In this interview, AIQ catches up with biologist and science writer Sean B. Carroll about nature’s hidden connections and why human beings must act to reverse biodiversity loss.

Read this article to understand:

  • How humans are damaging biodiversity
  • The risks biodiversity loss pose to economies and societies
  • The commercial opportunities for companies that act on biodiversity

Serengeti National Park in Tanzania is famous for its teeming grasslands. In the 1960s, scientists wanted to quantify this natural abundance, so they flew back and forth in a plane, meticulously counting the animals on the savannah. They recorded precisely 99,481 wildebeest, 1,813 buffalo and 60 elephants, alongside many other species.

Continuing their surveys over the subsequent decade, the scientists found the numbers of most animals were rapidly increasing. The reason was simple. Shortly before the count began, the cattle farmed on the edges of the park had been vaccinated against rinderpest, a disease that also affects buffalo and wildebeest. With rinderpest no longer killing the wild animals, their numbers rebounded.

By 1977, there were an astonishing 1.4 million wildebeest in the Serengeti. Some experts believed the vast herd should be culled, fearing it would damage the wider ecosystem. In fact, the opposite happened. The park thrived. The wildebeest cropped the grass, which meant less fuel for wildfires; fewer fires meant more trees; more trees meant more food for giraffes and other animals. As a “keystone species” - and one of the first known non-predatory keystones – large numbers of wildebeest were crucial to the health of the Serengeti.

Science writer Sean B. Carroll, Professor of Biology at the University of Maryland – College Park, told this story in his 2016 book, The Serengeti Rules: The Quest to Discover How Life Works and Why It Matters. Later turned into an award-winning documentary, the book describes how scientists came to learn the ecological principles of balance and regulation that govern life on Earth, from the number of cells in the human body to the workings of vast biological systems.

Carroll argues it is vital we understand these principles to avoid further damaging the world’s biodiversity and intervene where possible to help restore it. After all, this is not just a matter of protecting nature but also looking after the interests of human beings, whose societies, economies and markets are heavily dependent on healthy ecosystems. “This is not about making the world pretty,” Carroll says. “It’s about making it functional.”

In this Q&A, Carroll talks about the role of keystone species, the risk to human society from biodiversity loss, and the steps companies can take to reduce their impact on nature.

What are The Serengeti Rules and what do they tell us about how nature works?

Over the last 50 or 60 years, scientists have worked out the rules that regulate the numbers and kinds of animals and plants in any given place. The coining of them as “Serengeti Rules” was my doing – the Serengeti is a magnificent and inspiring place where you can see all these rules on display. I could have called them the Kansas Rules, but I don't think I’d have sold as many books.

The rules explain the often-surprising connections between creatures

The rules explain the often-surprising connections between creatures. Their discovery was an epiphany for scientists. Firstly, there is the sheer pleasure of understanding nature better and its hidden beauty. But there are also very practical things you can do if you understand the rules. By articulating some basic ecological principles about how nature works, the Serengeti Rules give us guidelines of how to manage nature – or when to let it be.

One of the rules concerns “keystone species”. What are they?

A keystone species has an outsized impact on the rest of the community in which it lives. The stability and diversity of communities can really hinge on just one species. This was first discovered in tide pools on the Pacific coastline of the American Northwest, where the starfish is a keystone species: without that predator in the system, the diversity of these tide pools collapses, and they get overtaken by a single species (in this case, molluscs or mussels specifically). When that principle was discovered again and again in different places, it became clear it is a widespread phenomenon.

Keystone species illustrate some of the hidden connections in nature

Keystone species illustrate some of those hidden connections in nature. For example, who would have thought trees need wolves? Whether you’re in the Highlands of Scotland or an aspen grove in the American West, wolves are needed to control the number of herbivores that would otherwise browse down and essentially stunt the growth and the abundance of trees.

