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Adapting to a World with Long Day/ Night Cycles

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Bend-It-Like-Zuko from Caldera, Fire Nation Since: Jan, 2017 Relationship Status: Showing feelings of an almost human nature
#1: Feb 25th 2018 at 11:34:52 AM

My current idea for a fantasy novel takes place on a planet whose rotational cycle is long enough that their days are in scale with our years. That is, the people count their age by how many suns they have lived through and dawn, daylight, dusk, and night have the importance of our four seasons. This isn't exact, but imagine 3 months of Sun, three months of darkness, with the twilight seasons in between. I was inspired by earth 's polar zones and wanted to extend the idea of midnight Sun/ polar night into more temperate climates.

I have already looked into the geological effects of extended light/ darkness and that isn't what I want this thread to focus on. I have large oceans surrounding the landmasses which helps alleviate the temperature gradient between the daylight and night "seasons" while the strong wind conditions caused are a story element. What I want help with is this;

How could plants and animals adapt to 3 months of darkness? Especially plants as they are so solar dependent in our world and everything else in the ecosystem is dependent on them.

How is human culture affected? What decides sleep when night is months away? How do they measure time? (if their days are on scale with our years, then what do they divide it into on a more short term scale like our years being 365 of our days?)

Like I said, this is a fantasy story and there is magic so story is more important than strict realism, but I want interesting ecosystems and cultures and I figured I should start by extrapolating on what I already have before just going by rule of cool.

KnightofLsama Since: Sep, 2010
#2: Feb 25th 2018 at 2:12:48 PM

[up] Animals would hibernate, plants would treat night like winter. For deciduous types, they'd shed their leaves and go dormant in the late evening and start budding around sunrise.

SeptimusHeap from Switzerland (Edited uphill both ways) Relationship Status: Mu
#3: Feb 25th 2018 at 2:27:55 PM

There would be no sleep in such a setting. Without a 24h cycle there is no selection pressure for cyclicity, and whatever biological benefits it has are highly unlikely to scale to one year long sleep.

The exact climate of such a setting would matter.

"For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled." - Richard Feynman
DeMarquis (4 Score & 7 Years Ago)
#4: Feb 27th 2018 at 3:04:00 PM

A 24 hour cycle is highly unlikly, but sleep serves an important rejuvination function in most animals, so some sort of functional equivalent would surely evolve in its place. If your lifeforms have brain hemispheres, unihemispheric sleep might become common. At least on Earth, hibernation does not entirely replace the need for sleep.

edited 27th Feb '18 3:09:09 PM by DeMarquis

I'm done trying to sound smart. "Clear" is the new smart.
MajorTom Since: Dec, 2009
#5: Feb 27th 2018 at 5:05:04 PM

Are we sure stuff wouldn't simply adapt/evolve a Circadian Rhythm that corresponds to the "days"? For example, humans who would sleep or be awake for months at a time by our measure but only a few "hours" by theirs.

Robrecht Your friendly neighbourhood Regent from The Netherlands Since: Jan, 2001 Relationship Status: They can't hide forever. We've got satellites.
Your friendly neighbourhood Regent
#6: Feb 27th 2018 at 6:45:42 PM

[up] That's definitely possible for certain organisms (as mentioned,deciduous trees on earth already follow this rhythm due to winter), but I don't see it working for animals. Physics does, after all, set the limits of biology and while hibernating for three months would be entirely possible, staying awake for the the entire following nine months (or, heck, staying awake for even as little as three months) would not be. Just simply because without the extended rest period that sleep provides, there's far too much wear and tear on the body and not nearly enough repairs going on.

The only animals on earth that can go without (some form of) sleep for more than three months are various invertebrate species who actually don't sleep their entire lives... But let's just say that they do not ever reach the milestone of being awake for nine solid months either. And even they need occasional periods of recuperative rest (they just don't sleep while resting).

At any rate, sophonts on such a planet might be seasonal nomads, travelling their continent (or at least their territory) once or even twice per 'day' to extend their use of whichever time of 'day' best suits them and minimize the amount of time they spend in times of 'day' that least suit them. If they're not nocturnal, fire might let them explore the night the way that it allowed humans on earth to brave the colder winters of the north. If their planet is tilted the way Earth is, they will eventually build their most permanent, most prolific cities and nations in the regions where the time of day is permanently the one that is best for them.

Angry gets shit done.
SeptimusHeap from Switzerland (Edited uphill both ways) Relationship Status: Mu
#7: Feb 28th 2018 at 12:46:08 AM

@Major Tom: Reserving judgment on that question. There is firm proof that sleep - whether unihemispheric or not - is essential for (higher) life seeing as we don't know any no-sleep mutants that would be viable. However that is not evidence that sleep would evolve in a place without a day-night cycle seeing as all life we know that sleeps developed in an environment with a 24 hours day night cycle, and "Cells started to synchronize their behaviour after a light driven clock, a bunch of maintenance work got attuned to the phases of this clock and thus eventually sleep arose and could no longer evolve away as too many functions got dependent on it" is a legit explanation.

edited 1st Mar '18 2:20:38 AM by SeptimusHeap

"For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled." - Richard Feynman
Fighteer Lost in Space from The Time Vortex (Time Abyss) Relationship Status: TV Tropes ruined my love life
Lost in Space
#8: Mar 5th 2018 at 6:36:30 AM

I find it to be a bit fallacious to say that, since we only have examples of higher life that requires sleep cycles, all higher life must require sleep cycles. All you need is a single counterexample to demolish the argument.

