On another thread I hinted that a world's geography might either help or hinder technological development. Since this thread is if anything even more speculative than the notion of spacefaring extraterrestrial life itself, I will be less bold in my speculations than on that other thread. However, I think a few themes may be consistent. My ideas are heavily influenced by Jared Diamond's book Guns, Germs, and Steel, which seeks to answer the question "Why did Eurasia in general, and northwest Europeans in particular come to dominator the globe?". The short version of Diamonds answer is:

*Eurasia is a huge land mass with an east-west orientation.This not only made it easy for certain plants and animal species to spread to other areas with roughly similar climates, but the large land area itself increased the probability that human-friendly grains and animals would evolve in these regions in the first place (contrast that with the Americas and Africa. Though both are large, they also have a north-south orientation, which made it difficult for plants and animals to migrate from one region to another).

*Europe's Climate was ultimately more conducive to Agriculture than many other places.Though North Africa and Southwest Asia were the first to develop the agriculture and herding necessary to sustain the first civilizations, the "Mediterranean" climate tends to be a fragile one in the long run, given it's semi-arid conditions. Furthermore, the semi-arid condition itself encouraged irrigation, which is proven to ruin cropland by depositing salts onto the soil. Northwestern Europe may have been a latecomer to civilization, but its moist climate spared it the trauma of Mesopotamia and the Mediterranean basin (including Southern Europe).

*Europe's geographic fragmentation. China likewise benefits from the above points as much as Europe did. In fact, it was the world power before Europe came on the scene. China's problem is that its lack of geographic obstacles encouraged political unification of the territory early on, removing the incentive to develop technology before "the other guy" did. Europe, divided by mountains and large fingers of seas, more or less predisposed it to political disunity. These barriers were great enough to foster political disunity and technological competition, yet not substantial enough to stop an easy flow of ideas from one place to another.

With the above in mind, I will offer some initial reactions about how this could apply to other planets that might contain sentient/intelligent life.

Life-bearing planets around red stars - as discussed on the above length thread, planets in the habitable zone of a red star's solar system are at least fairly likely to have one side of the planet in perpetual day and the other side in perpetual darkness, causing one side to freeze and another to fry (although this is by no means guaranteed for all such planets). But even for planets which this is the case, the twilight zone is at least somewhat likely to harbor life, given all other conditions are favorable.

However, because the twilight zone is, by definition, narrow, I suspect that such a planet will have at least as difficult a time developing advanced technology as the Americas and Africa did in pre-1492 times for one, possibly two reasons

(1) the north-south orientation might make it more difficult to transfer plants and animals along the planet's twilight zone (although it just might be possible that the sun's constant angle at the twilight zone might render the entire twilight zone with less temperature variation than on earth, but this can't be counted on)

(2) Even if the counterclaim of (1) is in fact the case, the fact remains that the twilight zone's land area is quite small, therby reducing the probably number of plant and animal species available to any sentient inhabitants living there. This would seriously limit the potential energy supply gained via animal power and reduce the potential nutrition value of the planet's food supply. Furthermore, this reduces the probability that certain metal ore deposits (especially those not dependent on the presence of life) would not be available in the planet's habitable areas.

These are at least two reasons why develpment of advanced technology might be hindered on a life-bearing but rotation-locked planet revolving around a red sun. For similar reasons, I believe a planet with too great an axial tilt would render unusable much of a planet's surface near its poles and even mid-latitudes for at least a hefty portion of its year. I freely grant that the local life just might be able to adapt to these (by Earth standards) wild extremes in temperature and likely percipitation as well. Even so, the greater variation still places an extra burden on any inhabitants of such a planet that we simply do not experience here on Earth, and thus (IMO) increase difficulties of exploiting the planet's natural resources. This also could well hamstring a planet's technological development - regardless of the color of its star.

Moving on to planets around Orange, Yellow, and Yellow-White suns that happen to actually bear intelligent life...

Even assuming liquid oceans of any sort (water or otherwise) cover a favorable portion of the planet's surface -- 40 to 80%, the continents' position and orientation still plays a role, for all the reasons described above. Ideally, the planet would have a large continent with an east-west orientation centerend on the mid-latitudes (which Eurasia qualifies): width for rough climatic similarity and mid-latitude to offer a happy medium between cold and warmth. This is especially true if the main solvent were water (on earth, tropical rains are notorious for leaching nutrients and needed minerals from soils). A large east-west landmass astride the equator would be fairly likely to allow transfer of plants and animals, although the lack of climatic variety compared to the mid-latitudes will likely mean a smaller variety of possible plants and animals species that may evolve on such a continent. Ditto for large continents astride poles, even if these places happen to not be "frigid wastelands" from the locals' perspective (even a pleasant pole-centered continent would still lack a variety of weather. For these reasons, I believe Eurasia-type landmasses are the most conducive to sentient development and the transfer of knowledge, goods, and services.

