The Anthropocene vs. The Doomed Earth

On Saturday, September 14, 2013, The New York Times published an op-ed by Erle C. Ellis entitled, “Overpopulation Is Not the Problem.”  Professor Ellis challenges the conventional wisdom that the future of the Earth is threatened by an inexorably increasing human population.  He tells us that emerging knowledge of the history of human civilizations should reassure us that humans have altered ecosystems for 200,000 years to meet their needs and there is no reason to believe there is a limit to the ability of humans to continue to manipulate our environment as needed to support a growing population.   


Little of human history is recorded.  Therefore, only recent discoveries of archaeologists have informed us of the many technological advances of human civilization that increased food production.  Irrigation and agriculture, for example, is a relatively recent human accomplishment.  In the Old World, humans have supplemented their diets by raising domestic animals in the past 6,000 years.  This knowledge only reached the New World with Europeans in the 16th century. 

Professor Ellis suggests that our appreciation of human adaptability is based on our knowledge of the history of human accomplishment.   That knowledge is not only relatively new, but is not yet widely known by the public.  He admits that he, himself, did not comprehend human adaptability until studying agriculture in China, where human ingenuity has managed to keep pace with the growth of the most populous country on Earth.  His work is now as informed by archaeology, geography, and economics as it is by his original discipline, biology.

We introduced Professor Ellis (University of Maryland, Baltimore) to our readers in an article about the globalization of ecology by humans.  He is one of the proponents of naming a new geologic era, the Anthropocene, to acknowledge the fact that the activities of humans have altered the Earth in significant and profoundly important ways.  He does not find reason to despair about our impact on the Earth:

“The only limits to creating a planet that future generations will be proud of are our imaginations and our social systems.  In moving toward a better Anthropocene, the environment will be what we make of it.”  (1)

At the opposite extreme:  The viewpoint of Jake Sigg

At the opposite extreme of Ellis’ rosy view of the future of the Earth and its human occupants, we turn to Jake Sigg’s “Nature News.”  Regular readers of “Nature News” will find the following example of Sigg’s pessimistic view of the future of the Earth typical of his viewpoint:

“My vision for the world is increasingly apocalyptic.  Lest you think I’m being overly dramatic, with the type of economic/political system we have, things can only get worse, not better, and the horror and chaos of Syria, Egypt, et al could be easily foreseen–not in detail, but in general, as the result of too many competing for space and resources.  I expect lots of horror stories in the future, and I hope I’m dead by the time it hits me directly.  At the pace things are moving, I may not be that lucky.”  “Nature News,” September 7, 2013.

Jake Sigg’s concern about over-population also motivates his extreme opposition to immigration, including legal immigration. 

Finding Common Ground

As diametrically opposite as these viewpoints seem on the surface, they actually share common ground.  As Professor Ellis says, “The science of human sustenance is inherently a social science.”  In other words, the famines that humans have experienced were as much a failure of the social system as they were of the physical limitations of the planet to provide adequate food.  Jake Sigg agrees that “our economic/political system” is at least partially to blame for the failure to compensate for inadequate resources. 

For example, the current round of climate change has been caused by the activities of humans, but our social, political, and economic systems are preventing us from responding to it effectively.  Hunger in America will be exacerbated if conservative politicians are successful in their effort to drastically reduce the availability of food stamps to the poor.     

Professor Ellis is confident that human social systems will accommodate population increases.  Mr. Sigg predicts the opposite outcome.  The more likely outcome is probably somewhere in between.  We will probably muddle through with occasional catastrophic famines where physical shortages cannot be mitigated by competent social/political structures. 

Admittedly, this topic is a digression for Million Trees.  It is intended as a reminder that the ecological “restorations” being demanded by native plant advocates should be a public policy decision and the failure to treat it as such has resulted in irreparable harm to our environment.  It is therefore an example of how environmental problems and their resolution are ultimately failures of human social systems.