In other cases, forests need fish: in the northwest Pacific of the United States and Canada, salmon play a key role in bringing nutrients in from the ocean to fertilise the forest. By understanding these connections, we now understand more – not only about how nature works, but why things could be unravelling and how the loss of a single species could have a domino effect on so many other things.

How do these domino effects work and how much damage do they cause?

What connects a lot of creatures in a system is the food web, or food chain. The way some keystone species influence the abundance of things is mediated through food. Predators, by controlling the abundance of herbivorous browsers and grazers, can influence the plant community. When you lose predators, you’re “downgrading” the system through an overabundance of browsers. This is clear in places like the United States with deer populations that are enormous compared to what they used to be. This overabundance of browsers and grazers can decimate the plant community and kill off diversity.

You have said “there is a risk we get used to a downgraded landscape as the norm”, citing the example of parts of the Scottish Highlands that are denuded of trees. How can we learn to recognise a downgraded landscape?

We see things we think are beautiful: they’re orderly, they’re green, that’s our sense of aesthetics. But we may not realise they do not, for example, contain nearly as much diversity and dynamism as they would if they had been left to their own devices.

We change nature according to our own aesthetic or functional desires

You may well be looking at a landscape very different from what it would have been 1,000 or 500 or 300 years ago, when native fauna and flora were around, doing their thing. Given a chance, we change nature according to our own aesthetic or functional desires.

But the good thing is that nature is remarkably resilient. Even when nature has been changed a great deal by us, these systems can re-establish themselves and diversity, those dynamic connections, can return, “upgrading” the system.

Do you have any examples of places where ecosystems have successfully been upgraded?

I’m happy to report this going on all over the world. And it’s going on at all sorts of scales: it could be as small as a local pond, where you’re getting rid of algae that chokes the water and fish and birds are returning.

On a larger scale, Yellowstone National Park reintroduced wolves after a 70-year absence. Just pause on that for a second. What can we possibly expect when returning a predator to a system where it’s been missing for 70 years? Well, when the wolves were reintroduced, biologists could detect significant changes in a really short period of time. And these changes were not only in things like elk populations, which fell due to wolf predation, but on tree populations. And when trees are more abundant, more plants start to grow along riverbanks.

A bunch of domino effects were unleashed when wolves were reintroduced into Yellowstone

You change the temperature in the shallow pools of rivers, which benefits the fish populations. And then, because you have food and building materials growing along riverbanks, beavers come back and start to build their dams, and that creates habitats for yet more creatures. So, a bunch of domino effects were unleashed when wolves were reintroduced into Yellowstone.

One of my other favourite examples, which I've been able to witness first-hand, is Gorongosa National Park in Mozambique. In Yellowstone, one species was missing; Gorongosa, because of the Mozambican Civil War and then civil disorder and poaching, had lost 97-98 per cent of all its large mammals since the 1960s. It was really given up for dead. But a public-private partnership was formed to manage the park, focusing not so much on reintroducing things but on protecting what was there and letting those populations naturally rebound.

The results are spectacular: what were probably just a few thousand large mammals left 20 years ago now total over 100,000. Elephants and hippos and lions are all doing well. More recently, they have reintroduced African wild dogs. That brings a double benefit: you are restoring a missing component to that landscape, but also helping protect an endangered species and give it a future on the planet.

This is happening all over the world. Lakes, rivers, landscapes, farms. There are many opportunities to give nature a chance to come back. What’s exciting is that things can change dramatically in five, ten or 15 years. The reward of doing this work is that nature comes back almost in real time, right before our eyes.

Countries like Mozambique face big social and economic development challenges. How important is it to ensure we take these priorities into account when seeking to protect nature?

In the 20th century, conservation was largely based on roping off nature and keeping people out. That’s just not going to work. These wildernesses are our reserves, they need to provide benefits to the people who live by them or else their existence is precarious.