Ammonia or other solvents might operate under a different principle (i.e. the best soils on these worlds might actually be in its tropics, or even its poles), though I won't speculate further about this particular substance. Regardless, I think a planet without a land mass that allows both favorable growing conditions and ease of transfering plants and animals across that land mass would undoubtedly hinder technological development, no matter what its biochemistry happens to be.

If there are no large continents as such, but a few patches of dry ground scattered somewhat evenly across the planet, the problems are even worse. Small land masses will likely mean less fertile soils, less above ground resources, and hence less population necessary to achieve the critical mass necessary for rapid development of technology (on Earth, Polynesia is such an example). In fact, it's doubful whether many potentially habitable (by local standards) land masses would become inhabited at all.

Too little ocean surface (under 20% or so) likely renders much of the planet uninhabitable due to the short supply of precipitation (water, ammonia, or otherwise). Since we can assume all life forms to evolve to depend on their local solvent, I think any lack of sufficient precipitation is likely to discoruage life's growth. Therefore, as with the hypothetical rotationally-locked planets around red stars, large portions of a small-ocean planet will be rendered useless or inaccessible to the local population (in fact, the non-twilight zones of the rotationally-locked planet are deserts - A superhot Sahara on the day side, a super-cold Antartica on the night side).

For the above reasons, I believe that, barring exceedingly radical differences in the life-sustaining processes, most, if not all, inhabited planets with high techonolgy will have roughly the same geographic layout as Earth:
*A large mid-latitude continent with a noticable, but not extreme change in seasons
*A moderate axial tilt (between 10 and 30 degrees) to create convincing, but not excessive, seasonality
*A rotation period slow enough to allow heat buildup on the day side but fast enough to keep one side of the planet from getting too warm (and vice versa for the cold side getting too cold).

Again, it's certainly possible that the local life would adapt to these conditions (in fact, I'll grant its fairly probable). Even so, the very need to adapt to these extremes does make the business of living itself at least somewhat more difficult. After all, adaption to hostile climates takes time and natural effort. This robs the organism of energies that could otherwise be put to use growing more and better food, breeding better animals, and the leisure time necessary for speculations about the nature of things (the ultimate source of science and technology itself). Although it's ultimately difficult, if not impossible, to speculate about the probabilities of X number of worlds with Y tilt and Z orientations/sizes, it would be wise to consider that the greater number of inhabited worlds, the greater the probability that thier homeworlds would suffer from at least one of these disadvantages, even if it turns out that such extreme enviornments would not hinder VERY VERY long run technological development.

One other possibility is that a resonance develops, like Mercury, which does not have one side continuously facing the Sun.I think that is known as the Tiny Anthropic Principle

[quote=hhEb09'1]One other possibility is that a resonance develops, like Mercury, which does not have one side continuously facing the Sun.[quote=filrabat]

Certainly this is possible. However, I would argue that an otherwise life-friendly world with this rotation period would actuall make civilization less likely to evolve because any one point on the planet would still suffer from alternation of too hot and too cold. Unlike a rotation-locked world, there would be no part of the planet with a stable temperature regime. At least where liquid solvents are concerned, they would almost certainly alternate between a gaseous state and a frozen state at some point in their rotation period ("day")

I thought that too, but on further reflection decided it may not be so anthropic after all. Atmospheres follow the same essential physics, though many local factors will likely influence the patterns. Basic pattern: Hot air rises and cold air falls. In planetary terms, Hot air will tend to rise over the hottest part of the planet and fall at the coldest part of the planet. On worlds with rotation times half to double earth's that means air rises at or near the equator and falls at or near the poles (Yes, planetary rotation will introduce convection patterns much more complicated, but for now for simplicity's sake, let's ignore that). Because of this convection

Atmospheric convection patterns
*I think most consistently warm areas will tend to be moist, regardless of the planet and it's local solvent (because hot air cools as it rises, and hence is less able to hold moisture)

*Likewise, falling air tends to warm. By the time the air falls, it's likely to be very dry, and hence less likely to produce rain. Air at the poles tends to fall, which is why polar regions on earth are deserts. Barring a very strong axial tilt, I see no reason why this wouldn't be true of other planets. Even so, I think a very strong axial tilt will reduce the technical viability of a world for the reasons listed above.

