91av

Hal Whitehead is Killam Professor of Biology at Dalhousie University in Halifax, Nova Scotia. He studied mathematics at the University of Cambridge before turning to marine biology. He prefers to be at sea on his yacht, studying the behaviour, ecology and population biology of sperm whales and northern bottlenose whales. Their social organisation and cultural transmission of behaviours is his consuming interest. His latest book, Sperm Whales: Social evolution in the ocean, is published by the University of Chicago Press.

How do you go about studying sperm whales?

It is not easy. They spend almost all their lives deep in the ocean, where they are invisible to us. There is so much we don’t know about them.

I prefer to stick to simple technologies. I like to spend my time out at sea among the animals, collecting lots of data then trying to make sense of it.

One thing we are about to try out is recording with an array of hydrophones. That will enable us to work out where each sound is coming from and so where each whale is in the group. But for it to work the whales have to be virtually within the array. This is difficult because sperm whales are always on the move, so we have developed model boats to carry the hydrophones to allow us to keep abreast of the whales.

You started in mathematics. How did you get from there to whales?

When I got my degree I didn’t want to spend the rest of my life as a mathematician. I wasn’t sure what I wanted to do, so I travelled for about a year. Then I bought a boat and started sailing here on the Nova Scotia coast. I started seeing whales, met some whale biologists, and one thing led to another.

Mathematics is an advantage in studying whales. You have to figure out how to analyse the data. Often the peripheral skills are very significant.

How much of your life do you spend at sea?

On average I’m at sea for six weeks a year. It used to be a lot longer but now I have children. The children sometimes come too, but they find the whales boring. They’ve been going out with whales most of their lives. When we see whales everyone goes frantic and no one pays attention to the kids. I met my wife, marine biologist Linda Weilgart, through my whale research. We work together now, though in recent years she has been concentrating on conservation issues, especially how underwater noise affects whales.

I love it at sea. I really like being out there in what is about as near as we can get to true wilderness, a habitat with very little obvious human influence.

Does it get lonely?

It doesn’t bother me being away from most humans. Usually there are five of us on the boat when we’re doing research, and we’re living at pretty close quarters with each other. If you have a good crew it can be a wonderful working environment. If you have a poor crew and you’re the only one keeping the thing going then it can get a little lonely.

You swim with the whales. What is that like?

When you’re underwater with them it’s extraordinary. They are a mixture of things you can identify with, and things that are utterly alien to us, all wrapped up in one animal. You see an eye following you, or you see them tending to their young. These kinds of things we can associate with. Yet there are a whole lot of aspects which are strange, especially when they dive down to a place where we can’t go without a submarine. We still don’t know much about what they do down there.

We snorkel with them because they are either at the surface or 400 metres down, so there’s no point being in diving gear.

One of the things that happens when you’re swimming with them is they will echolocate off you. You hear – feel, really – these enormously powerful clicks running through your body. That is quite something.

Do you feel like there’s communication?

It’s communication in the sense that both you and the whale are getting information about each other. Probably the whale is getting more than you, because echolocation is more powerful than vision in water. And I’m less in my right mind than the whale is at that time, so it’s getting a clearer view of me than I am of it.

It’s like coming across someone from a totally different culture, an ancient living culture that you know almost nothing about – and they know nothing about your culture. You are communicating, but at a fairly primitive level. But it can be mind-blowing: the idea of something so large and powerful that also may have all the social and cognitive behavioural attributes that you do. And there’s always the potential that they may in some ways be more sophisticated than we are. They certainly are in their use of acoustics.

How would you describe a sperm whale to someone who has never seen one?

They are extraordinary-looking creatures. If you’re on a boat and they are at the surface they can look a bit like a log – not all that impressive. But when you get in the water the whole picture changes. For a start, they are enormous. If you’re looking at a whale from the side, two things stand out. Firstly, the head, which is vast. It takes up a quarter to a third of the body, and bulges out with the great jaw slung underneath. Secondly, the large-scale wrinkles on the body behind the head look archaic and make it seem almost gothic.

But the most impressive view is from the front, where you see the enormous head coming towards you and the jaw beneath it outlined in white, and the eyes either side. It is like nothing else I can think of.