Wildernesses need to benefit the people who live by them or their existence is precarious

There are still lingering tensions around the Civil War in Mozambique; there have been natural disasters recently, including three cyclones. Now the pandemic hits. This is a country with one of the lowest per-capita income rates in the world. That’s why it is important the Gorongosa project is as much a human development story as a conservation one. The project has brought benefits through economic development, healthcare and education.

What is the risk to societies and economies more broadly if we don't act to preserve biodiversity?

I know when I talk about wildernesses and wild dogs and wolves, these are not necessarily bread-and-butter issues for the average person. But these are areas where we’ve discovered principles that help us understand how to manage things a little more proximate to our lives: our freshwater sources; ocean management. We’ve commandeered about half of all the habitable land on the planet for agriculture and that has significant consequences. It is a huge contributor to climate change. And habitat loss is the major driver of biodiversity loss.

Human life requires food, water and air, and the services provided by natural systems are really significant

This is not about making the world pretty: it’s about making it functional. Human life requires food, water and air, and the services provided by natural systems are really significant. As we degrade those systems, we degrade their ability to give us what we need on a planet that has to sustain billions of people.

We’re dependent upon pollinators for food security, for example. And, as everyone knows, pollinators – species like honeybees and birds – have seen their populations seriously impacted. Somewhere around a billion people a day depend upon protein from the ocean. Monitoring fish and shellfish stocks is really important given lots and lots of places are now overfished. After a little bit of reprieve, the ocean is so vastly productive that a lot of stocks can come back. But they need to be actively monitored and managed.

Let’s take another example: watersheds. We many want the timber on a hillside. But removing the trees may erode materials off the hillside. Those forested slopes act as sponges, slowly releasing water into rivers; when you take that capacity away, you are now drying out the surrounding land and removing a predictable water source for entire downstream communities. We have to understand these connections, how these resources work, and how our actions influence the ability of the planet to keep providing them.

An overarching theme of The Serengeti Rules is the role of regulation: you argue “everything is regulated”. Can we extend the analogy to human activity? Do we need greater regulation of human and corporate behaviour?

Well, we certainly need regulation to be applied. Whether we need new regulations, or just enforcement of existing regulations, it probably depends jurisdiction by jurisdiction.

We certainly need regulation to be applied

We might not give much thought to a seaside development that damages a reef. Nobody may notice the filling-in of a marsh. But marshes and seagrass are carbon sinks: they’re also habitats; the reef may be a breeding ground for fish that are of commercial significance. Mangrove forests buffer us from storm damage and store carbon. To undertake these developments without considering the potential consequences is becoming expensive.

What can individuals and organisations do to protect biodiversity?

One option is to look for partnerships with organisations involved in protecting nature. We are starting to see more of that in the US, where companies can seek environmental sustainability certifications. The Audubon Society, for example, certifies various activities as environmentally sustainable. Reaching out to large environmental organisations such as the World Wildlife Fund for Nature for expert help and guidance can help companies promote development without causing unintended and drastic side effects.

The new era is about collaboration, not conflict

The new era is about collaboration, not conflict. There’s a history of the environmental movement being antagonistic towards corporate culture or imperatives, and vice versa. But sensible people can sit down and say: “Wait, let’s think about the trade-offs that are involved in any actions we take, or the cost of inaction on a particular front, and how can we do things better.”

On the consumer-facing side, companies that do the right thing are also going to be welcomed by a consumer who is becoming more and more aware these are things to be concerned about, especially food and materials use. People are becoming more aware the choices they make at the grocery store with things like packaging matter cumulatively in the long run.

What is the relationship between climate change and biodiversity loss and why has it taken us longer to wake up to the threats posed by the latter?

Climate change and biodiversity loss are independent crises; if you could stop climate change right now, you would still have a biodiversity crisis. But now you have these two crises intersecting and we can't wait any longer to get serious in addressing them.

Climate change and biodiversity loss are independent crises

On climate change, people have experienced wildfires and droughts; they know these are of such a scale they are causing an economic impact, civil disorder, and migrant crises that are erupting everywhere.