Ocans of Local Solvent

Water oceans may be cooler in the summer and warmer in the winter relative to land, though this might not be the case for other solvents on other worlds. Regardless, it is highly likely that some kinds of temperature differences between sea and land will be present (which plays no small role in precipitation patterns). Surely this must render some areas of that planet more suitable to its inhabitants than others.

Land and Continents

The larger the land area, the more likely it is to give rise to many species useful to the local sentient intelligence, all other things being equal. Furthermore, the greater the variety of different species one has access to, the more benefit the civilization gains from its natural environment. Therefore, areas with strong transportation and communication links are more likely to introduce a huge variety of species into any one civilization - with benefits for the dominant species highly likely.


So while the details of oveall geography are likely to be different from living planet to living planet, there are certain rules of physics that render some basic patterns the same, regardless of the type of ecosystem. This, in turn, means that nature will play favorites with certain areas of a planet. Hence, it seems that a planet with a large body of land that allows widespread propagation of various species will be more likely to develop technology quickly. It strictly doesn't have to be a Eurasia-type body, but it does have to facilitate ease of transport and communication.

I'm sure that doesn't follow directly. You seem to be basing your calculations on a simple map of insolation, but we know for sure that that is not completely valid. But even ignoring tilt, there might be areas near the poles where the insolation was "perfect."I don't think we can ignore that, since the one close example pretty much is much more complicated than that.

I think that alternating seasons in temperate places made humans smarter. You have to cope with an ever changing environment. This impacts the way you conceive technological (in this case agricultural) tools and methods. This could explain the underdevelopment of the tropics, among other things.

I don´t think I agree with this assertion, since the tropical climate is very friendly to most vegetables. Famine was not a problem for primitive Americans.

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As near as I can tell, there is absolutely no evidence whatsoever that that is true.Now, that could be true. I know I don't get a lot done, at the beach Hence, perhaps not a need to develop the methods of agriculture. Ease of growing, and hence gathering, as in "hunters and gatherers", doesn't necessarily translate into the study of agriculture, or at least not so much.

Is was once their agricultural methods had turned the place into a desert.

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It is probably true that geographic factors are extremely important (or in some cases absolutely vital) not only for technological development, but for life as such. I too found Diamonds book very thought provoking, but I think there is some extremely important factors he ignore, especially when it comes to the question of european domination at a certain era in world history.
Those factors have to do with communication and transport.
1:Some geographers speaks of a land and a "ocean" hemisfere with Europe located in the middle of the first.
It is also located centrally, between Asia and Africa(Though the middle east is even more so.) That means good communication opportunities in eras before ocean travel - all of human history except the latest few centuries.
2: A very large part of Europe is coastal land, which had an extremely stimulating effect on sea transport.
Sea transport was practically the only form of transport, not dependent on humans or animal power before 19.century (perhaps with the exeptions on some very limited use of winds and streams on rivers and lakes). Europe and its civilisation dominated the world by ruling the seas. Mostother large regions of the world have far less favourable conditions for developing sea communication, because of relatively small coastal zones, because of huge distances to other continents or larger isles along most of the shores, and perhaps also fewer good places for harbours,and difficult transportation conditions to the interior(mountains and desserts).

I could well be wrong, but the only way I’m aware of that life could survive on such a very slow rotating world (especially if it’s day is longer than a week, and almost certainly two weeks) would be for the planet to have both a very slight axial tilt AND a moon whose regulatory power over that planet’s axial tilt is comparable to that of our moon’s power over Earth’s tilt (i.e. a very slow change in tilt, if at all).

Let’s imagine a slow-rotating planet in the HZ of a red sun, with an average 10,000 year temperature comparable to Earth’s AND an axial tilt similar to Earth’s. However, let’s say its “day” was 192 hours (exactly 8 actual days).

I will use a daily warm-up rate that is very likely to be highly underestimated: an average of 0.5 C (0.9 F) per hour. On real Earth, the day warms up typically between sunrise (say, 6 am) to about 3 pm: 9 hours, or 37.5% of the rotation period. For our hypothetical world, that translates into 72 hours of warm-up, with the remainder of the rotational period radiating that heat back into space or the ground or oceans. This translates into typical global diurnal temp difference of 64.8 F (36 C), all other things equal to our Earth. I would think that a high of 30 C (86 F) and a low of -6 C (21 F) every week would be a bit stressful on life. Although I don’t think it would be impossible to adapt to, I also think that the business of living more difficult because the life has to expend extra energy protecting itself from such a strong temperature change for every one of (our) weeks/ their “days”. At best, I think this would render a huge portion of the planet barely habitable, if at all (with all the subsequent hampering of civilization/technology development I believe would follow). Naturally, it’d be even worse for a 400 hour “day” for that planet (barely survivable, if at all). Unless the planet was lucky enough to have the axial tilt and moon configurations I alluded to, I have a difficult time seeing how advanced life could survive on a world with a two-week day (though as I said above, survival on a one-week “day” world is somewhat conceivable, providing the axial tilt is not too steep).

