TF: There are two schools of thought as far as these extinction-related scenarios go. One is that a specific cause has been the major cause of extinctions. The other argues that there are a whole combination of factors that have been important. A good example would be the idea that somehow human hunters and climate have worked together to cause extinctions.

An analysis of that would be: All right, let's accept that on face value, and then look at worldwide extinction patterns. What you find is that extinctions happened before the ice age in Australia, just after it in North America, and only 600 to 800 years ago in New Zealand. If you take that argument -- that both climate and people are working together -- what you have to accept is that climate is a very weak factor. Because extinction happens no matter what the climate is doing; it's when people arrive that determines when extinction happens. I think that the analysis, as far as I've seen, probably still overwhelmingly supports the single cause, which is, I think, just overhunting.

Q: What are the most significant threats to biodiversity?

TF: The single most significant threat to biodiversity is human population size and growing demand. We're running out of fresh water; we're tapping ever more river systems to provide ourselves with water. In the city I come from, Sydney, for every person that lives there, we need a storage capacity equal to three Olympic swimming pools worth of water. As you add population, you're adding immeasurably to the water demand. We're now tapping catchments many hundreds of kilometers away from the city. So you can see how the impacts tend to grow, just as population grows. There is also the problem of what we call "affluence." Maybe people are using water unwisely, or just using too much -- and this is all very true, as well. But unless you can cap population, you'll just have that demand going on forever.

Q: Why does this matter to the ordinary person?

TF: I'd say to them that if they want to have clean water, clean beaches, clean air, and a somewhat enjoyable, diverse environment, then they'd better start taking note of this biodiversity crisis. At the moment, we're basically cashing in on the planet. The ecosystem's ability to provide clean water and clean air, and just the greenery around us -- we're cashing all of that in just for dollars, and that's very silly. One day people will turn around and things will be dirty and polluted, and there'll be no jobs for their kids.

Q: What are the steps to take to conserve biodiversity?

TF: The first thing I think we need is a world population policy. Each nation has to have a population policy -- that is strategic. It's not that you're going to stop growth tomorrow, but that, in the long term, you'll get onto a trajectory which will lower growth rates. Secondly, we need to do accounting differently. We need to actually add up environmental capital and social capital -- because they're two very important forms of capital -- and balance them against financial capital. All too often, what we call "profit" is just capital transfers from environmental or social capital into actual money.

Q: Do you see any signs of hope, of positive steps?

TF: I do, actually. I think the fact that the world is more aware than ever of these trends is very, very important. The fact that this conference is happening here in New York, and has been sponsored by the Biodiversity Center -- which is a new thing at the Museum -- is all very positive. Just regionally, where I come from, we had our first state-of-the-environment report -- a big, 600-page document -- which was an attempt to do some environmental accounting. And we actually put dollar values on things like degradation of fisheries and waterways. You end up with a very persuasive argument if you do that. You can say to the people: Here are the billions of dollars which are being wasted here, which we're actually losing . . . or the equivalent thereof in environmental services.

Q: In what other ways is the current extinction event different from those of the past?

TF: I think we have moved down through the trophic levels; and what we're doing now is attacking soil and water. I mean, we've had our big hit at the megafauna; we've exploited plants and forests. But in a lot of the world now, what's under threat are soil, and water-based ecosystems. And once you start attacking the ecosystem at those very fundamental levels, you're doing something quite different. The last time biological productivity was attacked at such a fundamental level was probably during the Cretaceous extinction, when photosynthesis was interrupted, through, we think, an asteroid.

Q: What is the most striking evidence to convince skeptics that extinction rates are high?

TF: Well, again, from my corner of the world, we have lost 10% of our mammal fauna, pretty much in my lifetime. A lot of species seemed to survive to the 1960s -- they're now gone. Our frogs are having a dramatic decline. The common frogs of my childhood, which I played with and grew up from tadpoles, are now on the endangered-species list. Some of them are actually extinct. So these are things that are happening all around where I live, and I guess similar things are happening here. These are very real changes that, in my short lifetime, I've noticed. And, you know, when you think that you're dealing here with a world system that's been this way for millions of years, and within my lifetime we're starting to dismantle it -- I mean, that has to be cause for serious alarm.

Q: What are the things museums could do?

