Part 1: Home on Earth
‘Eco’ comes from the ancient Greek word ‘oikos’.
Oikos refers to three related but distinct concepts: the family, the family’s property, and the house.
Simply put, eco = home.
‘System’ comes from the ancient Greek word ‘systema’
Systema is the concept of an organized whole in which the whole is compounded of parts.
A system is the way in which all the elements of something function together..
Thus, an ecosystem is the way in which a home functions.
When we’re talking about life, and especially life on Earth, ‘ecosystem’ has a particular definition :
An ecosystem’s mainspring is energy flow through several trophic levels, ensuring the transformation or transmutation of material from one state to another. Thus a food chain consists of several relays, whereby nonliving matter (ie, gaseous, liquid or solid) is turned into living tissues by plants; the latter are digested by herbivorous or phytophagous (ie, insects) animals, which in turn are consumed by carnivores, which may undergo predation by yet other carnivores. — Reference
The Earth itself is just the location for biomes and ecosystems — nature’s neighborhoods and homes. And, like any place where we build a society — neighborhoods can evolve drastically and homes can be built or demolished.
The different ecosystem homes on Earth are not completely independent : they are linked by a number of factors including shared abiotic resources, species migration, and competition for biotic resources so that the change of one impacts a few, the change of many impacts many more, and failure of many through destruction or insufficiency can result in a cascade failure that causes most of the others to fail as well.
250 million years ago, Earth had biome neighborhoods of ecosystem homes supporting ferns and conifers and ginkoes, and trilobites, dimentrodons, and orthacanthi. Some of these ecosystem homes that had persisted for hundreds of millions of years. When prolonged volcanic activity happened in what is now Siberia, the environment shifted and the ecosystems that existed then got into a death spiral, each putting out too much of this or too little of that until they stopped working together as a whole and the ecosphere was dramatically altered. 95% of Earth’s life in the oceans and 70% on land was wiped out and it took another 5 million years for the before migrating animals to emerge again and 50 million years for a new underlying ecosystem of flora and fauna to fill the world.
85 million years ago, Earth finally had developed biome neighborhoods of ecosystem homes supporting the flowering plants, insects, placental mammals — precursors to a modern human diet. New dinosaurs roamed the land with the fearsome Tyrannosaurus rex among them. 20 million years later, however, most of these ecosystems had collapsed. A global catastrophe occurred, and the skies were filled with clouds, smoke, and dust, keeping the sun’s light away from Earth for years. Vegetation died out and ecosystems failed, resulting in 70% of ocean species and 15% of land species going extinct. No species of land animal weighing more than 50 pounds survived. It was the end of large dinosaurs. The new ecosystems that emerged from the catastrophe weren’t able to support large animals — only small animals survived. The last remaining remnant of the dinosaurs are birds. Large dinosaurs never recovered and they no longer have a home on Earth.
Simply put, an ecosystem is a home on Earth in which some life harvests the energy of the sun, other life eats that life, and so on and so forth until a mutually sustaining web of life is created.
On a larger scale, Earth has biomes. Each biome has a distinct environment that decides the types of plants and animals found there — freshwater lakes, grasslands, boreal forests, and deserts are all examples of biomes. Biomes are the ecological equivalent of neighborhoods with a variety of ecosystems with similar species.
Some of Earth’s current biomes have ecosystems that include humans. Humans are able to live on grasslands and forests, at the edge of the ocean or in the vegetative parts of the desert. Others do not. Humans cannot naturally live in the depths of the ocean, in the midst of a non-vegetative desert, deep in caves, nor on barren ice-locked land away from the ocean’s edge.
While humans can travel to these places, they cannot sustain themselves in them without supplies from other ecosystems. Humans need fresh water sources that are more consistent than rain, a source of food that is edible to humans, and the ability to create shelter and clothing to regulate our body temperatures.
To make a distinction between all of Earth’s ecosystems and the subset of ecosystems those that support human life. Let’s call an ecosystem that includes humans in its natural state a human ecosystem — a home for humans on Earth — and a biome that supports these ecosystems a human biome — a neighborhood for human ecosystems.
Collectively Earths’s biomes and ecosystems are called an ecosphere. Earth has had many different ecospheres — different global conditions that have supported wildly different life.
600 million years ago, Earth had neighborhoods of ecosystems supporting algae and flagellates… a fantastic home for them but if we jumped in a time machine and visited it, this ecosphere wouldn’t have enough oxygen for humans.
250 million years ago, Earth had neighborhoods of ecosystems supporting ferns and conifers and ginkoes, and trilobites, dimentrodons, and orthacanthi. If this ecosphere returned, humans could move in — but not too many — those that would live there would need to survive off of pine nuts, a few tubers, and cockroaches. Most life in this ecosphere isn’t edible to humans.
150 million years ago, Earth had neighborhoods of ecosystems supporting stegosaurs, archaeopteryxes, and allosaurs. If this ecosphere returned, humans could live in some regional ecosystems in an ecosphere like this, eating nuts and eggs, cockroaches and small animals, but not as an apex predator on the food chain… humans would be of the ‘tasty snack’ variety to some of the large dinosaurs and other huge carnivores that thrived in those Earth ecosystems.
60 million years ago Earth’s ecosystems were recovering from the Permian-Triassic extinction event that wiped out the last of the large dinosaurs along with 95% of Earth’s life in the oceans and 70% on land. Mammals began to proliferate along with the grasses, flowering plants, and conifers that we see on Earth today. Humans would have done well in this ecosphere — good temperatures and oxygen levels, plenty to eat, and no large predators.
It is important to understand that humans not only live in a variety of ecosystems on Earth, but also within Earth’s current ecosphere — the human ecosphere — that supports the worldwide balance of ecosystems that are habitable to humans.
It is only in the last 130 million years (the last 3% of the age of Earth) that the flowering plants that form the basis of the human diet emerged and the last 2.6 million years (the last 0.06% of the age of Earth) that human ancestors evolved to eat meat. Our human ecosphere is a delicate thing. If our ecosystems collapse we may evolve to eat grass like cows or poisonous berries like birds…or we may not.
There is no guarantee that wiping out the biomes with ecosystems that support humans would result in new ecosystems that humans can adapt to. If we lose our current ecosphere due to environmental catastrophe or ecological collapse and an ecosphere like any of those that existed in the hundreds of millions of years before the human ecosphere took their place, humans wouldn’t be able to survive very well — or at all in most cases.
If we don’t protect this ecosphere and these ecosystems,
humans will no longer have a home on Earth.
There seems to be an enduring fantasy that if we destroy Earth’s current environment and ecosystem, we can simply terraform the Moon or Mars.