NOTE: In this quote, "that" means "other factors besides the simple air rises when it's warm and sinks when it's cold - as in air rising at the equator and sinking at the poles"

I only made the “ignore” remark in order to set up one small aspect of the explanation, rather than throw too many details out at once. However, I will move somewhat beyond the simple level.

Here on earth air masses that rise at the equator usually fall back to Earth near 30 degrees latitude each side of the equator, along with the mid-latitude air mass (Hadley Cells). As at the poles, falling air at 30 Deg N/S is dry - hence such areas are often deserts, unless they are on the eastern sides of continental land masses (East Asia, SE United States, etc.). Polar Hadley cells also occur near both 60 degrees latitudes, where both the mid-latitudes and polar air masses rise, which causes frequent storms if they form over an ocean (Far N. California to SE Alaska, NW Europe, etc). Though most of the air in the subtropical and subarctic Hadley Cells returns to the poles and the equator, some of it does move into the mid-latitudes.

Further complicating matters is the Coriolis Effect. This causes the what little air from the tropics and the poles that slips into the mid-latitude air mass to be deflected in the direction opposite the planet’s rotation. Complicating matters yet further is the fact that continents heat up and cool off faster than oceans, further complicating air-flow patterns.

Unfortunately, for the sake of our other planet, I could not find out to what extent or degree the location of Hadley Cells would change if the axial tilt or rotation speed changed. This would certainly be an interesting offshoot into speculating about weather patterns (and hence a large part of livability) on such a planet.

NOTE: Yes, I apparently broke my promise not to speculate too strongly about planetary weather. But I just couldn’t resist.

Sources: Wiley College ,
Georgia Perimeter College
Scienceclarified.com

If anything the pre-1492 India was more conducive to diseases than pre-1492 Europe was. Warmer climates combined with less seasonal temperature variations tend to favor more bugs of both sorts (germs and their carriers). Yet, India developed civilization a few millenia before NW Europe did. Even Ethiopia developed civilization before Europe did. Furthermore in the Dark Ages, West Africa was ahead of Western Europe. Each area had its own challenges to meet.
Western Europe is actually fairly mild in the winter thanks to its western continental margin-with-midlatitude location. On top of that, its seasonal temperature difference are fairly narrow by world standards. It's not palm tree country, but it's no Russia or Central Asia either. Furthermore, soils in mid-latitudes usually don't lose their nutrients nearly as quickly as in the tropics, and even the subtropics.



I don´t think I agree with this assertion, since the tropical climate is very friendly to most vegetables. Famine was not a problem for primitive Americans.[/quote]

What about grains and livestock? They provide many more proteins and calories per gram than vegetable do. Furthermore, you don't have to hunt livestock, which means more food/nutrients per hour of labor and/or calories burned.

Where our hypothetical other planet is concerned, I suppose you can create a scenario by where the less fertile/less temperate/etc. areas just happened to be home of the plant or animal that brought forth the most striking improvement in the planet's condition. Regardless of climate and soil type, I think the most likely places for civilization to develop on such a planet if it has a large landmass oriented perpendicular to global temperature boundaries, yet large enough to permit a wide variety of climates within its main land mass. Short of that, it would have a geography that allowed for quick transportation and communicaiton throughout an enormous portion of its liveable area.

One question about the origin of technological civilisations (and of intelligent beings and their spread) is if it is a function of time and "evolutionary" progress. Or rather very dependent of the right external conditions, not the least the right geographical ones. Since the geography of earth has changed extremely it could be that we live in a special favourable geographical and environmental "situation" for beings like us. (a very important factor making us possible)

Now you´re implying that the tropicals are lazy [we don´t have any evidence of that, either].

__________________
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Inside out, outside in - Perpetual change." - A British rock band

Not at all. At least, it wasn't my implication. I was just conceding that you might be right. Another way of putting what you said, I think, is necessity is the mother of invention*. If you don't need something, why invent?

*I guess it would the inverse: if it's not a necessity, it won't father invention

Yes, I agree. That´s what I originally meant.

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I'll bite: how old is civilization in Ethiopia?

...And in West Africa?

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I don't mean to sound glib, but I am pressed for time. Therefore I will simply tell you to read the following Wikipedia articles

History of Ethiopia, Ghana Empire and Songhai Empire.

I will let them suffice for my reply