Why You Wouldn’t Survive on Earth One Billion Years Ago

The time machine is malfunctioning, and the traveler prepares for an emergency landing. It’s not a question of where he’ll land, but when, and whenever he is, he’ll have to develop a plan to survive. But is there any way a human being can survive a billion years in the past? A survival-minded individual probably has a plan for just about any situation. Talking to your prepper uncle, he’s probably asked some ridiculous questions. What’s your plan for surviving if you’re stranded on a desert island? What about in the middle of the wilderness? The odds are, your answer for that might have been…not wind up in those situations! But for survivalists, the fun is in coming up with a plan. However, there are some situations that are trickier than others. You could be dropped in most places on Earth at the moment and you’d likely survive. But what about in other times? That’s where some serious planning and luck come in – if you’ve got a time machine on hand, of course.

A modern-day traveler would have to be very careful to survive in the distant past. In more modern history, such as several hundred years ago, a person would need to avoid alarming the locals with modern technology or clothes for fear of being labeled a sorcerer and being imprisoned or harmed! And the further you go back, the more challenges you’ll have to face. When you go back before the start of modern man, you’d be faced with a wild world. Among the challenges include beasts that dwarf the size of any predator or prey in today’s world; plant life that might be indigestible to today’s stomachs, and novel viruses and parasites that our immune systems might not be able to handle. And that’s before even looking at the atmosphere, which might have a slightly different composition to the one we know today and could wreak havoc on a person’s immune system. Still, a savvy and careful survivalist might be able to eke out survival based on careful hunting and foraging.

But could anyone survive before the dawn of man, before dinosaurs walked the Earth…a billion years ago? Earth has changed a lot to become the planet we know today. In the early days, before the dawn of life, it was barely even a planet at all – instead being a malleable, growing orb made up of unstable magma that was constantly being hit by objects from space. The temperature of Earth back then made it uninhabitable for organic life, even without mentioning the lack of a breathable atmosphere. It resembled a visit to Venus more than anything. But this era, known as the Hadean Eon, ended around four billion years ago. For the next 1.5 billion years, known as the Archean Eon, a lot of changes happened. The Earth started forming continents, although they shifted around frequently. An atmosphere emerged, but it was mostly composed of volcanic and greenhouse gases – far from breathable. And the very first form of life, the primitive single-celled beings known as prokaryotes, started to emerge in the primordial sea.

And that’s where we come in. Welcome to the Proterozoic Eon, starting around 2.5 billion years ago and continuing for almost two billion years. Its name translates to “Early Life,” and this is where the building blocks of the world we live in emerged. But that doesn’t mean it’s time to go camping. Any human who arrives here will have massive challenges to overcome that could make it impossible for them to live more than a few minutes. But let’s say that this isn’t a crash landing. Let’s say that this is an exploration mission – and our human visitor is coming with enough supplies to explore a foreign planet. Because at this point, that’s exactly what Earth is.

This is the first era where we have actual extensive records of the eon, as the Archean Eon left most of its fossils in the deep water. However, during the Proterozoic Eon, rock deposits were formed in shallower areas, and many remain almost intact from that era. Scientists have been able to develop a full picture of the climate during that time – and one thing that’s clear is that during certain periods, it was brutal. One thing is for sure – if a person had arrived at the very beginning of the period, they would have had a much harder time surviving. Oxygen had not yet begun forming in the air in large quantities, and the planet was going through a “Snowball Earth” period – a massive global ice age, the first of its kind.

And then something interesting happened. The very first forms of life emerged during the Archean eon, but they were simple single-celled organisms deep in the sea. Photosynthesis, the process by which organisms absorb carbon dioxide and release oxygen with the help of light, was occurring, but only in small amounts – meaning the presence of oxygen in the atmosphere was minimal at best. Keeping production of oxygen down, minimal sinks of sulfur and iron were taking up much of the gas and storing it to grow. But those stores of unoxidized minerals weren’t infinite, and they eventually ran out – which allowed oxygen to start building up. It’s believed that oxygen levels in the atmosphere started rising around two billion years ago, allowing life to begin evolving.

So is it time to take off that helmet and take a deep breath? Think again. A higher oxygen level is relative. Cyanobacteria, the dominant form of life now, are releasing oxygen into the oceans, but that’s only managed to get the oxygen level in the atmosphere up to around 2%. By comparison, today’s oxygen concentration in the air we breathe is around 21% – so the low oxygen level in the Proterozoic Era would only give humans a few minutes of air if they were taking shallow breaths, a far more extreme version of what happens to people when they climb to the top of a mountain. So keep that helmet on – and take a look up, because things are very different.

Earth is pretty close to fully formed now, but the planet is still finding its equilibrium. If our intrepid time traveler has a watch, they’ll notice something very surprising. A day on Earth, sunrise to sunrise, is only eighteen hours. That means the Earth is spinning much faster than it does for us. As the planet continues to settle into place, it’ll find its current pace, but right now the structure is still very much in flux. And that definitely applies to the shape of the world. Even today, we’re a water planet, with our continents being more like large islands in the middle of a massive sea. But a billion years ago, this was even clearer – because the primordial sea that was the source of all life only had one island in it.

