

Now Dr Franks and a small group of fellow researchers from the University of York and from Exeter University have been awarded a £400,000 grant from the Natural Environment Research Council (NERC) to study another feature of this extraordinary species.

Killer whales are one of only three known species in which females go through the menopause. That means the females live on long after they cease to be able to have children.

Short-finned pilot whale females are also thought to go through the menopause. And the third species in which it happens is, of course, us – human beings.

In evolutionary, Darwinian terms, the menopause has always been something of a puzzle, Dr Franks says. Darwinian evolutionary theory (the classic 'battle for survival of the fittest') suggests that parents should have as many children as they can, because the more children you have, the more your genes will survive and spread in future generations.

So why, in these three species, do females live on past the age when they can have children? How does that help their genetic legacy to spread in the future? Aren't they just consuming food and other resources their children could have had?

There are several hypotheses to explain menopause, Dr Franks says: but the key ones come down to this. In long-lived, socially-complex species such as killer whales and humans it may be better to have fewer offspring and concentrate all your efforts on helping those few offspring to survive and flourish and have children of their own.

Because the more children you have, the less time and effort you can put into looking after each of them, and the lower each child's chances of surviving to grow and have children of its own.

According to this theory, killer whale females survive past the age at which they can have children because they can then continue to help their existing children. They use the knowledge and wisdom which comes with age to help these children grow to adulthood, and to have children of their own – and then help the grandchildren, too.

Dr Franks and his colleagues in York and Exeter will be analysing the 40 years of data gathered by the Centre for Whale Research – looking at the survival rates of children and grandchildren once their mothers/ grandmothers die – to see if they can prove this really is why killer whales go through the menopause.

His two week visit to the Pacific this summer to see the whales for himself was just to help him put the data he will be analysing into context: to get a 'feel' for the whales and their behaviour.

And what did he think of them?

For once, the 34-year-old allows his scientific mask to slip.

Being in a boat just a few feet away from the whales was awesome, he says. "They were right next to you. It was one of the best experiences of my life. They are amazing creatures."