Life on a planet such as this, were it possible at all, would probably evolve a biological cycle involving high levels of activity during the "twilight" periods followed by sheltered hibernation during the bright and dark periods. There would be no external stimuli to base a diurnal clock on, so there would be no reason to evolve one.

Now, I said in the other topic that, from the standpoint of physics, an alignment of this sort would probably be unstable, and would shift over time as the planet approached being tidally locked to its parent star. Indeed, mathematically speaking, any body becoming tidally locked would have to go through a brief period where the day slowed down to match the year before stopping altogether. How long that would take would depend on a number of factors, including orbital radius, the distribution of mass on the planet, surface oceans, and things like that.

The main issue is that it probably wouldn't last long enough for large-scale evolution to adapt to it — the kind that takes place over tens of millions of years. Climatic conditions would be changing rapidly on a geological scale, forcing very rapid adaptation due to the environmental selection pressure. You'd find species in all states of this scale: some barely clinging to the margins and some newly thriving.

Any sapient species would have to adapt as well, but if it had significant technology, it would have plenty of time to do so. Changes wouldn't be macroscopically observable on a scale of living memory — anyone alive today would have only experienced today's conditions, going back many generations. Weird cultural phenomena could develop, such as "day deniers" — people who claim that their ancestral records of a time when the sun moved faster across the sky are fakery. Correspondingly, you'd have people denying that one "day" the sun will stop moving entirely.

edited 5th Mar '18 6:41:00 AM by Fighteer

"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"
SeptimusHeap from Switzerland (Edited uphill both ways) Relationship Status: Mu
#9: Mar 5th 2018 at 6:40:32 AM

That was unclear wording on my part. As-is, higher life always has a sleep cycle given the arguments presented. That does not mean that life evolving on a different planet would have such a cycle.

"For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled." - Richard Feynman
MajorTom Since: Dec, 2009
#10: Mar 5th 2018 at 8:01:39 PM

^^ Well physics wise you can have a non-tidally locked planet and still have "days" that can be measured in significant timeframes (less than an orbit or more than one). Mercury for example was once thought tidally locked, but it is not and will not become tidally locked until shortly before the red giant the Sun becomes envelops the planet entirely and destroys it. It has a 3:2 resonance, 3 "days" per 2 orbits.

On Earth at the poles exactly, the Sun rises and sets once per year. (Sunrise/sunset are the equinoxes.) A perfect 1:1 resonance.

Day length is mostly a function of rotation speed like Mercury but sometimes axial tilt like on Earth plays a part. If hypothetically a planet simply rotated on its own axis slow enough but was too distant to be tidally locked note , you could have "days" that measure in "years" or longer.

Or perhaps the planet in question is tidally locked to a non-solar body. It's a moon instead. Our Moon has a "year" of around 29 days. Each "year" on the Moon, one full orbit is also one "day", the Sun rises on a part of the Moon and doesn't set for about 14 days or so only to rise again on the 29th day. Such a setup could avoid the burning desert Sun-side hemisphere and the frozen ice sheet of the night-side with but the thin band of transition between the two of true tidally locked planets.

Fighteer Lost in Space from The Time Vortex (Time Abyss) Relationship Status: TV Tropes ruined my love life
Lost in Space
#11: Mar 5th 2018 at 8:05:39 PM

Those are all interesting possibilities, but you still have the problem of the planet's magnetic field to deal with, in that it wouldn't have a very strong one with such a long rotational period. If we're playing loose with our science, we can hand wave it away, but it would definitely be an issue for a real planet with that sort of rotation. Without a magnetic field, its atmosphere would be stripped off by solar wind over a long time period, leaving its surface naked to radiation and its life forms without much to breathe.

edited 5th Mar '18 8:05:47 PM by Fighteer

"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"
MajorTom Since: Dec, 2009
#12: Mar 5th 2018 at 8:12:48 PM

Planetary magnetic fields are caused by dynamo effects of molten/solid iron and what not inside. You could stop Earth on its axis right now and the dynamo effect internally would keep going like clockwork, it's irrelevant to axial rotation.

Fighteer Lost in Space from The Time Vortex (Time Abyss) Relationship Status: TV Tropes ruined my love life
Lost in Space
#13: Mar 5th 2018 at 8:15:33 PM

Umm, only sort of. It would wind down after a while (or spin the Earth back up) due to conservation of angular momentum. You are postulating a situation that is more or less permanent due to an ancient collision or the tidal effects of an orbiting moon, and over billions of years the conflicting motions would equalize.

"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"
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