What could cause humanity to migrate from land to water?

Question

I'm constructing a world where the humanity had to migrate from land to water somewhere in antiquity. In this world, humans are living on seas and rivers. They live both on pier-like and other fixed platforms near the coast as well as on rafts strung together into larger settlements offshore. Fishing and sea-plant farming (algae etc.) are the main sources of food. Ships and boats are pretty much the only means of transportation.

The land still exists (topography is the same as of the real world) - no "Water World" scenario. However, humans only visit it for brief periods (several hours, maybe up to half a day) and only to hunt/gather/acquire wood and other land-only resources. There are no permanent human settlements on land. Obviously, this makes certain activites tricky (land farming, mining, heavy industry) but the technical consequences will be deal with in a separate question.

Other life on land exists more or less unchanged (some modifications are allowed to enable a viable answer but I don't want a mass extinction of land-based life).

My question is: What event (can be sudden or gradual) could cause such a migration happen?

One caveat is that the event must be global (or eventually global) so that humans all over the world are affected and move their lives to water independently and without communication.

Several thoughts of my own (ideas and associated problems):

• Predators: Humans in real world are apex predators primarily due to the highly developed intelligence and social structure. If a smarter and more dangerous predator has evolved on land, why hasn't it taken to the sea to pursue its prey?
• Superstitions: No actual monsters on land but tales of such passed from generations are preventing people from returning. If so, how did these originate in the first place? And, given human nature, what would prevent people to go against the "wisdom of the fathers", settle on land and eventually bust the myth?

Answer 1

1. Irregular geological / tectonic plate activity - Perhaps at some point mantle became unstable resulting in frequent earthquakes. These earthquakes were small scale but unnaturally damaging to the human settlements. Imagine deep fissures opening up randomly in the heart of cities, small lava eruptions that open and close without a warning, EM flares coming from ground frying electronics, disrupting human brain/hearts and what not. But all large water bodies are completely free of it because water absorbs it all so humans gradually moved to seas/rivers. As for animals, they suffered from losses as well but eventually adjusted and thrived with humans gone. This satisfies your requirements of people living on water and not going inland for very long durations.

2. Post-apocalyptic world - Let's say human population keeps increasing eventually to the point that water bodies become viable real estate. It becomes commonplace for people to live on boats and large cruise boats type of structures are common as apartment complexes. Now, cause an apocalypse on land that makes the water settlements far safer than land. Perhaps it was a super-bacteria/virus that thrives in concrete/asphalt but not on lighter plastics/woods used to create the houses on water. So, humans didn't "migrate" to water, they were already living there and then something happened on land that resulted in only the water settlements surviving.

3. Zombies - Zombies can't swim. Humanity can't beat the zombies and must start living offshore.

4. Predators - Let's imagine the movie "Jurassic world" as what its name suggested instead of being a working Jurassic park. Dinos have either fully integrated in the society (Dino pets, Dino powered lawnmovers, Dino egg benedicts) or thriving in relative secret in jungles and something causes them to become the apex predators (human partial extinction due to plagues, wars etc). Sounds outlandish but dinosaurs can be enhanced or replaced with anything else as long as it can't survive in water and doesn't exterminate all other flora and fauna. It could even be as simple as triffids or Alzheimer's like symptoms inducing plant/microbes.

5. The last ship - In this scenario, an apocalypse has happened and only the ships out very far away in the oceans have survived. The land is not livable except by plants and small animals, so they restart the human civilization on water.

Answer 2

Land is barren while the seas are bountiful

Desertification spreads across the lands while the seas remain untouched by the scourge of the Gods. Those who make it to the shores are pushed out to the seas to find a new life. The many fish and other animals of the ocean provide for a hearty diet, if a bit difficult to catch, as people have to give up their hairs to create nets.

As time goes on the wooden boats of old begin to decay, and in a twist of luck and fate, a small fleet comes across a decaying sea predator corpse on a nearby shoreline. Before then, such predators were the stuff of nightmares, as each kill only attracted more to the slaughter. But the waters were calm that day so the fleet came ashore to examine the corpse. They discovered that the bones are both light and strong, perfect for creating new ships. The sinewy muscles can be spun into a powerful fiber that defies decay as long as it remains away from the air, and the fat can be boiled into a paste that holds everything together. In addition, they find that glands in the brain produce a powerful odor that turns other predators of that type docile, making them easier to kill.

After that fateful day, the small group of survivors use their newfound discoveries to create an impressive fleet, and within a generation they go from being desperate survivors to hardy conquerors.

(This deals more with the sister question but it was difficult to do one without the other and decide where it belonged best.)

Answer 3

Disease

It's going to be the wealthy and the already mobile who lead the way. They're going to try to stay safe in sealed enclaves but once a plague goes global the only way to truly quarantine yourself in a controlled environment will be to go to sea.

