An intelligent race evolves on a planet with no moon or axial tilt, which is tidally locked to its star, and has a very hazy atmosphere.

So there are no seasons, no day/night cycle, and the stars are not visible either. The planet has a permanently dark and a permanently bright side, which will probably cause some nasty weather, but the important thing is: there is no natual phenomenon which would force the concept of time on its inhabitants, no periodic events which are always the same and affect everyone's life.

How will they organize their lives? How do they cooperate on tasks when there is no such thing as "tomorrow" or "at dawn"? How will a lack of seasonal agriculture or animal migration affect society?

Even more fundamental: can human-level intelligence even develop when there is no real need for planning ahead more than a meal or two? How different will their thinking processes be?

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    $\begingroup$ They might still invent something like an Hourglass. At start for the most profane reason: cooking something right to the spot. The invention of "hourglass" might spread into other parts of life too. E.g. "We'll meet when the Hourglass has emptied the third time!" $\endgroup$ Feb 22, 2017 at 11:14
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    $\begingroup$ Telling time when it's always day $\endgroup$
    – Separatrix
    Feb 22, 2017 at 11:20
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    $\begingroup$ Plants still will have something like lifecycle. Amount of time between a meal and feeling hungry again will be about constant. And so on. $\endgroup$
    – Mołot
    Feb 22, 2017 at 11:20
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    $\begingroup$ I'd separate this into two questions. "how can human-level intelligence even develop when there is no real need for planning ahead more than a meal or two" is really a completely separate question with its own set of assumptions. I'd argue that such a statement has never actually been true about a species (they at least have biological clocks preparing them for reproduction at some later time). I think it's better to focus on the first question you had, and make a new question for the one about development later, if needed. $\endgroup$
    – Cort Ammon
    Feb 22, 2017 at 15:18
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    $\begingroup$ Seems like a ridiculous stretch to assume that because there's no day/night cycle that you have no reason to plan more than a meal or two in advance. $\endgroup$ Feb 22, 2017 at 16:57

11 Answers 11


They could likely develop both time and technology, but likely very slowly

If we postulate that there would be essentially no variations in the nature around them - constant light, constant food supply, constant season - then timekeeping will be difficult, but not impossible.

Discovering time
Unless everyone is immortal, then one thing they would notice to be cyclic would be lives. They would eventually realize that everyone grow old and dies, which would give a base for starting to track time. This would still make it tricky as the time which is required for a life is quite long and it varies a lot from individual to individual, but they should still notice that something passes as they get old. A shorter measurement would be hair growth ("do you remember when we went on that trip, it was when your beard was only a hand long"), but that would be affected by their biology (maybe they don't have hair) and their cultural setting (maybe long hair is taboo). If nothing else, then they would still eventually notice that seeds planted eventually will grow; even if there are no vegetable cycles, they ought still have noticed that a tree which once were only the height of one man now stands five man tall.

Another thing they can learn about the passage of time indirectly would be from child's play. If they are playing with sand or water and pouring it from bucket to bucket, then they would eventually notice that it takes a bit of waiting for the pouring to complete. This would allow some smart individual to standardize that a sand pouring from a certain sized bucket to another would take a reasonable long waiting time. Lets call this reasonable waiting time "an hour". And by keeping track of how many pourings of "an hour" that one needs to wait, it would be noticeable that e.g., the hunting party usually takes five pourings of "an hour" before they come back home, but sometimes less and sometimes more depending on how easy the hunt was.

But would they ever develop any further use for this? That's hard to say - someone ought to be interested in measuring stuff, but it will take quite many pourings of "an hour" before the beard gets noticeable longer or before the tree grows to twice the size. And by the time one have poured enough hours for an entire life, then one have likely lost count several times over.

Conclusion on time: they would, at least indirectly, notice that there is a passage of something. Whether they will understand the concept of time from it and whether they will use it for something will highly depend on the wise elders of their society. It is not unlikely that they never will understand time, but it is highly possible for them to do so.