TF: Museums, in the 19th century, were the lens through which people saw the natural world. They didn't have the forms of transport or multimedia that we do today. So you'd go to a museum to understand the world. Now, modern museums have let a whole lot of other competitive resources erode that from them. There's David Attenborough on television, or there's a national park you can get to in a half a day's drive, or whatever. That's not necessarily bad. But what the museum needs to do is redefine its position. After all, we are the repository for many, many representatives of species that are now extinct. We're chockablock full of beautiful objects, real objects. It's like the equivalent of an art gallery, if you want. We can actually show people what they've lost, in a sense. I think part of the role of museums is to be beautiful, attractive, informative places that do show windows on the world. It's not the world that you see in a video -- it's the world perhaps as the place used to be. Perhaps it's looking at cultures, people, places, in the longer term, in the historic perspective. And that's something that only museums can do. Other media can't do that effectively, because they don't own the raw material.

Q: How can we go in and work with local people?

TF: I've attempted conservation programs in the southwest Pacific, and you realize that there is a fundamental gap in the way some people view the world, that is very different from your own. I may see an endangered tree kangaroo, or an endangered bat, or an endangered possum, and I think that I can see the reason for it -- overhunting or habitat clearance, but usually hunting. But when you speak to the local people, they have a totally different idea. What affects that animal's abundance, in a very real way for them, is the magic and ritual which is done around that animal. Whatever happens in hunting or gardening is just irrelevant -- it's what the clever men are doing. Or, you know, there's more over the hill. Well, you know, there isn't, but they just assume there is.

So it's very difficult, when you come across people with such fundamentally different world views as that, to actually win the argument. I mean, you can't. Their view is -- in many ways, at least to them -- and their experience is as valid as mine.

I think my great hope is to try to train local people, particularly those with some education, in Western ways of thought and communication. Then have them go back to their villages and try to do something at that level -- because they're in a far better position than I would ever be. I must say, of all of the programs I've tried in Melanesia, in terms of these conservation programs, only one was in any way successful, and that was probably fortuitous circumstance, rather than good planning. It's a very, very difficult thing to do.

Q: What patterns do you see in ancient extinctions?

TF: The important aspects of these Pleistocene extinctions are that they are in global in scale. Virtually every area suffers from them. And they correlate in time approximately with the first invasion of a naïve land by humans. As soon as humans arrive in a place, extinctions follow fairly quickly afterwards. In the case of Australia, for example, we know that people were in Australia before 35,000 to 40,000 years ago. Some people think it might have been 120,000 years ago. And we know that we get megafaunal extinction -- you know, everything in Australia that's bigger than a person goes extinct sometime before 35,000 years ago. Because of the nature of the dating techniques that are used at present, we can't be any more precise than that. But, certainly, it happened a long time ago. In the Americas, people came about 11,000 to 12,000 years ago, and that's when this great rush of extinctions happens here. In New Zealand, people arrive 800 years ago, and extinctions follow hot on their heels there, as well. Although we can't be precise about how rapidly these extinctions happened after people came in, I think I'm fairly safe to say that within a millennium or two, anyway, the majority of the extinctions were finished. So these are rapid, very dramatic events, that followed quickly on the heels of the arrival of people -- and they're not related to any patterns in changing world climate.

Q: In what way did humans coming into new lands precipitate extinctions?

TF: To understand this, we have to look at those few parts of the planet that escaped human influence until recently. One of the best examples of that is Lord Howe Island, which was the only island in the Pacific of any size that was totally uninhabited and unknown until Europeans discovered it in 1788, and also the sub-Antarctic islands in Antarctica. There you see basically a naïve fauna. The birds of Lord Howe Islands can be plucked off branches in the tree like fruit. You could go up and lift a pigeon off its roost and take it to your abode. If that was too hard for you, you simply broke the legs of any one of the ground birds, and it would cry out, attracting all of its neighbors. So you would get a dozen or two dozen birds in an hour or so. These things are documented -- they actually happened on Lord Howe Island. In the sub-Antarctic islands, you see a similar pattern. Even as formidable animals as elephant seals allowed themselves to be herded to the tri-pots, where they were knocked on the head with a stick and boiled down. These animals were naïve -- they had no idea that humans were a problem.

You can imagine then the first humans coming into North America, or Australia or New Zealand -- there's been nothing like a hominid in any of these places before. And, in Australia's case, nothing as big that's a warm-blooded predator. Of course, the prey species don't recognize humans as a problem, and they don't get a chance to learn -- particularly the larger ones, which are slow-reproducing and don't live in big herds. Humans can easily eliminate them. They don't run away. You put a spear through the ribs of the thing and it's dead -- it doesn't get a chance to learn. And, very rapidly, you run through any of the vulnerable species. And under those conditions humans have left all of their disease behind, too.

Q: What do ancient extinctions tell us about predicting extinction patterns now and in the near future?

