#3 TSL: What If Humans Are No Longer Among the Living?
Explore thought experiments about Earth 2.0. Ask yourself the title question and join me in the comments for a deep dive. Let’s create a shared vision and discover alternatives worth fighting for.
#3 Thought Seeds Lab
“We need to remember that we are one species among many, a species that is no more or less special than the shimmering hairy protist that lives inside the termite gut, the rhinoceros botfly, or a ground beetle species that lives its entire life among the leaves of a single individual of a single species of Panamanian tree.”
- Rob Dunn
Rob Dunn's ego-shattering words hit me in the face at first, but then left me smiling. I couldn’t help but kick off this topic with that quote. To understand this post-human world, we must first recognize our small place in the grand evolutionary tree of life.
The Extinction of Humans and Our Small Place Among All Species
An evolutionary tree of life that includes all the major branches of life (but not all species!). On this tree, or rather, a sort of bush, each line represents a major lineage of life. All species with cells with nuclei are part of the Eukaryotes, represented as a single broom-like branch, indicated by an arrow, in the lower right-hand section of the tree. Eukaryotes include malaria parasites, algae, plants, and animals, among other life-forms. The Opisthokonta, one small part of the Eukaryote branch, is the branch that includes animals and fungi. Animals, if we zero in, are just one slender branch of the Opisthokonta. From this broad perspective, vertebrates do not get a special branch on the tree. The vertebrates are a small bud. The mammals are a cell in that bud. Humanity is, to continue the metaphor, something less than a cell. (A Natural History of the Future, Rob Dunn)
Now imagine this: We live in a period of geological time identifiable by the fossils not just of individual—or groups of—animals but of entire cities.The Economist:
The most common way of distinguishing periods of geological time is by means of the fossils they contain. On this basis picking out the Anthropocene in the rocks of days to come will be pretty easy. Cities will make particularly distinctive fossils. A city on a fast-sinking river delta (and fast- sinking deltas, undermined by the pumping of groundwater and starved of sediment by dams upstream, are common Anthropocene environments) could spend millions of years buried and still, when eventually uncovered, reveal through its crushed structures and weird mixtures of materials that it is unlike anything else in the geological record.
With all this, we have an incredible power of influence. In 1778, the French naturalist Buffon wrote, "The entire face of the Earth bears the imprint of human power."
Our family, the Hominidae, evolved around 17 million years ago, during a time when the major branches of the tree of life had already existed for hundreds of millions, if not billions, of years. These branches survived various changes, including those triggered by meteor impacts and volcanic eruptions. Early hominids, evolving in a world with oxygen levels similar to today but slightly higher carbon dioxide levels and temperatures, found favorable conditions.
As Homo erectus emerged around 1.9 million years ago, environmental conditions were much like today, possibly cooler. Our bodies have adapted to what we now consider "normal" conditions, but these are actually quite unusual. The more we alter Earth, the less suitable it becomes for our survival. While we may find ways to adapt in the short term, eventually, our species will face extinction, as do all species. The average lifespan of an animal species is about two million years, and Homo sapiens, having evolved around 200,000 years ago, still has time but is also prone to extinction due to its youth and potential for fatal errors.
It is crucial to remember that sudden climate change was a significant factor in the extinction of Neanderthals, who shared many similarities with Homo sapiens. Neanderthals were highly adapted to the cold climates of the Ice Age, and as the climate shifted rapidly, they struggled to adapt to the new environmental conditions and dwindling food sources.
Imagine a world where humans have vanished. One morning the sun rises, nature wakes up but people do not wake up, there is no sound of vehicles, no one is in a hurry to go to work and fills the subways...
Which Species Will Go Extinct After Humans and Why?
Now, let's dive deeper into this post-human world. As we fade into history, many species that have coexisted with us will also face their demise. This phenomenon, known as co-extinction, occurs when species that rely on another for survival disappear as their host species does. Humans, supporting thousands of dependent species, are exceptional in this regard.
Consider the organisms that live with us: German cockroaches, dust mites, bed bugs, and sewer rats. While they survive our attempts to eradicate them and thrive alongside us, their fate will change in our absence. German cockroaches may face co-extinction, bed bugs will become rare, and species dependent on our waste, like certain ants and sparrows, will decline.
Humans host numerous beneficial gut bacteria, skin bacteria, and unique viruses. When we vanish, so will many of these microorganisms.
There may be other competitors in the world's best mansion competition, but if there are, I don't know what they are.
- Rob Dunn
Outside our bodies, our domesticated plants and animals will also suffer. Hundreds of plant varieties cultivated by humans will disappear without our care, and the microbes that help them grow will likely be extinct. Farm animals, pets like chickens, cows, and potentially dogs, will struggle to survive without human support.
Imagine abandoned farmlands, once vibrant with crops, now overtaken by wild plants. The intricate dance between crops and their symbiotic microbes will cease. Our agricultural legacy, the thousands of plant varieties we cultivated, stored in places like the Svalbard Global Seed Vault, will eventually degrade without human intervention, leading to the extinction of many unique plant species and their associated microbes.