Update:  Our readers might be interested in Jake Sigg’s very different reaction to Erle Ellis’ op-ed in his latest newsletter (September 17, 2013), available here.  Here is an excerpt from it:

“One of the most discouraging developments of our time is the elevation of opinion to equal status with knowledge in the minds of large numbers.  People who have spent their lives studying and working in a field are on equal footing with someone who hadn’t thought about the matter five minutes ago, and their vote counts just as much.  Not exactly a way to build a lasting, self-perpetuating society.”

In other words, problems are caused by too much democracy, in Sigg’s opinion.  He believes that “experts” should be in charge, of which he—a retired gardener in the Recreation and Park Department– is apparently one and Erle Ellis—Associate Professor of geography and environmental systems at University of Maryland, Baltimore—is not.  In contrast, Million Trees values expertise, but considers the alteration of our public parks a political decision which must be made democratically.  More democracy is needed to resolve these conflicts, not less. 


Erle C. Ellis, “Overpopulation Is Not the Problem,” New York Times, September 14, 2013.

Past & Present Botanical Myths

The conventional wisdom is that human knowledge, especially scientific knowledge, moves inexorably forward.  We are sometimes amused by the misconceptions of the past and marvel at the primitive knowledge of our ancestors.  However, we rarely stop to think that our descendents will probably do the same when they consider our current state of knowledge.

Historical botanical beliefs

"The heads of cowslips, which trembled in the wind, were signed for Parkinson's disease, the 'shaking palsy.'" (1)

The Doctrine of Signatures seemed a logical botanical belief at a time when plants were one of man’s few medicinal tools and religion was a powerful influence in human society.  The Doctrine of Signatures, which was actively promoted by the church in 17th century Europe, was based on a belief that God had “signed” plants with certain suggestive shapes and colors to inform humans of their medicinal properties.  For example, a heart-shaped leaf was considered God’s message to us that a particular plant would be beneficial to the human heart and this message was strengthened by a flesh-colored flower. Every plant was believed to be useful in some way if man could only discern its use.  Else why would they have been created, since the Garden of Eden was created for the benefit of man?  The church encouraged man’s study of plants as a way to worship God’s creation. (1)

Many botanical myths originated from ancient Roman and Greek horticultural treatises and persisted for hundreds of years.  For example a belief in the influence of the moon on plants is first found in the writings of Pliny in first-century Rome and also found in writings as late as 1693:  “[w]hen you sow to have double Flowers, do it in the Full of the Moon.”  (2) 

The origins of many horticultural myths are unfathomable but probably began with a particular event because we often confuse coincidence with causal relationships. (2)

  • Planting bay trees and beeches near  homes will prevent lightning strikes
  • An apple tree that fruits and flowers at the same time is a bad omen
  • The parents of a child who picks red campion will die
  • A pregnant woman who steps over cyclamen will miscarry

Modern botanical beliefs

Now we will turn to the theoretical underpinnings of the native plant movement to see how they are holding up to the scrutiny of current science and ask the rhetorical question, Is it time to relegate invasion biology to the dust heap of discredited science?

The field of invasion biology upon which the modern native plant movement is based, originates with the publication in 1958 of The Ecology of Invasions for Animals and Plants by Charles Elton.  Elton postulated that every plant and animal occupies a different ecological “niche” and plays a specific role within that niche: 

“…every species will have a slightly different role, or niche, and often, he believed, every niche will be filled.  Some animals eat grass, others leaves; some plants grow on wet soil and some grow on dry; some birds nest in dead trees, others in live ones.  When new species are introduced, the theory goes, they can get a foothold and start reproducing only by finding a vacant niche or by throwing some other species out of its niche…” (3)

Elton’s corollary to the exclusivity of the niche is that the introduced species will have a competitive advantage because its predators are absent in its new home.  The predicted result of Elton’s theory was that introduced species will exterminate previous occupants, mass extinctions will occur, and the result will be a simplified ecology composed of few surviving species.

The problem with Elton’s theory is that it doesn’t correspond with reality.  More and more scientists are finding that the frequency of introductions far exceeds the frequency of extinctions.