This wasn’t Pangea, the famous supercontinent that was home to the dinosaurs. This was a much earlier supercontinent, Rodinia, that assembled 1.25 billion years ago and continued accumulating landmass for almost half a billion years. This was part of a process that began when a previous supercontinent broke up, and it’s believed that this was a relatively unstable continent – with the connections between many fragments being tenuous at best. This is the earliest supercontinent that we have concrete reconstructions of, and it was surrounded by a superocean named Mirovia. And it was in this ocean where things started happening.

Now, let’s say that our traveler has their basic needs taken care of. They have an oxygen supply so they don’t need to worry about the Earth’s extremely thin atmosphere, and the protective gear can shield them from the environment. The sun at this point in the Earth’s history is much cooler than it is for us – and the Earth’s climate has shifted dramatically. While for a while, the atmosphere made Earth much hotter than it is today due to the heavy presence of greenhouse gases. But as oxygen levels increased, and many of the previous single-celled bacteria that were emitting greenhouse gases died off, the temperature dropped – dramatically. It’s believed that this “Great Oxidation Event,” which led to the conditions that made complex life on Earth possible, led to a drop in temperatures that made the warmest areas of Earth roughly equivalent to the current temperature of Antarctica. Survivable – but not for long.

A billion years ago, Earth was not in a “snowball earth” period, but anyone who’s gone to a place up north in the dead of winter knows that this doesn’t mean it’s possible to spend a long time outside. And few of those locations have temperatures akin to Antarctica. Most of Earth is even colder than that, which means that the threat of frostbite and hypothermia would be a constant presence. A visitor would likely need a climate-controlled suit to survive on Earth for any length of time. And remember – there is no escape! A big part of what makes surviving on Earth a billion years ago so challenging is that there are none of the elements we’ve come to take for granted. When it’s too hot or cold out, we run into the nearest climate-controlled building. Well, none of those around here – unless the time ship makes for a convenient escape nearby.

But even in the wild, there are usually some escapes. When the sun is beating down, people will head to the nearest tree. When the cold is getting a little too much, it’s time to build a fire with some kindling and huddle around it. Good luck with that here. If there’s one word that describes Earth’s climate during this period, it’s probably “Flat.” The surface of the supercontinent is mostly newly formed surface rock, some less stable than others. Mountains will have begun forming, but they’ll largely be just more rock. You might be able to find some shelter from the elements under a rock shelf, but you won’t find any of the markings of a modern-day ecosystem yet. Forget about finding shelter under a shady tree – you won’t even find any leaves. Because plants haven’t evolved yet.

There’s life on Earth when you arrive, but that’s a bit of a deceptive description. There might be other organisms around you – but you won’t be seeing them. That’s because the vast majority of life on Earth at the moment is single-celled organisms and primitive plants, many of which are too tiny to be seen with the human eye. And most, but not all of them are found in the ocean. At first, scientists believed there were no multicellular organisms on Earth and nothing on land at this point, but that’s no longer thought to be the case. Rather, there’s evidence of sexual reproduction among eukaryotes, as well as plant organisms like algae moving onto land. It’s also believed there were some primitive fungi on the land at this point. All this means is that you should keep that hunting gear in the time ship. Food supplies on Earth at this point would be near-nonexistent for any human. It’s possible that some traces of algae would be found on the surface level if large colonies were formed. A person stranded there could theoretically scrape them up and see if they were edible, but the odds are that the answer would be a resounding no, followed by some intense intestinal distress. Algae are rarely edible and can bring the risk of severe food poisoning in the modern day, and it’s impossible to guess just how prehistoric algae or fungi would interact with the modern digestive system. And even if you did find enough algae, the process needed to collect enough for survival would be incredibly difficult and time-consuming. Hopefully, you have enough protein bars in the time ship.

But what about the oceans? Are they the key to life? These prehistoric oceans are where complex life first emerged, with them playing host to the earliest apex predators – including a massive sea scorpion that could prey on anything around it and could grow up to six feet in length. With its fierce claws, it would make a powerful foe for an ambitious fisherman – and would probably also taste delicious when steamed and served with drawn butter. But get those thoughts of seafood out of your head – these beasts are a long time away from where you are now. About half a billion years away. At this time, the primordial ocean is mostly a DNA stew, containing fast-evolving single-celled molecules and primitive plants that are evolving more and more by the century. Even if you stick a fishing net in there now, you’re coming up empty. Similar to scraping up algae and fungi on land, the only thing you’d pick up while trawling the ocean a billion years ago is a complex mix of primitive plants and single-celled organisms that are in the process of evolving. You certainly wouldn’t get any nutrition out of them, and if you collected enough, the odds are you would be introducing some seriously toxic elements into your digestive system. Food would be one of the biggest challenges facing any arrival on this ancient planet.

