David Barrie Explores The Science Behind How Animals Find Their Way In 'Supernavigators'
ARI SHAPIRO, HOST:
Author David Barrie is fascinated with animal navigation.
DAVID BARRIE: When a wasp flies off on a hunting expedition, how does it find its nest again? How does a dung beetle roll its ball of dung in a straight line? After circling an entire ocean, what strange sense guides a sea turtle back to the beach where she was born to lay her eggs?
SHAPIRO: Turns out sea turtles use the alignment of the sea's waves to leave the shore and the Earth's magnetic field to guide them back. That's just one of the many hows that Barrie answers in his new book "Supernavigators." I started off asking him why animals would need to navigate with such precision.
BARRIE: Well, often when we're talking about migratory animals, it's about returning to a place where they can breed successfully, and breeding successfully means having access to the right supplies of food. It means a place of relative safety from predators and disease and so forth. So many, many different kinds of animals have developed these extraordinary migratory strategies that enable them to breed successfully and therefore to maintain their species.
SHAPIRO: And there is no one answer to this question of how they do it. As we go through the book, we meet some animals that use sense of smell, others that navigate based on polarized light, others on magnetism. It seems that there are as many ways to find your way as there are species you write about.
BARRIE: Yes and probably quite a few we don't know about yet, too. But I think one of the other things I learned in researching this book is that no animal that's been really well studied relies just on one mechanism. There's always a degree of redundancy. You know, they have several - maybe four, five or six - different mechanisms that they can use, and they can switch from one to another depending on need. So in many ways, it's just like human navigators.
SHAPIRO: I went into this book kind of assuming that animals with bigger brains would have more advanced navigational capabilities, and that's actually not true at all. You give some really impressive examples of tiny animals with tiny brains that can do remarkable things. Will you tell us about one of them?
BARRIE: Well, one of the ones that fascinates me is an animal called the desert ant which lives in the Sahara Desert in North Africa. And the desert ant is astonishing. You know, it's this tiny animal with a little brain, you know, the size of a pinhead, and it can use the sun. It can use polarized light. It can use wind. It can count its steps to work out how far it's gone like an odometer. It can use landmarks, and it - now, very recently, it's turned out that it also has a magnetic compass sense.
SHAPIRO: How does an animal with a brain the size of a pinhead have all those things going on?
BARRIE: Well, that is a fascinating question, and we don't fully know the answer. But insect brains have evolved over hundreds of millions of years. I mean, don't forget human beings - we've only been around in our present form for about 300,000 years. So insects have had hundreds of millions of years to perfect the most economical, efficient navigational systems, and they are breathtaking, absolutely breathtaking.
The desert ant is only one example. The Bogong moth in Australia is another extraordinary migratory animal. It goes a thousand or more kilometers, and it uses the Earth's magnetic field to set its course. But it also - and again, this is very hot news. It also, believe it or not, uses the alignment of the Milky Way in the night sky.
SHAPIRO: (Laughter) I love that definition of hot news.
SHAPIRO: This just in - the Bogong moth uses the alignment of the Milky Way in the night sky to find its way. You heard it here first.
BARRIE: Well, some people think that's exciting.
SHAPIRO: There's a great story in this book about how humans first got hard evidence that birds make long migrations from one continent to another. Tell us about the arrow stork.
BARRIE: Oh, (laughter) the arrow stork - it's a sad story, really. But in the 1820s, there'd been a lot of argument about what happened to birds that disappeared in the winter. Did they...
SHAPIRO: Go to the moon?
BARRIE: Did they go to the moon - yes, seriously. Some people thought that maybe they went to the moon, or maybe they disappeared under water and slept at the bottom of ponds. But in the 1820s, somebody spotted a stork in a town in North Germany with an arrow stuck right through it. And when they caught the stork - I have to say; I think they probably killed it first, which is a bit sad - they discovered that the arrow was an African arrow. So this stork had been shot by an African archer, so it had to have been to Africa. And it became known as an arrow stork.
SHAPIRO: Do humans have these innate abilities to navigate the way that other animals do?
BARRIE: Well, I believe we do, but we have to cultivate them. The trouble is that we've been civilized now for a little while, and we've become more and more dependent on technology. You know, 800 or 900 years ago, the magnetic compass came into use, and then we had, you know, the sextant and the chronometer and so on. Now we've got GPS.
GPS is a marvel. I mean, it is an astonishing technological achieve, but our increasing and exclusive reliance on it is turning us into kind of navigational idiots. We're losing the ability to exercise our natural skills. And from my perspective, almost more sadly, we're being more and more cut off from the natural world as a result. We no longer look up from our little glowing screens and observe the world around us. And I think we may discover that this has quite profound implications both for our physical health but also for our spiritual health, too.
SHAPIRO: There are some groups of humans that are trying to revive these ancient navigation techniques. For example, you mention the Polynesian Voyaging Society.
BARRIE: Yes. This is a really rather wonderful revival that's taken place over the last 40 or 50 years or so. In the 1960s, the traditional skills of the Pacific island navigators, which are truly breathtaking, had almost disappeared. But just by the skin of their teeth they were preserved, and a few of the old expert navigators were persuaded to come and teach a new generation of navigators. And the Polynesian Voyaging Society was established in Hawaii, and then various other voyaging societies have been set up in other parts of the Pacific.
So in fact the traditional methods of Pacific Island navigation using the sun, the stars, wave patterns, clouds, the behavior of animals and so forth have been saved. But there is a danger that the skills employed by the Inuit up in the Canadian Arctic, for example, or the aboriginal tribespeople of the desert in Australia - some of those may not survive unless steps are taken to preserve them, and I worry about that.
SHAPIRO: Why does it matter that human abilities to navigate survive?
BARRIE: Because they are amongst the most beautiful cultural artifacts. I mean, our ability to navigate using our senses and our native wits was a key to our survival for the first 290,000 years of our existence as a separate species. And for those extraordinary abilities to be lost just because it's more convenient to push a button and read out a number on a screen would be, I think, a tragedy.
SHAPIRO: David Barrie - his new book is "Supernavigators: Exploring The Wonders Of How Animals Find Their Way." Thank you for speaking with us.
BARRIE: Thanks very much.
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Correction June 6, 2019
A previous headline and Web introduction to this story incorrectly spelled author David Barrie's last name as Barre.