TF:The past is the key to understanding the world we're living in today, because all of those extinctions have happened so recently, in geological terms, that there has been no evolution of new species to take over these vacant niches. We're living, essentially, in a crippled world. In Australia, nothing bigger than a kangaroo survived. There are empty niches out there for 55 species of large mammals, reptiles and birds. That concept is important in understanding how these systems work today and how fragile they are.

Another example from Australia is the introduction of rabbits and foxes. In 1850, Europeans brought rabbits to Australia, released them -- and, of course, they became problematical. There's an empty landscape here, vast amount of resources for these rabbits to use. If someone had introduced rabbits into the Serengeti Plain, you can be certain that that rabbit would be outcompeted, tromped on, or eaten by one of the megaherbivores there. Take all the megaherbivores off the Serengeti and put the rabbit in, and all of a sudden you've got a problem species -- a pest species. So these ancient extinctions have patterned the world that we live in today. We can't understand the interactions of what's happening without cognizance of those structured ancient ecosystems, which are now badly crippled.

The second point is that this is an ongoing process, particularly in the Third World. In Melanesia, where I work, you can see that in the past everything bigger than 20 kilograms in size became extinct -- I think through just overhunting. That process continues today. Everything above 5 kilograms in weight in New Guinea today is under threat from overexploitation. And you're dealing here with a land whose population has trebled or so in the last 50 years, where technology has shifted from bows and arrows to shotguns, where there's now roads and airstrips and the potential for trade right around the island. All of this is just increasing hunting pressure, you can see that people are just drawing down on the resource base further.

Here, in the developed world we've gone beyond that, and we now are taking the soil and water of these ecosystems. When you start dealing that low in the tropic system, you're actually precipitating extinction events on the scale of the Cretaceous extinctions -- where photosynthesis is interrupted and you get a big cascade. Here we're taking soil and water, and that kind of interruption in the end will have very profound effects.

Q: Could you explain the concept of "aftershock"?

TF: I've coined the term "aftershock" to deal with all of the consequences of megafaunal extinction, which I think are very profound. You have ecosystems which have many, many holes in them -- if you want, they're inhabited by ghosts -- because these extinctions, in geological terms, are so recent that nothing has evolved to fill those niches; they're still empty. It also has a profound effect on nutrient recycling. When there was megafauna about, grass would grow. It would be cropped off; it would be dropped out the other end of whatever happened to have eaten it; and 48 or 72 hours later, with the help of dung beetles, the nitrates and phosphates are back in the soil. Basically, it's like an economy where the money's going around very rapidly.

Once you take out megafauna, the only substitute is fire -- and, of course, fire is a much rarer event. In Australia we typically have to wait 10 to 20, maybe even 30 years before those nutrients are released. And, when they are released -- many of them are destroyed in the process. Nitrates, for example, are just volatilized and lost to the air; soil sulfurs are destroyed by the heat of the fire, as well. It's a much less efficient system. You end up having very profound effects within nutrient recycling of plant communities, and everything else.

There are many, many effects of this aftershock. The world we inherit, that we live in today, is the result of megafaunal extinction aftershock. It's not a balanced, co-evolved system -- it's one which is in severe disequilibrium. And it's continuing to rebound. So when we think of management -- of national parks and whatever else -- we have to take this into account. We're not dealing with the wilderness -- this is a very severely damaged ecosystem that we're trying to manage.

Q: What kind of discovery would change your mind about people being the major cause of extinction?

TF: One discovery that would make me admit that I've been wrong all along would be simply a long overlap between people and megafauna. So here, in North America, if you started picking up full megafaunal assemblages that were only 8,000, or 7,000 years old, or if you were picking up humans that were indisputably 15,000 years old, I would admit that I was wrong. But you'd want good evidence -- you'd want lots and lots of stacked dates in sequential sites, not just the odd date that looks a bit strange And a significant overlap between people and megafauna would have to be in the thousands of years -- perhaps between 5,000 and 10,000 years.

Q: Do you think the search for a cause of Pleistocene extinctions has ended?

TF: I basically do think that the search for a cause has ended in the majority of cases. There are many special cases that we still can't explain -- the extinction of insects in New Zealand, for example. But, basically, I'm satisfied, intellectually, that we understand the mechanism. The Blitzkrieg theory that Paul Martin has developed is universal; it's almost all-inclusive; it fits the known facts well; and, with a few small exceptions -- a few aberrant or unusual cases -- we have a solution to the nature, the causes of these extinctions. What really interests me now is the flow-on from those extinctions -- what the effects were. We've understood the cause, but the effects are another matter.

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