New PBS documentary explores humanity’s footprint on nature

HUMAN FOOTPRINT, a groundbreaking six-part science documentary exploring the complex ways in which humans are currently transforming our planet, premiered yesterday on PBS, PBS.org, and the PBS App.

Produced by Day’s Edge Productions and hosted by Shane Campbell-Staton, an evolutionary biologist at Princeton University, this stunning series takes viewers on a fascinating journey around the world to dissect the myriad ways in which the Earth’s most invasive species is currently leaving its footprint all over the natural world, giving rise to an unprecedented cascade of physiological and behavioral changes in a variety of animal and plant species. 

Yet, instead of being a “doom and gloom” story of human villainy, the series aims to provide an honest reckoning with our species’ intricate connections to nature and singular history of fundamentally changing the Earth’s ecosystems, while also highlighting non-human life’s amazing resilience to anthropogenic stressors.

“We’re thrilled to share HUMAN FOOTPRINT and Dr. Shane Campbell-Staton with audiences around the world,” said Neil Losin, owner and senior producer at Day’s Edge. “Now is the time to ask the big questions about humanity’s past, present, and future, and Shane’s knowledge, curiosity, and humility make him the perfect guide for this unforgettable journey.”

Shane Campbell-Staton: A biologist mapping the Anthropocene 

Shane Campbell-Staton is an assistant professor of Evolutionary Biology at Princeton investigating human-driven evolution in our current geological epoch, frequently referred to as the “Anthropocene,” and defined as a period in which human activities have a significant and lasting impact on Earth’s geology, climate, and ecosystems. 

By integrating a diversity of experimental and methodological techniques, Shane and his team at the Campbell-Staton Group explore the effects of urbanization, invasive species, climate change, and other human-related changes on wildlife in order to better understand the future of biodiversity in a human-dominated world. 

Since human modifications to the natural world present extreme and novel environments for a variety of species around the world, they offer unique opportunities to study the process of evolution in real-time and shed new light on nature’s extraordinary capacity to rapidly adapt and evolve in response to human-induced stressors. 

Shane’s research highlights non-human life’s extraordinary ability to rapidly evolve traits for protecting it against ever increasing human encroachment. Some examples of this phenomenon include anole lizards living in sprawling South American metropolises increasing their heat tolerance to adapt to urban heat islands, and grey wolves from Chernobyl evolving an amazing capacity to withstand massive amounts of radiation in just a few generations. In Mozambique, a rising number of elephants are born tuskless to gain better protection against ivory trade, 

In HUMAN FOOTPRINT, Shane draws upon his groundbreaking research to map humanity’s massive impact on other species, while stressing the latter’s incredible resilience against human domination. “Hosting HUMAN FOOTPRINT has been one of the greatest adventures of my life. I study how animals adapt to the changes we are making to planet, but this journey really helped me to better understand the depth and breadth of our impact,” he said. “We are so intricately connected to the world around us in so many ways. I hope this series helps others to see and think about those connections in new ways.” 

Pilot: What makes a species invasive?

In the series’ first episode, which just aired on PBS on Wednesday July 5, 2023 at 9 p.m ET, Shane takes his viewers on a trek from South Florida and Illinois to the American West and Hawaii to explore a diversity of so-called “invasive species” – ranging from pythons in Florida and Asian carps in Illinois to wild horses in the West and virtually all animal and plant species currently inhabiting Hawaii. 

Biologists define invasive species as organisms (plants, animals, or microorganisms) that are non-native to a particular ecosystem and have the potential to cause harm to the environment, economy, or human health. These species are introduced either intentionally or accidentally to new habitats, where they can outcompete native species, disrupt ecosystems, and alter ecological processes.

Although this definition looks rather straightforward, Shane is careful to emphasize the inherent difficulties in classifying a particular species as invasive, and embarks upon an in-depth discussion of concepts such as “nativeness” and “belonging,” while highlighting the intricate relationship between biology and culture when trying to understand invasive species. 

Humans: The most invasive species of all

While acknowledging the unmistakable negative impacts species deemed as invasive have on their current ecosystems, he nevertheless argues that the situation is much more complex than usually thought. He notes  that humans often play a disproportionate role not only in classifying a species as invasive or not, but also in the relocation of such species to new habitats in which they could potentially cause significant harm.

“Humans are a cosmopolitan species, one of the few. And wherever we go, we bring other species with us, sometimes on purpose, sometimes without even knowing it. When the conditions are ripe, it’s a bonanza for these alien species. They multiply, spread, and wreak havoc in their new environment. These biological invasions cost the global economy 1.4 trillion dollars a year and, after habitat destruction, they’re the leading cause of species extinctions,” explained Shane.