A disease carried by just about any mammal but mostly only affecting humans would drive people off the land to stay safe. Only the suicidally brave or immune would risk going back to land to gather resources.

Answer 4

There was an AI war with a very interesting quirk

Picture that roughly 50-100 years before your scenario, mankind was at it's peak. We had vast sprawling cities, booming industry, and we were just beginning to rely on intelligent machines for everything; civilian, industrial, and unfortunately for us, even Military. Machines were everywhere, there was roughly one Mechanized intelligence for every 2 humans on the planet.

One of the major powers aimed to capitalize on this and started development on a sort of "mega-weapon" super virus with the goal of converting all the AI of a rival power to their control. However, they never got the chance to use it, as a group of radical Eco-terrorists managed to get a hold of the virus and then hastily modified it to use for their own agenda. The result of this patchwork modification:

All Intelligent Machines are compelled to protect the land from mankind

The eco-terrorists released this virus and it spread like wildfire among the worlds machines. We lost the ensuing war, and modern civilization collapsed. During the conflict however, Mankind noticed their one sanctum was the water. The machines one-track minds and extremely literal adherence to their programming meant that they did not initiate aggression towards humans that were quite literally "not on the land".

Mankind had no choice but to start rebuilding society off shore. At first there were countless efforts to try to re-settle the land, but any time the machines found out the location of a new settlement, they would attack like antibodies to remove the human infection. After enough failures and enough lost lives, mankind finally learned it's lesson and stopped trying.

Decades later, the land is still seen as a very dangerous and taboo place to man. Nature has done quick work to reclaim much of what man has built. The machines still silently patrol the vast wilds of the old cities, and they might even be one day viewed as gods as the knowledge of the past is gradually lost. Soon, only the bravest of hunters will venture into the monumental ruins of man to look for supplies and food, most do not return.

Answer 5

Two other options which haven’t been mentioned yet:

No clouds

Due to some particles in the air (maybe a biological weapon?) rain happens almost instantly as soon as water evaporates. The only remaining sources of water are large lakes or oceans. This would also mean that all land turns into deserts except close to the water.

Radiation protection (only makes sense if they also live underwater)

Water is a pretty good shield against UV radiation and gamma rays. Maybe the sun went haywire and is regularly emitting huge bursts of radiation. The only surviving life forms would be in water and living under water would be a good way to protect against it.

Answer 6

Termites

Consider the question: If the insects declared war, who would win?

If all termites in the world would cooperate to get rid of humans, they quickly might. Except that termites can't swim. We can't kill all insects, but with large anchored rafts, humans are quickly forced to learn growing sea vegetables as fish alone is not good enough.

Answer 7

An intelligent predator living in groups (perhaps Neandertals? Large dogs? Monkeys? Bears?) that got an advantage over humans requiring them to fortify themselves in such places.

Switzerlands lakes have many human communities that lived as you described (as protection from other humans). Aztecs at least partially become supreme in their area because they were difficult to attack although vastly outnumbered when they first started.

I would think humans would have fought for the land and lost, so now remnants have moved onto water where they can survive, eventually developed technology that gave them a clear advantage in that arena, going onto land only in defensive groups prepared for fight-or-flight. Then attrition keeps their numbers down. Those groups who retreated to mountains and forests were all overrun over time etc,. Except for one group with an exceptionally well endowed and scantily clad chiefs daughter (considering how cold the mountain is) who the protaganist eventually hooks up with.

Answer 8

Allergies

Through some mutation, we all developed severe allergies to pollen and various plant life. Heck, some people are allergic to grass; maybe we all got that allergy too. You might say this wouldn't stop people from living on rocks, but we wouldn't be able to (easily) farm plants or animals. The easy way out is to move to the water.

This gives you a nice excuse to keep people away from land and can explain why people can only visit it for a short time: maybe only the people who have less severe allergies can venture out, and only in protective clothing and face masks. Plus you don't have to change the current landscape, since it's strictly a human change.

Second thoughts: I suppose this wouldn't stop people from living in places like the desert or the tundra, so this would only really work if you make the allergies cover nearly all plant life and perhaps most mammals (like dander allergies). This way, it would be more difficult to hunt animals in "hospitable" environments than it would be to just move to the water and fish. People who live in arid regions still rely on agriculture, so if everyone is allergic to plants, they'd be living in the desert and yet still need stuff imported from the sea. There could be a pressure for people in these environments to move closer and closer to the sea to make trading easier until eventually, they just live on the water. There's nothing for them on the land.