Developing an advanced civilization
As for the development of an advanced civilization - if they live in quite tropical climate with no dangers of lethal weather, no dangers of long periods of food shortage or anything else in nature which would force them to plan ahead, then why would they?

If one compare how advanced different civilizations have gotten, then there is a very strong correlation to how lethal the environment is. As example: the further up north people have lived, the more important it has been to collect food for the winter. If there always will be fruits on tress and animals to hunt, then why bother collecting for half a year in advanced?

This does not, however, mean that they cannot develop any advanced civilization. Both Mayans and Egyptians developed quite advanced civilizations without a real need to gather food for the winter. Nonetheless, is an undeniable fact that the more one is forced to plan ahead by nature, the more inclined individuals will be to figure out smart solution to make it in time for the nasty period and to survive it with little to no means.

Part of the development towards a more advanced civilization would likely be if they decide to start growing crops instead of being satisfied with a hunter/gathering society. By settling down, they would have more time to tinker and a higher need to develop solutions - one can plough a whole field manually with a shovel, but if one is smart enough then one will realize that it's less of an effort to do so if one creates a large shovel and strap it to an ox. One can drag heavy building materials entirely by hand, but it is far more convenient to use wheels (something which, interestingly enough, Mayans failed to invent despite an fairly advanced civilization).

Conclusion on development: It is likely that they would become quite lazy and not really develop any advanced technology unless nature forces them to, but there is nothing which prevents them in doing so if someone find it amusing to tinker with inventions. They would likely eventually reach a decent tech level, especially if they settle into small towns, but without a harsh whip from nature, it would likely take much, much more pourings of "an hour" before they would do so.

So, to assessing your questions

  • Can human-level intelligence even develop when there is no real need for planning ahead more than a meal or two?. Yes, high intelligence can develop despite no need to plan ahead. Humans only needed to plan ahead for a meal or two when the majority of our intelligence developed, but still we got really smart. There are several theories on how and why our intelligence developed, but it is believed that one of the major driving forces is the development of our language which we benefited from when hunting. Other animals also show remarkably high intelligence without the need to plan ahead at all. Take crows as example, they are capable of both using tools and advanced problem solving, and they might have a rudimentary language.

  • How different will their thinking processes be? This is impossible to say for certain without knowing more about their culture. If you mean compared to humans in general, then it can be either the same or completely different depending on what you as author want it to be. Cultural differences can cause completely different ways of reasoning - just look at how various cultures among humans might reason. If you want a baseline for how they might think, then I would point towards tropical cultures on earth - however, I am not skilled enough to give an fair overview on how they might differ from, e.g., an Eskimo's way of reasoning.

  • How will they organize their lives? How do they cooperate on tasks when there is no such thing as "tomorrow" or "at dawn"? Again, it depends on how you want to create their society. You can gather a lot of references from how housing and organization looks in warmer climates. My guess is that most of them would take the "day" as it comes, it will be hard to say when will be active at which point if they have no day cycle to organize sleep from (will they even have sleep?). Likely they will do stuff when the need arises. If they need to build a new house, then they will build a bit when everyone interested in it's completion have energy to do so. If they need to harvest grains, then they will probably do so when the grains are done.

  • How will a lack of seasonal agriculture or animal migration affect society? I point again to warmer climates. I saw a documentary about the life in an African country (can't remember which), where they had a fairly decent amount of crops around naturally. They spent their days with going out hunting if they felt like eating meat, they gathered grains fairly often as it was a base food, they built a new house for a newly formed family which took a couple of days. Whenever they didn't need to gather food or do something immediate, they largely spent their time socializing and strengthening their relationships.