  • In 2002 Dov Sax reported that introduced species greatly outnumbered extinctions on oceanic islands:  “In the case of plants, islands are now twice as diverse as they were before humans started moving things around.” (3)
  • In 2012, Erle Ellis, et. al., reported that “…while native losses are likely significant across at least half of Earth’s ice free land, model predictions indicate that plant species richness has increased overall in most regional landscapes, mostly because species invasions tend to exceed native losses.” (4)
  • In San Francisco, the second-most densely populated city in the US, ninety-seven percent of the 714 plant species known to exist in San Francisco in 1850 are still found there, despite the fact that most plants and trees in the city are introduced.  (5)

The dire predictions of invasion biology have not come to pass nearly 60 years after their inception.   Many scientists are clearly ready to abandon invasion biology because it does not conform to reality.  Can we finally breathe a collective sigh of relief and move on to a less gloomy view of ecology?  Some day our descendents will look upon this episode in human history and laugh, as we laugh at the 17th century Europeans who examined plants, looking for the clues from God that revealed their purpose.


(1) Richard Mabey, Weeds:  In Defense of Nature’s Most Unloved Plants, Profile Books Ltd, London, 2010, page 87-91

(2) Andrea Wulff, The Brother Gardeners, Alfred Knopf, 2008, page 11-12

(3) Emma Marris, The Rambunctious Garden, Bloomsbury, USA, 2011, page 102-104

(4) Erle C. Ellis, et. al., “All Is Not Loss:  Plant Biodiversity in the Anthropocene,”

(5) Duncan et al, “Plant traits and extinction in urban areas:  a meta-analysis of 11 cities,” Global Ecology and Biogeography, July 2011

The Globalization of Ecology by Humans

Humans have had a profound impact on our planet wherever they have lived.  Since the industrial age man’s impact on the environment has even extended beyond where he lives as atmospheric changes impact remote places such as the polar regions. Humans are a particularly restless species of animal, forever fleeing whatever conditions threaten existence or seeking a better life ahead.  Because we are an adaptable species with the capacity to alter conditions, we have a wider range of movement than other animals. 

Wherever humans have gone they have taken with them the seeds of plants, at first unwittingly and then purposefully after the advent of agriculture.  Edward Salisbury, a 19th Century British horticulturalist, reported raising 300 plants of 80 different species from the debris in his trouser cuffs despite wearing spats.(1)

The impact of Native Americans on the landscape

Native Americans arrived in North America about 13,000 years ago and slowly migrated to South America.   The megafauna that Native Americans found when they arrived disappeared soon after they arrived.  Although not all scientists agree, there is strong evidence that the megafauna, such as enormous buffalo and mastodons were hunted to extinction by the first human inhabitants of the New World.  The loss of these huge herbivores was a factor in the development of grasslands that were not adapted to heavy grazing.(2)

Native Americans setting grass fire, painting by Frederic Remington, 1908

The most profound alteration of the ecology of the New World by Native Americans was their use of fire to assist their hunting and gathering activities.  Burning grassland to the ground encourages the growth of new sprouts that improve grazing and attract the animals the Native Americans hunted.  And burning grassland funneled the animals into the hunt.  These frequent burns prevented the succession of grassland to shrubs and forest, maintaining prairies that were essentially manmade. 

The arrival of Europeans in the New World

This process of transplanting plants around the globe was greatly accelerated by the age of exploration which began in earnest in the 15th century.  When Columbus arrived in the New World in 1492, he found a land that had already been radically altered by Native Americans, though he had no way of knowing that. 

The Europeans that eventually settled the New World were ignorant of the impact of Native Americans on their new home until the advent of archaeology in the 20th century.  Their ignorance was based on their mistaken perception that the Native American population was small.(3) 

In fact, the population of Native Americans was decimated by the time the Europeans settled the New World nearly 200 years after the early explorers arrived at the end of the 15th century.  The early explorers introduced European diseases to which they were immune, but the Native Americans were not.  From just a few localized contacts with Europeans these diseases–such as measles, smallpox, and syphilis–spread quickly through Native American communities, sometimes reducing the population by as much as 90%.  These deadly epidemics were largely unwitnessed by the tiny population of early explorers.