Answer 9

I'm hard pressed to find a reason why humans would abandon land completely especially if they are as ingenuous as humans are in the real world. Depending on how technologically advanced your humans are, I imagine that they could figure out a way to deal with predators with lower intelligence than us--just like we have for every real world predator. Similarly disease, radiation, solar activity, and tectonic activity offered by other answers would still affect humans living on the water.

An intelligent predator that cannot swim/create naval craft. This might include zombies, but you're gonna have to think long and hard about what it is that discourages these creatures from coming into the water.

Global climate change. This I think is the most realistic option. Perhaps the only arable land is on the banks of water on your world, and this is where the humans get their supplies.

Scorched Earth. This is farfetched, but maybe a comet or series of asteroids happened to hit land all over the Earth, resulting in the elimination of most life, removal of arable soil down to bedrock and perhaps causing shock-metamorphism in much of the land. Now people could live on land, but there would be no reason for them to if they couldn't farm or hunt--so they may as well live on the water or along the coast where they can farm fish.

Answer 10

We can break the options down into two categories; depending on the general feel of your world, a mixture of answers in both categories could be suitable. So, those categories are Land push and Water pull.

Land push - Humans are being pushed away from the land

This is well covered by the other answers here, however, as the land is largely the same then we'll likely need purely human social constructs to keep people out. Humans are largely only afraid of other humans so an additional option could be societies in which only the Elite are allowed to live on the land. Lots of very dark routes there - maybe peasants are hunted as some kind of awkward sport. Nice.

Water Pull - Humans are being attracted to water

This hasn't been mentioned so far; Focusing on this positive category completely changes the feel of your world. Essentially, what's making water so attractive? A classical example is that it has healing powers; maybe humans used such powers so often that they've become entirely reliant on them - it's something that could grow over time too.

Similarly there could be social constructs here - people simply don't know how to do anything other than fish; maybe literacy is limited (or simply doesn't exist) so sharing skills and techniques is a verbal only process. Trade doesn't work too well though. Other helpers on this more general category are asking yourself questions such as "what would make me move to the coast today?". Then consider how that can be amplified.

Answer 11

Dolphin and whale skin needs to stay wet, or it cracks. Our skin has to stay pretty dry, or there are infection issues (trench foot). Something that changed human skin to whale skin would pull towards water.

Something that made that valuable would explain why it wasn't cured. Some complex seaborne microorganism?

This is kind of sexier than I anticipated. Which never hurt a story, IMHO.

Answer 12

For a migration in the pre-historic times:

1. The easiest source of food is available from a ship, but not from the shore
2. Some sea animals that can be easily domesticated, and are really good at sea-land warfare (giant turtles?)

If the seas provide easy food and "livestock", instead of pre-historic shift from hunting to farming, there'd be a shift from hunting to sailing. The sailors would occupy the highest society ranks, inventors would work on improving the ships, the sea food would become the main food source.

After a while, the ships would get big enough for raiding the land settlements - they can attack with the warturtles, or "besiege" the land-dwellers, destroying their ships and cutting them from the sea food. Eventually, the land settlements would be colonized by the tribes of sailors.

As the sailing tribes acquire way more resources than the land colonies, they invest more in the technology development. Eventually, they reach the point where they don't need land colonies to survive. The land-dwellers either join the sea-dweller civilization, or are constantly looted by the bypassing ships and eventually destroyed.

Answer 13

This is documented in the history film Tremors and its many prequels, sequels, and spinoffs.

On a more or less serious note I cannot think of anything that would force us to stay on the water with only short land expeditions especially considering one option is to live on docks which means land based predators could easily walk out on docks along with insects. This would also mean we can be reasonably close to shore and so land based poison or radiation would not be a factor either.

There is of course unnatural phenomena such as the land is cursed and will kill you if you are on it for 24 hours but I do not think this is what the OP is asking about.

natural disasters wouldn't be the reason since it is much more dangerous to be next to shore on a dock with an earthquake which can kick up a title wave especially when it is a <h1> title wave. Lightning would be no good same with tornadoes and hurricanes.

Answer 14

Sort of a cross between Trilarion's "Poissonous [sic] insects" and limitlessinfinity's "Allergies" is the idea of a

Toxic Plant or Fungus

or a toxic microscopic symbiote (think mites) that is ubiquitous and which reacts over time with humans when they encounter it. I'm thinking of a world strangled with some kind of poison ivy, for example, to which naked apes with their exposed skin are susceptible, but animals with fur are not. Or a fungus like athlete's foot that will grow on people's skin from ubiquitous spores within hours, except that contact with saline water kills it.

That need for salinity in the latter proposal would slightly change your original vision, because people couldn't live inland up major rivers, but only in coastal bays and marshes, where the salt penetrates landward, or in the rare pockets like Salt Lake and the Dead Sea, where inland seas dried up and lost contact with the land. Maintaining contact with / rediscovering human tribes that had been nearly or completely isolated when their salt water bodies separated from the global seas would give you some fun plot points, too.