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    $\begingroup$ One factor is that the tidally locked state would create rather extreme weather - that could make the environment quite lethal unrelated to the food supply. But a very thorough answer! $\endgroup$ Feb 22, 2017 at 19:20
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    $\begingroup$ Fun fact: Galileo used heartbeats to measure time. Under the assumption that the being of OP's world have a circulatory system, that could be discovered if there is interest in medicine. Using that method, Galileo found simple harmonic motion (pendulums), that would lead to clocks. - Also consider if the beings of OP's world are naturally social, they may sync their sleep and eating time, which may lead to a rudimentary notion of time that could be developed in less than a lifespan. Then again this world may have little pressure to evolve beings with such trait, but that's beyond the question. $\endgroup$
    – Theraot
    Feb 23, 2017 at 3:49
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    $\begingroup$ Re: "Both Mayans and Egyptians developed quite advanced civilizations without a real need to gather food for the winter." - The Egyptians didn't have 'winter' as such, no, but they did have a specific plant/grow/harvest cycle, based off the flooding of the Nile. And they still made plans (as I assume the Mayans did): you have to know how much food to store so you can send a good portion of your population off to fight, or even just to sell: Egypt was the breadbasket of the ancient world $\endgroup$ Feb 23, 2017 at 18:58
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    $\begingroup$ I myself disagree with the use of life–and–death cycles to measure time. They would learn of the concept of time, surely, but it probably wouldn't relate to the same linear concept that most of us take for granted. Those periods are too variable and too long: they would need to observe the lifespans of creatures who lived much briefer lives than their own. I suspect they would develop a conception of Time — not necessarily timekeepng — which resembles the Australian Aborigines: multi-layered and spatial. $\endgroup$ Feb 25, 2017 at 5:38
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    $\begingroup$ @can-ned_food Then you agree perfectly with my answer, that was the message I was trying to convey. $\endgroup$
    – Mrkvička
    Feb 25, 2017 at 8:16

They are intelligent, therefore they can notice that they grow up. Growing up is change, and change can only occur in a dimension called time.

You might ignore the concept of "meter" or "yard", but you can still understand that if two positions are different, they differ on something called "distance".

By analogy they can start to think about a temporal dimension they need to be able to quantify. The lack of periodic astronomic events will only affect their choice on the number, not on the concept of time. Before standardization each city had its own "metric system", the same could happen on this planet, with each city having its own "temporal system".

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    $\begingroup$ Agreed. And ironically their time system would probably be better as it wouldn't be based on local phenomena. $\endgroup$
    – James
    Feb 22, 2017 at 15:10
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    $\begingroup$ Indeed, I think the question asker is vastly overvaluing the importance of day/night cycle and season to developing a sense of time. $\endgroup$ Feb 22, 2017 at 17:00
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    $\begingroup$ And eventually someone figures out that quartz oscillates in a very regular manner... $\endgroup$
    – Joe Bloggs
    Feb 22, 2017 at 17:19
  • $\begingroup$ @Shufflepants I think the answerer and you are extremely much undervaluing the importance of such cycles for the development of a sense of time. It's a huge step from the basic observation that things change to measuring and structuring time. It just seems natural to us because we have never known a world without it. $\endgroup$ Feb 22, 2017 at 19:13
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    $\begingroup$ @MichaelBorgwardt Asynchronous computing systems tend to avoid relying on some structured notion of time, but they still have notions of ordered sequences, joins, forks, etc.. These people would probably be more like that; their notion of time would be more well-developed than our classical notions out of necessity. Sorta like how people in countries with multiple official languages learn more languages. $\endgroup$
    – Nat
    Feb 23, 2017 at 18:24

How will they organize their lives? How do they cooperate on tasks when there is no such thing as "tomorrow" or "at dawn"?

If the aliens need to periodically eat and drink, they could measure the time by getting thirsty/hungry. "Two big meals ago" or "before I get hungry again" are very approximate concepts, but might be enough for some cooperation. And, of course, they might have a pack leader who just says "me hungry, all go hunting".
If not - for example, the aliens just constantly photosynthesize, and the weather and predator attacks are unpredictable - they will simply cooperate when in trouble.

How will a lack of seasonal agriculture or animal migration affect society?