Alfred Crosby speculates in Ecological Imperialism that Native Americans were particularly vulnerable to these diseases because they had virtually no domesticated animals.  He gives us a fascinating explanation of how Europeans developed their immunities by living in close proximity with animals for centuries.

The history of Native Americans was initially recorded by the European settlers who arrived in numbers nearly 200 years after initial contact in the 15th century.  Their perception that they found a pristine wilderness, largely untouched by human hands, has persisted to this day in the public’s mind.   It is that perception that has led native plant advocates to the conclusion that the pre-European landscape should be the goal of restorations.

The impact of Europeans on the landscape

As much impact as Native Americans had on our landscape it pales in comparison to that of Europeans.  The importation of domesticated animals—such as cattle, pigs, horses, and sheep—changed the ecology of the New World quickly.  Because the population of early settlers was small and the grazing resources vast, these animals quickly became huge herds of feral animals, roaming places such as the pampas of Argentina and the prairies of the mid-west of North America.  The native grasses were quickly replaced by the non-native grasses spread by these wandering herds. (4)

Herd of sheep, Mono County, CA. Creative Commons

Likewise, the agricultural practices of European settlers have introduced virtually everything we eat today in North America.  Nearly all of our fruits, vegetables, and cereals are not native to North America.  If non-native food were to be banished from California, we would be reduced to a diet of game, acorn mush and a few species of nuts and berries.   The diet of Europeans would be equally impoverished if they lost the potatoes, corn, tomatoes, etc. that came to them from the New World.

USDA photo

The Anthropocene:  The geologic age of humans

The Earth’s ecology is in a constant state of change.  Humans are not the source of much of that change.  The continents shift.  The climate oscillates.  Plants are moved by the wind and tide.  Animals move without the assistance of humans, often taking plants with them.  But change has been accelerated by the restless movements and activities of humans. 

Scientists have recently begun to advocate for the naming of a new geologic era, the Anthropocene.   The Anthropocene would officially acknowledge that the environment has been altered by humans.  Although the beginning of this era is still being debated by scientists, Erle Ellis (University of Maryland, Baltimore) believes that an appropriate beginning would be about 6,000 years ago, when humans domesticated animals. 

Why are we suddenly afraid of change?

Changes in the ecology of North America resulting from the movement of humans have been going on for thousands of years and have greatly accelerated in the last 500 years.  Until very recently, these changes were broadly perceived as improvements.  We enjoy a more varied diet than our ancestors and we are shielded from famine by our access to food from anywhere in the world.  We find the products of the New World useful in other ways, such as the rubber that is essential to transportation.

Suddenly, for little apparent reason, we are afraid of everything new in our environment.  The media is full of panic-stricken reports of alien “invasions.”  Most of these panic attacks eventually prove to be baseless.  The newcomers are eventually absorbed into the landscape or they disappear without a trace.  Or scientists eventually explain that the newcomers are better adapted than their predecessors to the climate, water, and soil conditions created by the activities of man. 

We asked a scientist who advises us occasionally this question:  Since new species of plants and animals have been introduced to our landscape for hundreds, if not thousands of years, why the sudden panic?  His reply was:  “It’s trendy. It’s ‘cutting edge.’ It’s ‘hot.’ It’s…fundable.”   

In the service of a scientific fad that has spread into the popular culture, introduced species of plants and animals are being needlessly destroyed.  Many of these new species are better adapted to present conditions than their predecessors.  Many are essential to our way of life and the animals with which we share the planet. 

(1) Richard Mabey, Weeds:  In Defense of Nature’s Most Unloved Plants, Harper-Collins, 2011

(2) Alfred Crosby, Ecological Imperialism. Cambridge University Press, 2004

(3) Charles Mann, 1491, Random House, 2005

(4) Crosby