There's no getting back to nature: humanity has been changing Earth's landscape for millennia

Neanderthal man thinks about what he's done. (Okay, he was probably extinct already.) Image: AFP/Getty.

What is natural? It is often assumed that natural is better than artificial. Getting back to nature is something we should aspire to, with kids in particular not spending enough time in nature.

But if you want to escape civilisation and head into the unaltered wilderness you may be in for a shock: it doesn’t exist.

New research now suggests that there are practically no areas that have escaped human impacts. But not only that, such impacts happened many thousands of years earlier than is usually appreciated. In fact, you’d have to travel back more than 10,000 years to find the last point when most of the Earth’s landscapes were unaffected by humans.


The study, published in the Proceedings of the National Academies of Sciences and led by Nicole Boivin of the University of Oxford, catalogued changes in the abundance and diversity of plants and animals at the same time as human societies and technologies spread across the globe.

There is good fossil evidence for modern humans – Homo sapiens – being present in East Africa as far back as 195,000 years ago. Some 180,000 years later, humans were found on every continent except Antarctica. Over this period there were a series of collapses in biodiversity, with particular instances of extinctions of megafauna, non-domesticated land animals weighing more than 44kg.

Between 50,000 to 10,000 years ago, at least 101 of the 150 groups of megafauna species became extinct. There is much debate as to whether the disappearance of megafauna such as mammoths or mastodons was a direct result of human hunting, or a response to other factors. Correlation does not necessarily lead to causation: so evidence that large number of species disappeared from some regions around the same time as humans appearing could be due to a common factor such as changes in climate as the glaciers of the last ice age retreated.

Boivin’s study doesn’t produce a smoking gun that proves humans were responsible for such extinctions. Rather it uses traditional and new archaeological techniques to produce flint axes, plant pollen and burnt forest remains as evidence of the impacts humans had.

Extinction grabs our attention, but the data the international team has assembled tells a story of rapid change in not just the total number of species around the time that humans appear, but also the numbers of individual plants and animals in these ecosystems. Hunting and land clearing are the two main culprits in the oldest period they study – the Late Paleolithic (ending 10,000 years ago).

The study maps the spread of crops like wheat (A, in red) and livestock (Cattle, in blue) against the spread of human civilisation. ImagE: Boivin et al/PNAS.

After that, impacts shift up a gear with the development and rapid spread of agriculture. By this time roving bands of hunter gatherers begin to settle and plant crops and herd cattle. Today, we are used to looking out of an aircraft window to see broad expanses of intensively farmed monoculture crops. This trend began with the very first farmers who replaced diverse habitats with a small number of cultivated plants that in time would spread across the Earth, replacing whatever ecosystems they encountered.

The development of agriculture also included the domestication of animals, a few of which have expanded their ranges along with humans. Domestication of chickens happened some 10,000 years ago in East Asia. Earth is now home to over 20bn chickens, making it the most abundant bird species by some margin. The vast majority of the mass of land animals is now made up of humans and their domesticated species of cattle, pigs, sheep, goats and chickens.

When you include the accidental introduction of animals such as rats and invasive plant species, human agriculture meant profound alteration or sometimes complete replacement of indigenous ecosystems. The starkest examples of such changes are to be found on islands which often have high numbers of species that are not found anywhere else. Some examples are documented in more recent human history – the 17th-century extinction of the flightless dodo from the island of Mauritius being the most famous.


As well as detailing some of the havoc that humans have wrought on the biosphere, the researchers also highlight some positive interactions humans had. For example, the long presence of prehistoric societies that flourished within the Amazon basin show that careful stewardship of ecological resources – in that instance the cultivation of rich productive soils – can enhance ecosystems and provide sustainable livelihoods.

This is perhaps the most important lesson gained from the study. If we are to feed and care for the 9bn people that will be living on Earth by the middle of this century, then we need a more subtle and complex understanding of nature and sustainability.

The industrial age we now live in has taken human impacts to a planetary scale. We are changing the global climate and some argue that we have become a geological force. We can neither get back to nature nor continue as we are.

The state of nature – the situation of humans before the formation of societies – is a well used thought experiment in philosophy. It asks us to consider how societies and governments arise. What makes a good society? What is the moral basis of taxation?

An ecological state of nature – the biosphere as it was before human interference – is sometimes used in a very limited way when managing contemporary ecosystems. The assumption can be that we should simply strive to revert them back to their natural state. But can we say what that state is?

Alternatively, it could be used to pose both philosophical and practical questions. What sort of Earth system do humans want to live on? What is the role of other species in human well-being? What is the moral status of non-human animals?

Research that probes our ancient interactions with the rest of life on Earth can help us address such questions and so understand our current predicament. It remains to be seen whether Homo sapiens – which let’s remember is Latin for wise person – have the intelligence to learn from past mistakes and forge a sustainable future on Earth.The Conversation

James Dyke is lecturer in sustainability science at the University of Southampton.

This article was originally published on The Conversation. Read the original article.

 
 
 
 

CityMetric is now City Monitor! Come see us at our new home

City Monitor is now live in beta at citymonitor.ai.

CityMetric is now City Monitor, a name that reflects both a ramping up of our ambitions as well as our membership in a network of like-minded publications from New Statesman Media Group. Our new site is now live in beta, so please visit us there going forward. Here’s what CityMetric readers should know about this exciting transition.  

Regular CityMetric readers may have already noticed a few changes around here since the spring. CityMetric’s beloved founding editor, Jonn Elledge, has moved on to some new adventures, and a new team has formed to take the site into the future. It’s led by yours truly – I’m Sommer Mathis, the editor-in-chief of City Monitor. Hello!

My background includes having served as the founding editor of CityLab, editor-in-chief of Atlas Obscura, and editor-in-chief of DCist, a local news publication in the District of Columbia. I’ve been reporting on and writing about cities in one way or another for the past 15 years. To me, there is no more important story in the world right now than how cities are changing and adapting to an increasingly challenging global landscape. The majority of the world’s population lives in cities, and if we’re ever going to be able to tackle the most pressing issues currently facing our planet – the climate emergency, rising inequality, the Covid-19 pandemic ­­­– cities are going to have to lead the way.

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The City Monitor team is made up of some of the most experienced urban policy journalists in the world. Our managing editor is Adam Sneed, also a CityLab alum where he served as a senior associate editor. Before that he was a technology reporter at Politico. Allison Arieff is City Monitor’s senior editor. She was previously editorial director of the urban planning and policy think tank SPUR, as well as a contributing columnist for The New York Times. Staff writer Jake Blumgart most recently covered development, housing and politics for WHYY, the local public radio station in Philadelphia. And our data reporter is Alexandra Kanik, whose previous roles include data reporting for Louisville Public Media in Kentucky and PublicSource in Pittsburgh, Pennsylvania.

Our team will continue to grow in the coming weeks, and we’ll also be collaborating closely with our editorial colleagues across New Statesman Media Group. In fact, we’re launching a whole network of new publications, covering topics such as the clean energy transition, foreign direct investment, technology, banks and more. Many of these sectors will frequently overlap with our cities coverage, and a key part of our plan is make the most of the expertise that all of these newsrooms combined will bring to bear on our journalism.

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As for CityMetric, some of its archives have already been moved over to the new website, and the rest will follow not long after. If you’re looking for a favourite piece from CityMetric’s past, for a time you’ll still be able to find it here, but before long the whole archive will move over to City Monitor.

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Sommer Mathis is editor-in-chief of City Monitor.