Far less than "being an alien culture". I mean, our current society is not that affected by seasonal agriculture or animal migration, too.

How different will their thinking processes be?

Can vary from "total aliens with no concept comprehensible by human mind" to "they think just like the Amondawa tribe".

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    $\begingroup$ Days, moons, and seasons can form the basis of universal time standards. If two people at the same longitude both agree to do something at noon in 57 days' time, and they can count, they will be able to perform the action nearly simultaneously without any need for further communication or synchronization. Concepts like "hunger time" would, by contrast, not allow for coordination without ongoing communication since one tribe might consume 27 means in the time it takes another to consume 25 or 29. $\endgroup$
    – supercat
    Feb 22, 2017 at 20:52

Are you sure there isn't none?

Animals and plants have specific cycles that are somewhat sync'ed together. Those cycles are important for those creatures - they control growth, pheromone release, estrus, and several other things. We're not even dealing with the need to sleep here - it's just the normal, less perceptible stuff.

A child takes some months to be born. Girls have their first red week a few years in life, around the same age. Children learn to walk and talk at certain points in life that are more or less the same, with some variation.

People eventually die.

People poop.

You can try to take away most of the differences in climate and whatever, but in the end you're still limited by the speed of the chemical reactions that make stuff happen. Those reactions aren't random - life is just a overly complex engine to process food and make more of itself. And, as every engine ever, every step happen is a predefined chain that ends up repeating itself again, and again, and again until you don't have anymore fuel. Even the sun works somewhat like that - the fusion cycle will going while it has fuel for it.

In your case, you climate will be your large-scale clock. While you may try to take away seasons and other stuff by removing the axial tilt, you still large-scale wind-streams, clouds, rain, and a lot of other stuff. The climate will change according to the distance from the sun that - unless you go with a perfectly orbit - will create some sort of seasons on your planet.

If you really want to go with "plants are random and there is no sync between them" (good luck explaining how flowering works on that case), a village just need a single tree to be able to track time.

When it flowers? When it gives fruit? How long does it take for a fruit to grow ripe?

You can't go with "random" for those.

That Said,

The simplest non-sun based clock I can think of is the water clock, which, really - your people won't take long to figure out how it works. It's that simple.

  • $\begingroup$ All life on their planet could be asexual. Flowering wouldn't matter. Fruit wouldn't matter. New plants would just 'show up' randomly. $\endgroup$ Feb 22, 2017 at 15:55
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    $\begingroup$ @MilesPrower The question didn't specify this, so I'm supposing a earth-like planet unless otherwise noted. If that's the case, I think the OP should be a bit more clear... $\endgroup$
    – Mermaker
    Feb 22, 2017 at 16:00
  • $\begingroup$ Point taken. I was not considering it being earthlike due to being tidally locked to it's star.. life would be unlikely to develop periodic behavior on such a world. $\endgroup$ Feb 22, 2017 at 16:11
  • $\begingroup$ @MilesPrower To be fair, a lot of the preconditions of this world seem excessively arbitrary and not well defined. It seems more like a thought experiment than a really Wordlbuid-esque excercise... $\endgroup$
    – Mermaker
    Feb 22, 2017 at 16:56

Assuming that they sleep, they would at some point probably find it useful to synchronize their sleep cycles so that they would could work on projects that are best accomplished with multiple helpers. Anything from hunting to lifting heavy objects.

From there, I could see that it might be useful to have basically two sets of sleep cycles: an A Team and a B Team, so work could be attempted/accomplished at any time. That would define a "day": a complete wake/sleep cycle for both A and B. Even before then, a complete (average) sleep cycle would define a unit of time.

Other activities could also define units of time.

How long to walk as far as you can see? That might be called a Long Walk.

How long can you hold your breath underwater? How long does it take you to eat? How long does it take for meat over a fire to cook? How long before milk spoils and is dangerous to drink? How long does it take for wet clothes to dry?

I don't think it would be that abstract.

