What If Earth Never Had Humans? | Unveiled

What if Earth Never Had Humans?

Human life has completely changed the planet we live on, affecting everything from the smallest organism to whole climate systems. In an alternate reality, though, life might not have developed in the same way here… So why not take a step back and examine what the world would be like if humans hadn’t been around?

This is Unveiled and today we’re answering the extraordinary question; What if Earth never had humans?

There’s little doubt that humans have had a huge impact on “how the world works” for thousands of years, reaching all the way back to the extinctions debatably caused by humanity at the end of the last ice age. Huge numbers of species disappeared at that time, around ten thousand years ago, just when humans began to spread around the planet... with some pitching the “overkill hypothesis” as to why so many large animals died out; the idea being that they were hunted to extinction by humans.

But “humans”, in a broad sense, have been around for much longer than even that… and the direct ancestor of all branches of the human family (or homo genus), the Australopithecus, dates back close to four million years. Modern humans, or homo sapiens, along with Neanderthals, homo erectus, and a number of other branches of now extinct varieties of human all evolved from Australopithecus. While all these species undoubtedly altered the world around them, prompting various changes to affect the course of history, modern humans have absolutely reshaped Earth in a relatively short period of time. From the physical structures we’ve built, to the more indirect ways we’ve altered the destinies of other species… in many ways the world is what we’ve made it; for better and worse.

Human effects on the climate are one of the most widely debated and prominent issues today. Whether it’s global warming, ocean acidification, deforestation, or a number of other environmental concerns, it’s easy to see the hand of humanity when considering climate change. A multitude of scientific studies now suggest that human society is the cause of a rapid increase in global temperatures in the past few centuries. Since the industrial revolution, in particular, the atmosphere’s been clogged by CO2 and greenhouse gasses, to the point that human behaviour (now and in the past) is today melting glaciers, diminishing ice sheets and causing sea levels to rise. Of course, there are other, non-human causes for global warming, but the growing majority of scientists argue that natural climate change is not what we’re seeing now. Add into the equation that humans have also created new and unnatural materials, like plastics - the majority of which are non-biodegradable and stay trapped in ecosystems for years - and we can start to see just how much of a difference one species can make.

Naturally, it isn’t just the Earth itself that has been affected by humanity, either… but also the other species that share this world with us. Safe and reliable shelter is one of the most primal human needs… and, so, entire landscapes have been reshaped and replaced by villages, towns and ever-expanding cites over the centuries. But lest we forget that “safe and reliable shelter” is a basic need for all other life, as well… and the erecting of human settlements has often come via deforestation and general urbanisation. Today, worldwide loss of biodiversity is one of our most pressing ecological problems… so much so that plenty of scientists, analysts and environmentalists argue that we’re already in the midst of the next mass extinction; the Holocene Extinction. No one’s yet sure exactly how many species will disappear during it, but it is reportedly causing the rate of extinction to be between one hundred and one thousand times what’s normal!

It’s not all “take, take, take’, however. While many species have disappeared, humanity has created a number of new ones as well. Through farming and domestication, everything from corn to various species of dog has been selectively grown or bred by humans. So, if Earth had never had humans, then it’s other crops and creatures might well have evolved differently, too. Taking the development of farm produce as an example, the emergence of new types of carrot, apple or anything else can take decades or centuries in the natural order of things. But, humans can and have fast-tracked the process innumerable times, via genetically modified organisms (or GMOs) - a supposedly efficient but certainly controversial method of growing.

Humans are also partly responsible for where other flora and fauna species live, too, with human travellers and settlers introducing non-native animal and plant populations to new habitats all across the planet - sometimes intentionally, sometimes accidentally. It’s another way in which human actions shape the rest of life on Earth, particularly when an invasive species has no natural predators or limiters wherever it’s been moved to - as was the case with the cane toad in Australia, or with the kudzu vine in the American south. Time and again we’ve seen humans introduce a new species to a new region, only for it to grow and thrive at an uncontrollable rate, sometimes even enforcing the extinction of other, native crops and creatures. For many, it’s just another unsettling aspect of the ongoing Holocene Event.

According to a 2015 study by Denmark’s Aarhus University, though, it isn’t what humans bring with them that’s shaping the spread of biodiversity; it’s the humans themselves. In trying to answer why certain geographical regions - like the Serengeti, for example - hold a much wider than average variety of large mammals, the study argues that it’s because these are the only places left where humans haven’t yet eradicated endemic species. These rare locations on the world map have been relatively unchanged throughout human history, compared to most of Europe, for example. But, while we might think that particular animals have simply evolved to live in dusty savannahs (or in any other inaccessible region)… the Aarhus report suggests that one of the main reasons a brown bear, for instance, lives mainly in the mountains is because that’s where it has needed to go to evade human settlements. Whether the risk is hunting or habitat destruction, certain animals just inherently know to stay away from people. If, then, humanity had never been around, it’s thought that large animals like lions and elephants would now exist all across the globe, instead of only in specific regions.

And, perhaps unsurprisingly, there’d be plenty more trees around the place, as well. According to estimates, of the six million square miles of rainforest that once existed on Earth, less than forty percent of it still exists… with human-led deforestation to blame for much of the loss. While we are beginning to readdress the balance with various tree-planting initiatives around the world, the thousands of years’ worth of repurposing trees for our own need has no doubt fundamentally changed the planet.

Despite all of that, though, it’s not all bad, and humans have and do affect Earth in a positive way, too. Regarding extinctions themselves, twenty-first century humans have developed technology to predict certain cataclysmic events, and in some cases even prevent natural disasters. Some of the vast and deadly catastrophes of the past might now, in some cases, be averted, or at least lessened. On the one hand, human knowledge has bred flood defences, firefighting techniques against forest fires, and seismometers to warn of tsunamis; on the other, efforts are ongoing to develop tech that could even save the world from an extinction level crisis like an asteroid strike. So, if Earth never had humans, then it wouldn’t today have a means to detect and potentially avoid these threats to it. More so than any other species, humans have the capability to understand “how Earth works”, and therefore to ensure that it carries on working.

There are a number of ways that humans are preparing the planet for a potentially inevitable world-ending event, too. In fact, it’s thanks to human actions that a higher percentage of life could well survive, if Earth were to suffer an extinction similar to what happened to the dinosaurs. There’s the Svalbard Global Seed Vault, on the Norwegian island of Spitsbergen, built to prevent plant species from being lost forever post-apocalypse. We’ve also created numerous “frozen zoos”, where the genetic materials for countless animals are stored and preserved.

And then, there are the monuments we’ve built for ourselves, whether at the expense of nature or not, which could also serve as a reminder of what Earth was, following disaster. From the Greatest of Pyramids to the tiniest of houses; the largest of cities, to the smallest of villages; from the simple wheel to the probes we’ve sent all across the solar system… they’re the marks of human civilization that would otherwise never have occurred.

Clearly, humans possess a unique environmental influence. Knowingly or not, we’ve been a big reason why Earth is today the way it is. Without humans, this planet might’ve looked, sounded, even smelled like a totally different place by now. But, equally, while our species has had an untold impact on the past, we also have the chance to affect the future - for the good of the world or to its detriment. Time will tell which route we take.