Which Species Might Emerge, Thrive, or Dominate After Humans?
Here, it may be useful to look at Chernobyl to examine the aftermath of human errors. The truth is, with or without us, the natural world will rebuild. In the 30 years since the evacuation of Chernobyl the wild has reclaimed the space. Today, the forest has taken over the city. The living world will endure. We humans cannot presume the same.
Yet, life will find a way to thrive anew. Picture a world slowly being reclaimed by nature. Forests expanding over cities, wildlife exploring once-human domains.
After we go extinct, and after the last cow falls, life will be reborn from what is left. The species that remain will, as Alan Weisman put it in his book The World Without Us,“sigh a huge biological sigh of relief.” After the sigh, some features of the rebirth of Earth are predictable. The life that remains will be reshaped by natural selection into a diversity of new and wondrous forms. On some level, the details of those forms are unknowable, yet we do know that they will still obey life’s laws. While the specifics are unknown, certain patterns and principles of evolution will continue to apply.
Following a mass extinction, new forms don't necessarily mirror the old. For instance, after trilobites, no similar species re-emerged, nor did giant herbivorous dinosaurs return. However, familiar evolutionary themes recur, as seen in the repeated evolution of similar traits in different species facing similar environmental challenges.
Some species will thrive in our absence, especially those already adapted to harsh conditions. Extremophiles, bacteria, and fungi resilient to extreme temperatures and radiation may become dominant. In warmer climates, smaller-bodied animals may evolve, while larger bodies might develop in colder environments, following Bergmann's rule.
A group of evolutionary biologists might predict that life will generally trend towards greater diversity, variability, and complexity. Surviving species, like certain wild cats or dogs, may diversify into numerous new species. For example, from a few surviving foxes, multiple new fox species might evolve, each adapted to specific niches.
As conditions change, new evolutionary paths will open, leading to adaptations we can't predict. Some themes will echo the past, while others will forge entirely new directions. Just as past environments shaped unique creatures, future conditions will do the same, creating a world where life continues to evolve in remarkable and unforeseen ways.
Humans are not evil: Neither Fully Natural nor Entirely Separate from Nature
I want to underline this. We did not do this because we are evil. Humans is not fully natural. The mathematical interpretation of nature denies the essence of life, underlying the "irresistible dynamic" that enables economic rationality to exploit all aspects of life. Humans are both part of nature and distinct from it. The idea of human harmony with nature did not emerge in the West until at least the late modern period. Both humans and animals have never lived in peace with nature. Nature is not serene; it maintains balance and reproduction through the interactions and counteractions of countless subsystems.
Human dominance over nature began with settlement and the development of effective tools. The notion that human intervention in natural processes is inherently evil, or that we must treat "benevolent Mother Nature" with care, is foolish. All living beings struggle with nature by their very essence. They consume, are consumed, and conquer each other. They all impact their environment, altering it as they extract resources. What sets humans apart is our limitless capacity for learning. By nature, humans are not inherently natural. Only through socialization do humans become fully realized beings. Without socialization, natural, inherent capacity does not exist.
Humans are not genetically programmed to live in harmony with their environment. Unlike other species, humans must self-impose restrictions on certain interventions in natural cycles to align their way of life with the integrity of nature.
As Sartre said, humans are "condemned to be free." Only humans can limit themselves in a way that does not instrumentalize or destroy their unique nature. While animals are bound by instinct, humans can, through wisdom, impose self-restrictions to live in harmony with nature—a task befitting the modern human who has bitten into the apple of knowledge, independence, freedom, and human rights.
As we ponder a world without humans, we are reminded of our small yet significant role in the vast web of life. The Earth will continue to evolve and adapt, with new species rising and others falling in our absence.
“The Road to Earth 2.0” is not just about imagining a future without us, but about understanding the potential for renewal and resilience in nature.
Join me as we continue to sow these thought seeds, imagining the vibrant tapestry of life that could unfold in the post-human world.
The future may be uncertain, but it's sure to be fascinating.
A Special Thanks to Rob Dunn
I want to give a special thanks to Rob Dunn. His work has been instrumental in shaping my understanding of our place in the natural world. I used a lot of information and ideas from his book "A Natural History of the Future," which provided invaluable insights into the complex relationships between species and the potential futures of life on Earth.I highly recommend his work to anyone interested in understanding the intricate dance of life that continues, with or without us.
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The World Without Us is an amazing book
This is a great article!
I’ve always found nature’s ability to reclaim abandoned or obliterated places to be so beautiful — it brings me a sense of strange peace. I think we can learn so much from nature’s adaptability and resilience in the face of disaster.
And yes, of course, if we continue on the path we’re on, we’ll disappear and the Earth will not. But I hope we can learn to adapt like the earth to the disasters we’ve caused in order to become more resilient a