  • $\begingroup$ +1 There are plenty of things in life that are inextricably linked to short periods of time (and work/energy), which would lead to standardisation without the long periods of seasons, etc. Sure, they might not think in seconds, but it will certainly be shorter than days or seasons. $\endgroup$
    – adelphus
    Feb 22, 2017 at 22:56

Even at the dawn of civilization, there is always something that can show that time passes. Sometimes long, like the time it takes for a new baby to grow into an adult, or for an insect-like or snake-like creature to molt; sometimes short (in the grand scheme of things), like a long walk between caves, or "I just ate and am not hungry" to "I'm hungry now"; and sometimes very short, like the time it takes for a wave to hit the beach and retreat, or the time it takes for a pebble to fall to the ground, or simply saying a word or phrase (one hippo-analogue, two hippo-analogue...).

That can give very coarse time values, or very short time values; you wouldn't be able to cook a roast by pebble-falls (start the roast, drop a pebble five thousand times, check if it's done), nor would you be able to use lifetimes. A long walk (five times around the cave system) may work, however.

As time goes on and technology improves beyond the stone-age, people will see that sand or water takes some time to fall, and can make hour-glasses or water-clocks. Candles take time to burn, so a well-marked candle could easily (and fairly regularly) show the progression of hours. Even a lamp burning fat could have markings on the side to denote time: fill the lamp and light it, put the roast in once the fat has melted, take the roast out when the fat level drops four lines. Once time can be marked, inventions measuring (and using) time will spring up quickly. Knowing that Junior takes half a candle to walk to his friend's hut to borrow a cup of sugar, Mom won't believe junior when he makes an excuse for taking a full two candles to go and return. And farmers can plant on a schedule, once every full water-clock-cycle, to make sure food ripens evenly, and not all at once.

Once time can be measured at all - and this will happen early on - your people will soon find ways of measuring time more and more accurately, and will eventually think digital watches are a pretty neat idea.


there is no natural phenomenon which would force the concept of time on its inhabitants, no periodic events which are always the same and affect everyone's life

So you say they have some kind of plant. So the plant have vegetation stages. BAM! Periodic event.

You say they have tasks. BAM! Fulfilling a task take... time.

Lack of season agriculture is nothing hard. Look at tropical regions. For example on Cuba you don't have "winter/summer". You have "hurricane season".

You didn't explained why you think there would be no need to planning ahead.

  • $\begingroup$ Plant vegetation stages would start at different times for different plants even of the same species because there is nothing for the plants to synchronize to. Not very noticeable. Doing a taks takes time, but how long? You have nothing to communicate the length. And hurricane season is caused by changes in water temperature, which are caused by axial tilt, which my world does not have. So there cannot be weather seasons. On Earth, seasonal changes in food supply make planning ahead crucial for survival, on my world this evolutionary pressure would be missing. $\endgroup$ Feb 22, 2017 at 12:06
  • $\begingroup$ Single plant would have vegetation cycle which would be sufficient to notice changes. From that you would have one time period "the vege" something shorter could be "going from one side of crop to another with 50 veges in line of said field". Hurricane was just and example of naming and having a different season. Seasons could also be present by the fact that planet can be in different distance from it's star. $\endgroup$ Feb 22, 2017 at 12:18
  • $\begingroup$ @MichaelBorgwardt - plant vegetation times will be different for different plants, but that just makes more time markers, not fewer. Maple sugaring season is several weeks before birch's, so now I can place weeks for several months with a lot more precision (before this, after that, during the gap, during the overlap). Or comparing how long it takes a dandelion to flower versus a cherry blossom, or how long from flower to seed of a single plant, or from sprout to flowering age - and any given plant species should flower at about the same time because they reproduce with each other. $\endgroup$
    – Megha
    Apr 6, 2017 at 1:38

I first consider units of measure. Any highly-intelligent beings will be at least somewhat interested in measuring things that change over time. This would require some established unit of measurement if any mathematical precision is to be achieved. Without their own moon or any visible heavenly bodies, intelligent cultures would find other ways of establishing units of time. For example, they could come up with a "podt", the time it takes for a pebble to drop to the ground from roughly a "zodt" high, and using their numbering system (possibly base 7 because they have 4 fingers on one hand and 3 on the other, or they are smart enough to pay that much respect to prime numbers), they could extend that to larger collections of "podit" (plural) much as we do with our metric system.