Answer 15

A mutation in the inner ear (related to balance) that when extended periods of time are spent on 'solid land' it leads to nightmares, headaches, and generally unpleasant unhealthy situations.

They found that spending a fair bit of time on a floating structure was enough correct the imbalance. Scientific research has shown that there is a difficult dance that can be done to counteract the problem, but it is rather impractical as it would take several hours of effort. The simpler solution was to live on the water and go about the daily tasks.

Further thoughts: It might not need to be debilitating, but just something uncomfortable. People could live on land, but their overall health and well being are improved living on floating structures. Or perhaps it wasn't initially so bad and over generations it has gotten worse and now if you spend a few days on land you develop "land madness". There is a lot of wiggle room to fit your need.

Answer 16

Unfortunate climate

Land mostly consists of desert, mountains, ice or swamps

Poissonous insects

Is not really a predator but may threaten your offspring unless you go somewhere where you can keep the insect population under control (on the water surface).

Huge weather irregularities (thunderstorms)

You need to escape them constantly and for example going once around the earth you can only do on the water. Maybe you even have to dive with your plattform when a storm comes.

Answer 17

Maybe aliens will visit earth and will teach how humans can be genetically modified so that humans can breath underground and never visit us again.

And this thing becomes a cool thing and everybody wants to live underwater and gets genetically modified.

After few years this genetic modification would affect them creating disease like asthma if they breath through air making difficult to breathe in air.

And it would be comfortable to live in water.

Answer 18

Worms

Well that or any other form of burrowing creature, a subterranean hunter which can't swim and can't stay above land for long but is lethal when it surfaces.

Trips to the land would require constant vigilance for wormsign/molehills etc

Answer 19

Luke Briggs sort of made the point I wanted to, however I'd include the recent bout of political uproar as inspiration. As mentioned, humans are their own worst enemy, and so I believe wide-spread panic, fear, and propaganda could also be a reason that drive people to live near open waters, then over time almost exclusively turning to water-based abodes. Considering politicians and people with vested interests will lie their way to obtaining their goal, this doesn't even seem like too far a stretch. I'd suggest that this sort of huge, socio-economical change would likely not fit well with a majority of people, but perhaps smaller groups of people would leave the skeptics, then stronger efforts to spread the propaganda may result in larger quantities of the population to move to the shore.

Considering how humanity is moving forward, some analysts mention a population crunch could begin wiping large amounts of people from the Earth, and so a mass-event like this could instil enough fear and confusion that they will likely listen for their leaders instruction. This situation could also be a false-flag operation-- the government (or even a secret global community) could conduct a mass-execution situation, then using the fear found from such an event, suggest people move to live on or near the sea.

As far as avoiding fantasy-type elements, like aliens and robots, I feel as though this is a possible solution that won't turn readers away, unless they're not a fan (or have experienced overkill) of recent politics.

Answer 20

Spore-Like Virus, but thrives in the absence of water. Limited exposure could be allowed, but if the ground is covered with this stuff, stepping on them causes them to become activated and airborne. Since the air has some moisture, the virus isn't able to travel too far, making large bodies of water a natural safe-zone.

Various animals can survive due to being able to frequently go in and out of water or just lick themselves. Living high up in trees could benefit as well. Salamanders or any animals with mucus covered skins could thrive. Could just be dangerous to mammals.

Some form of decontamination may be necessary, but that would just be a quick dip in the water.

Answer 21

Genetic Warfare

You could be living in a period post a serious genetic war.

1. Genetically modified resources. A nation, or multiple, could have figured out how to genetically modify a widespread resource to be harmful to humans. Several nations could have even targetted specifically each others primary races and thereby forced each other off the resource plentiful land where we humans have built basically all of our developments.

2. Genetically modified humans. People, whether they be nations or malicious individuals could have been targeting the water supply for dozens of years causing genetic defects in the next generation, such as severe allergies to certain wide-spread flora, like grass, or an insect like flies, or perhaps numerous things, or perhaps even more likely, we never figured out what exactly we're allergic to. This would mean that parent's would take to the seas to save their children from their severe allergies and would allow a period of time where adults could be land based, and any setup required (such as lots more boats, supply depots, or some other features your people depend upon) could be created.

Answer 22

A tyrannical regime which spans the entire world. It is headed by the descendants of the world's most notorious pirates.

They hate landlubbers. Being a landlubber is punishable by death so people are all forced to live on the high seas.

People can still get amazing things on land but there are loads of drones which hunt down and kill them.

All permanent settlements and infrastructure had been bombed out when the pirates took control because they are necessities for landlubbers used to modern comforts.

2% royalties please.