Biodiversity loss is a little harder to figure out. Where is it? Why does it matter? In the developed world, we don’t really have a lot of concern about, say, food security – but problems with food security and clean water supply are showing up in other parts of the world. And long-term water supplies are under tremendous strain, even here in the US in places like Las Vegas, Phoenix and Los Angeles.

There’s also the problem of measurement. Is it more difficult to trace the range of impacts on nature than it is to record a single metric, as we have for climate change with carbon emissions?

Suppose you're a food importer in the UK and you want Brazilian beef. Well, Brazilian beef comes at a big cost, because the deforestation of the Amazon for the raising of cattle has been occurring in an unrestrained way, due to lack of regulation under the current Brazilian administration. And that leads to a combination of effects.

When you deforest, you liberate a lot of carbon and degrade that soil

When you deforest, you liberate a lot of carbon. Second, you degrade that soil. Third, raising cattle is – and this is a scientific point, not an ideological one; I'm a meat eater – a very inefficient source of calories for humans, and the most taxing sort of calories we make anywhere on systems in terms of water energy and the carbon footprint.

Then you have to take into account that the Amazon is essentially a weather-making system. The loss of that forest is leading to desertification, for example in northeastern Brazil. This will make all those lands much less useful, but the dire consequences will also be felt on a global scale. When we create demand for things in certain parts of the world, these are the domino effects that can unfold. If the damage goes too far, I don’t know that we can always repair it, especially if the soils are degraded in the Amazon to a point where they can no longer support tropical forest.

It has been argued COVID-19 indicates our broken relationship with nature. Do you agree?

Does it show a broken relationship or simply our intimate relationship with animals? However COVID-19 got into humans, it was probably through proximity to wildlife, maybe through a domestic animal or a market intermediate. The cycle of flu is catalysed by our living in close proximity with poultry, swine and other animals.

If you add together our species with all our livestock and domestic pets, we account for 96 per cent of the mammalian biomass on the planet. All the other mammal species together are just four per cent. Our relationship with animals, if not broken, is at least dramatically different than it was 10,000 years ago when there were a million or so humans on the planet. It’s a dramatic inversion of the order of things.

The pandemic shows us lots of things, how the globe is connected; how something that happens over here can affect everybody. That’s a good lesson for understanding how some of the domino effects can resonate throughout the planet’s support systems. And we do have to think hard about our relationship with animal life, especially the huge proportion of it we devote to agriculture as this has an enormous footprint on the planet and increases the risks of zoonotic outbreaks.

You’ve written about the importance of retaining optimism. How can we stay hopeful and avoid pessimism as we work to protect biodiversity?

I don't think there's an alternative. It has been said pessimism is a self-fulfilling prophecy. If you don’t see hope, you won’t find hope, and you won’t pursue hopeful things. I think you have to be an optimist. If you see glimmers of things that work, you can try to scale them up and share them across the world.

Some of the most degraded places and threatened species have come roaring back when given a chance

When I wrote The Serengeti Rules, I talked to ecologists in various places. I was asking myself the question: “Are we doomed or is there time to change the road we’re on?” I was delighted to find plenty of evidence there’s time to change the road we’re on and some of the most degraded places and threatened species have come roaring back when they have been given a chance.

A lot of this is about giving life a chance and a little bit of time – and not as much time as some people might think. Here’s the great bullet-point for the financial world – not nearly as much money as you might think, either. It is amazing how cheap a lot of this work is. That represents a huge opportunity for philanthropic organisations and governments because nature does a lot of the heavy lifting in restoration work; the bang-for-your-buck is terrific.

What is holding us back is not money: it’s a little bit of knowledge, a little bit of will, and a little bit of figuring out how you balance the sometimes-conflicting interests that may be out there; the development interests, say, against the long-term sustainability interests. But I don't think these are impossible puzzles to solve.

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