Perhaps the lack of significant natural time-telling mechanisms, such a culture would develop with a different take on the meaning of time and how it influences the world around them. In the case of humans, we see time as happening on a line, but that isn't necessarily the case. Perhaps their unique perspective would give them an unexpected advantage when it comes to understanding time.


If these people were sensitive to these things, they might be able to detect the incidence of cosmic rays. Although the rate of collisions would vary with activity of their local star or stars, these would be a way to measure time between each collision between a gamma photon and their sensory apparatus. A Geiger counter, for example, reports radioactivity as an audible ‘click’ each time a charged particle or gamma photon ionizes the gas inside a tube, causing a small difference in voltage within the tube: https://en.wikipedia.org/wiki/Geiger_counter

Possibly their bodies are synchronized to the rate of these radioactive events much like an ectotherm with the ambient temperature: more cosmic rays speeds their metabolism.
Don't forget the nuclear decay of abundant radio-isotopes, also.

So, although you stipulate that there are “no natural [phenomena] which would force the concept of time on its inhabitants,” I recommend that you thoroughly reconsider the nature of that world in which they would live — both from their perspective and from a theoretical one.

  • $\begingroup$ I was thinking along the lines of atomic decay as well, you beat me to it. Initially, they will notice part of the less glamorous life/death cycle is the decay rate. Curious minds will want to know how and why decay occurs, and as scientific understanding reaches sub-atomic understanding, they will develop clocks measuring time based on the rate of atomic decay of their most studied radioactive element, or alternatively measure the constant frequency of electron energy state changes like we do with atomic clocks. $\endgroup$
    – N2ition
    Feb 24, 2017 at 20:01

Even in such environment plenty of evidence of the passage of time will exist

I imagine that a earth like planet orbiting tidally locked to a red dwarf star will have stable and strong winds and rivers. Since the pressure systems will remain constant I expect the atmosphere and oceans to have very stable flows like the oceanic currents that we have on earth, maybe way stronger.

With stable pressure systems, topografy will generate turbulence, some weather patterns will be cyclic. In some places the wind changes may happen periodically. Stare to a turbulent river for a few hours and you will understand what I mean.

With stable winds, dead trees may wave like a pendulum and may be the basis of a local time measurements. Not very easy to avoid cyclic patterns on nature.

But let suppose we can make an environment free of the clues about time

I understood you question to be about the human learning. Not about the exact environment.

For the sake of the argument, let say we could produce such a stable environment and that does not make the planet uninhabitable. Even without any clues of the environment, people will develop history based on the life interactions. That will give the understanding of sequences of events which is what I understand as time.


Time will be measured by wave travel over distance.

As they notice the time delay between the source of a sound emitted and its arrival at a distance away, they will use this as a way to measure both time and distance, depending on which one is known.

When they know the distance between points, they can set up their pendulum clocks to a set interval to meet the time it takes for a standardized very loud noise to reach a certain distance away. A set of high quality pendulum clocks can be calibrated to the one standardized location set up for this purpose to eliminate sound barrier interferences that could occur at other locations, and other clocks would then be calibrated to these. A periodic recalibration would be set up using whatever calendar they develop based on other natural rhythms they notice (as other answers indicate, there are many).

Regarding your question specifically as to whether humqn intelligence will advance, it is within human genetics to become more intelligently advanced through learning and adapting to an environment, no matter what that environment is. To learn is intrinisic nature of humans, therefore although the rate of intelligence growth will change based on the environment, any variety at all in the environment will activate learning and increased intelligence.


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