“But are invasive species really the villains? After all, when an arsonist starts a fire, no one blames the match. So, instead of vilifying the species that succeed where they don’t belong, we should take a closer look at why they are there in the first place and how our species is handling the fallout.”

For instance, the large number of pythons currently roaming through a wide range of South Florida’s natural areas and causing significant harm to local ecosystems would not have ended up there without major increases in inter-continental wildlife trade over the past decades and the subsequent careless discarding of pythons initially bought as pets into the wilderness. 

Similarly, the several species of Asian carp originally imported in the 1980s and released in US rivers and lakes to help cleansing the massive amounts of human waste reaching these waters have since multiplied exponentially, endangering local aquatic species, and – in a culture still hesitant to consume them as food – incurring massive costs to devise various technologies to control their spread. 

Such examples highlight the huge impact human actions can have on the relocation of animal species, and the unforeseeable consequences such actions often entail. But while the negative impact of species like pythons or carp may be straightforward, other cases such as the horses introduced by the Spanish on the American continent at the end of the 15^th century raise an entirely different set of questions. 

Although these horses are clearly non-native to the Americas, in the centuries since they had been introduced, they have nevertheless become close to a national emblem, being widely used and praised by both Native Americans and the newly established immigrants arriving from other parts of the world. And if American people now try through a variety of methods to get rid of pythons and carp, their deeply rooted attitude towards wild horses is highly different, regardless of the fact that horse populations are doubling every few years and are currently ten times larger than the land can sustain. 

As Shane puts it, while our desire to keep wild horses in the West might be rooted in our culture, its outcome remains biological. “But is our love for a species enough to make it belong, and at some point, as an invader, deserve amnesty?” he wonders. 

Finally, by taking a close look at the exuberant flora and fauna of Hawaii and their centuries-long relation to local people, he further stresses the difficulties in classifying certain species – including humans – as being native to a specific place or not, and the disproportionate role of cultural attitudes in framing the answer to this question. “Our perspectives about nativeness are shaped by our own sense of belonging as much as anything biological, whether we are talking about our own species or another,” he argued.

These musings converge towards a rather grim outlook on our own species, which can easily be considered as the most invasive species of all. “Maybe the reason we have such strong feelings about invasive species is that we see part of ourselves in them. Because invasions start with us. They get out of control when we’re slow to take responsibility. And they highlight the uncomfortable truth that humans are quite capable of doing things we can’t undo,” Shane said.

Yet, a certain degree of optimism resurfaces at the end of this first episode. “Even if somehow we could get rid of the invasive species, we wouldn’t end up with the ecosystems we had at the start. We can’t turn back the clock. But what makes our species special is that we can see what lies ahead, and we can protect the things we care about. We just have to decide what we value, and, in the world we want to live in, what belongs,” he concluded.

What to expect next

In the following five episodes, airing each Wednesday at 9 p.m. ET until August 9, Shane will further expand not only upon how human activities impact the natural world and what this tells us about human nature, but also – and perhaps even more importantly – upon how nature itself can often fight back through complex strategies and successfully withstand human invasions. 

While humans have traditionally been praised as guardians of nature, increasing evidence now mounts that we could just as well be seen as nature’s top predator, using our biology, culture, technology, and economy to wreak havoc on non-human life forms for our own benefit. Yet, as the series proceeds, it will become clear that non-human animals and plants can be extremely resilient to human predation, and are able to use a dazzling variety of strategies to deal with our merciless raids on nature. 

Whether by forging affective bonds with humans as wolves did in their journey towards becoming domestic dogs, or by cunningly adapting to human-made habitats such as sprawling cities, as rats are doing in the back alleys of New York, the species with which we share this planet do not fail to prove to us, again and again, that our dreams of control and dominion are more fragile than we would like them to be. Instead of being separate from nature, we are just a small, vulnerable part of it. In a complex world hosting an enormous variety of highly intelligent and adaptable life-forms, rather than being indelible, our human footprint could easily vanish from the sands of time. 

As Shane brilliantly puts it at the beginning of the first episode, “this isn’t a story about starlings or any of the other invasive species spreading across the planet. It’s a story about one species that moves others around the globe like pieces on a chessboard. The problem is, depending on where they land, sometimes those pieces start playing their own game.”

Further information about the series and related topics can be found in Shane’s recent TED talk and NPR interview.

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By Andrei Ionescu, Earth.com Staff Writer

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