But what about a far more pressing need? A human being can live without food for several weeks, with severe weakening happening after a month, and death usually coming in about two months at most. But we aren’t so lucky when it comes to water. Dehydration comes on quickly and has serious consequences for anyone who is deprived of water. The “rule of three” says that a person can live three minutes without air, three weeks without food, and three days without water, but none of those are absolute and depend heavily on the climate. What’s clear is that even a few days without water will have devastating impacts on the body, including permanent damage to the organs, and it’s impossible to survive more than a week without water in the best of circumstances. But at least there’s water on the primordial Earth…right? Much like our world, just because there’s water all around you doesn’t mean you have something to drink. That’s definitely been the case for many a shipwreck survivor who broke down and drank ocean water – only to wind up worse than they started due to ingesting a mouthful of saltwater.

But what was the Earth like a billion years ago in the primordial soup of the mega-ocean? The seawater of the era would be much more complicated in chemical composition due to how active it was with microbes, and drinking it would have the same risks as trying to fish from it. Anyone who wanted to drink it would need a very good water filter. Fresh water would only be available in very limited amounts from precipitation, but due to the composition of the atmosphere, it’s impossible to know exactly what it would be like. Impossible…or maybe not. Believe it or not, we do have an idea of what water from a billion years ago tasted like! Back in 2013, a paper in Nature Magazine revealed that water trapped under the surface of Canada, 1.5 miles below ground, had been discovered. This was believed to be the oldest isolated water reservoir ever discovered, and it was so old that dating it was a matter of guesswork – but they knew it was at least a billion years old and maybe twice that. That means it had been isolated as much as half the time Earth existed – and now it was being tested for the first time. Scientists have been able to analyze it as best they could, and then they did the only thing they could in the name of science. Bottoms up! One of the scientists involved was the lucky one who got to take a sip of the water. And surprise, surprise – it tasted terrible! She described it as much saltier than seawater, as well as having a different consistency than today’s water. It almost felt like a light maple syrup and turned a menacing orange color when it made contact with oxygen. This is because of the high mineral content in it, particularly iron. It’s not clear if the long isolation affected it, but if this is a representation of what water was like back then, the odds are no one’s getting a cool glass of water from a billion-year-old Earth.

So let’s look at a tale of the tape. Could a human survive on Earth a billion years ago? The question is…with what? Earth back then had few to none of the building blocks of what we need to survive. The atmosphere was breathable – but only for a few minutes, as the lack of oxygen would quickly lead to unconsciousness followed by death. The water on Earth at the time wasn’t potable, and the only fresh water available was likely extremely limited. There was neither plant nor animal life, which meant no food supply. The climate, while it was starting to resemble our Earth, was likely brutally cold and the weather fairly unpredictable. And the faster-spinning Earth and the unstable continent means that the Earth was highly volatile and there was no natural shelter for a human to hunker down in. Tectonic activity from the shifting plates was common, and a devastating earthquake could endanger a visiting human in a hurry. Unprepared and unequipped, a human’s life in this environment would be measured in minutes – because it wasn’t a world meant for us.

But that doesn’t mean it was totally unsurvivable. Visiting Earth a billion years ago, if possible, would be approached very much like a mission to another planet. This means highly specialized gear, designed to circumvent every single element of the environment. But in some ways, this would be much simpler than heading to Mars or Venus. For one thing, there’s one element of this world we’re used to – gravity. Gravity has existed since the planet was formed several billion years earlier, so visitors wouldn’t have to worry about unpredictable events knocking them off-course. Additionally, there is an atmosphere, and it isn’t actively toxic, so while a space-suit-like outfit with life support would be essential, a tiny flaw wouldn’t mean instant death. But the longer the visit, the more resources would be needed. Any visitor to this world would need a suit that could provide them with protection from the frozen atmosphere. It would need to be hooked up to a constant supply of oxygen, as there would only be a few minutes warning before it was too late should the supply be interrupted. That’s the immediate threat – but if this was a longer-term mission, other supplies would be needed. Namely, food and water. Neither are available on Earth during that time, so a good supply of fresh water and some simple packaged foods would go a long way towards extending the visit. The good news is, as long as the visitor is hooked up to oxygen, they could briefly take off their helmet to eat and drink safely outside the confines of their time ship. Now we just need one simple thing – a time machine!

But what would the purpose of this visit be? It would be a desolate world with only the building blocks of life, and no one would be excited to see it – except, of course, scientists! Evolutionary biologists would no doubt be thrilled to get a look at life on Earth in its earliest stages before the evolution of life took a quantum leap. At this point, life on Earth is cooking, and everyone knows that a lot of chemical changes happen in a hurry when you cook. The Proterozoic Eon may have seemed like a laid-back period on Earth, ending with another snowball Earth period that froze much of the world solid – but under the surface, it was anything but. Because in the next few hundred million years, a lot would change. The Proterozoic Eon would end approximately 538 million years ago, and animal evolution would begin a little before that – around 750 million years ago.