Why do they look so strange?

They have some unusual structural features. Principally, they have the huge spermaceti organ, which dominates that vast head. This organ produces the click sounds that the whale uses to echolocate and communicate.

It’s the world’s most powerful sonar system. Almost all sperm whale sounds are in the form of clicks, so it’s a large part of what they do and what they are. A Danish scientist, Peter Madsen, has worked out that in its lifetime a sperm whale makes about half a billion clicks. One of his colleagues, Magnus Wahlberg, has also pointed out that a sperm whale’s frown could lift a truck, such is the power of the spermaceti organ.

Also in that head is the largest brain of any animal on Earth.

What are sperm whales like individually?

The first impression is that they are timid and easily startled. I’ve seen a group of 15 or 20 of them lying at the surface when a fur seal, which has less than one per cent of the body mass of a sperm whale, popped up in front of them and made a splash. They all freaked out and dived.

You’ve claimed that sperm whales have culture. What’s the evidence?

We noticed that different groups of sperm whales consistently made different patterns of sounds. One group would be going, “click click click – click”, while another would be going “click click – click click”.

The only reasonable way to get this pattern is through social learning. To get it to happen genetically takes a huge stretch of the imagination. We have found that the click patterns are specific to particular “clans”, containing thousands of animals – much larger social structures than the whales’ basic matriarchal “family” units. Members of each clan share a dialect.

Then the question becomes: do they share any other cultural traits? We have found there are substantial differences between clans. For example, they move in characteristic ways, and have different feeding success when in the same area at the same time.

You’ve also claimed that these cultural differences affect genetic evolution, something previously found only in humans.

Sperm whales have very low diversity in their mitochondrial DNA (mtDNA), which is inherited only from the mother. And they have a matrilineal social system, which means that females remain with their mothers’ social unit throughout their lives.

So say a set of females possess a cultural trait, such as baby-sitting or a feeding pattern, that gives them a selective advantage so that they have more offspring on average. My idea is that if they pass this trait on culturally to their female descendants in the social units, at the same time as they pass on their mtDNA, then the mtDNA of the animals who originated the trait will spread. Eventually it will dominate the genetic structure of the population, leading to the low diversity.

Could there be more to whale culture?

Mass strandings are a real puzzle. I think they could at least partially be a result of cultural behaviour. Some of the strange things about human societies that don’t seem explicable through genetic evolution, such as kamikaze pilots, you can explain through cultural evolution. I wonder whether it might also play a part in seemingly inexplicable things in whale societies, like strandings.

How do their social structures compare with ours?

A sperm whale is born into the social milieu of its mother’s social unit. Most females will spend the rest of their lives within that unit. Males leave at about six years old, forming a temporary bachelor group, and becoming more solitary as they age and grow.

Some of our studies of social structures suggest there is an extreme form of harmony within the groups, of a kind that you don’t see among terrestrial mammals. On land, animals tend to compete for resources pretty vigorously. Normally even cooperative relationships among land animals have an element of competition, conflict and hierarchy.

We have looked for evidence of hierarchies and dominance within the social units of sperm whales, but have found none at all. There is no evidence even that they have preferred companions within the group. All the individuals in a unit seem equally happy in each other’s company, whether they are related to each other or not. They prefer members of their own unit to any other, but within that unit, social life is very homogeneous.

This may be because the structure of the ocean is so different to that of the land. Competition is on a very different scale, which perhaps allows for more cooperation and more social homogeneity.

Do you find yourself getting emotionally involved?

Yes, definitely. I don’t often actually see them being threatened. But when you do, that’s when you can tell you feel an empathy – when you see one caught in a fishing net, for example. You think of that individual and how its life is now constrained, and the pain it has.

It also feels like a violation – these animals live far out in the ocean, a long way from most human influence, which is pretty rare nowadays, and it’s dispiriting to see their habitat invaded like that.

How do you feel when you hear about the Japanese killing sperm whales for “scientific” purposes?

I am a scientist, and I value my profession and its integrity. “Scientific whaling” is like the prostitution of the profession: using the name of science for a totally bogus purpose.