Other speculative evolution projects exist, some of which have had considerable effort put into them.
Epona includes contributions from Martyn Fogg, Paul Birch, Geoff Landis, Gerald Nordley and Gert van Dijk, among many others;
Gert van Dijk’s Furaha is impressive for the work of mostly one person;
The world of the Birrin by the artist known as Abiogenesis is very well realised, and represents a type (the centaur) that might be more numerous than erect bipeds, if not cantilevered bipeds.
By the way, I thought I’d add a speculation we had in another thread about under-water intelligence. I think the biggest limitation is not technology like fire and chemistry: the biggest problem is oxygen. Human brains use tons of oxygen, and they do it at a high temperature that facilitates fast chemical reactions. Water just doesn’t hold that much oxygen even at low temperatures and if you want a high body temperature, you either need warm water (with less oxygen) or you have to burn even more oxygen to regulate your body temperature.
Again, I wouldn’t rule out an aquatic intelligence entirely… but if we did have one, I wouldn’t be surprised to see a reliance on air breathing. Something like a dolphin that already breathes air, maybe, or one of those fish that can gulp air to compensate for bad water. This adaptation, in turn, makes it easier for them to get around on land eventually. (Great, now I have an image stuck in my brain of a dolphin in a wet suit riding horseback).
I am reminded of Olaf Stapledon’s influential work of speculation, Star Maker. Just about the most advanced of all his (very varied species) was a symbiotic relationship between a whale-like creature and a crab-like creature; the crab component of this relationship became increasingly amphibious, allowing the development of fire and other air-dependent technology.
A second limb.
Life forms with a single prehensile limb could not develop any form of technology. All they can do is to pick up and use existing objects, such as a stick or a stone.
Ape-like creatures can learn to use more sophisticated tools. Start with holding a stone in each hand, hit them together. Sharp bits break of, which can be used as basic knives. Hold a dead animal in one hand, and your knife in the other. Remove the skin. If you wrap the skin around you, then you can survive in colder areas. Elephant-like creatures could never do that.
Elephants with two trunks could.
Twin trunks might seem unlikely, but here is an organism that might have evolved into something of that sort, given a different set of circumstances.
We ARE talking about aliens with an advanced civilization here right? Not just any alien life-form which can swing a stick or something? Because no creature, no matter how intelligent, is going to traverse all stages of development from prehistoric stone age all the way through industrial revolution and space age technology with just* a trunk. *
There are other reasons too, such as their dietary needs and the bulky mass of an elephant working against the ability to adapt to new or changing circumstances and sustain a large population. Humans got were they are now by being flexible in more than one sense of the word.
I think this is incorrect.
Trunked animals could come in a large range of shapes and sizes, as in fact the elephants have in the past. Small elephants not much more massive than a human were living on Malta not very long ago.
Sentient animals which use a trunk, or more than one trunk, or a branched trunk, may be as common as erect bipeds - so far as we know.
Which part are you disagreeing with?
Sentient, maybe, but not sapient. Nobody is disputing that elephant-like creatures will probably evolve separately all ove the Universe. But it’s doubtful that they could ever be sophisticated tool users.
I’m sure the people living in Denver would like to hear about that, as their air pressure is about 85% of sea level, which would make the oxygen partial pressure there about equal to 18% at sea level.
If there’s less oxygen in the air, wouldn’t you just breathe faster to compensate?
I think it’s reasonable to assume that alien intelligent species would also breathe oxygen at reasonable temperatures, as breathing oxygen and using water as a solvent seems to be the most efficient way to accomplish these tasks.
I wonder how things would work out on a planet with a much heavier or much lighter inert gas atmosphere. (Earth seems to be the only planet with a whole bunch of nitrogen and a significant amount of argon.) Would the oxygen partial pressure stabilize at a level similar to what we have today on earth? I guess it could be a good deal lower, but probably not too much higher; we’re already in the situation that a lot of material will burn if it catches fire, oxygen is too reactive to be even more available.
We know that most planets have a lot of carbon dioxide but plants will happily turn that into oxygen. I would assume that carbon monoxide would either be used by plants or oxidize into dioxide, so not worried about that.
No, it is not.
A species could develop an advanced civilisation so long as it has three attributes;
a sophisticated brain or an equivalent array of processing tissue; manipulatory appendages (preferably more than one, but one could conceivably suffice) and some form of communication between individuals.
Remove one of these attributes and you probably won’t get a civilisation; if all three are present it still isn’t guaranteed, but the potential is there.
Some planets, especially around red dwarf stars, might have very dense oxygen atmospheres. If there is nothing to burn or oxidise on the top surface of the crust, the oxygen could build up to an arbitrary extent.
Worlds like this are sometimes called ‘mirage planets’, since they might mislead observers into expecting an Earth-like environment; but an atmosphere too rich in oxygen would probably be inimical to life.
But where would all that unbound oxygen come from? We see a lot of ice and some carbon dioxide in the solar system, but not oxygen. Presumably, any oxygen formed in a star would react with elements like hydrogen or carbon as soon as it cools down from plasma.
What could probably happen is for high energy radiation to split up water and then for the hydrogen to escape into space…
I guess a planet either has a lot of oxygen OR a lot of stuff that will burn, but not both at the same time. So either too little or too much oxygen would make vertebrate-like life very hard to impossible.
Reading the link from NASA provided in my previous post, it seems the theory is that any water on the planet could be dissociated by the sunlight and UV flares of the local star, creating hydrogen and oxygen; the hydrogen escapes, because it is lighter, but the oxygen remains.
I can imagine a very broad range of circumstances here; many planets of this kind will absorb the oxygen into the crust, leaving nitrogen and carbon dioxide; planets of this type will resemble Venus. Other worlds will retain enough water to have an ocean covering its surface, and also retain an oxygen-rich atmosphere. Many waterworlds might be something like this; a very few might accidentally have a breathable atmosphere, despite never bearing life.
One interesting set of worlds could retain helium, but not hydrogen; these worlds might have breathable atmospheres, but your voice would sound really weird.
Turns out that nitrogen is actually quite common throughout the solar system. Even though it’s a small percentage of Venus’ atmosphere, Venus has four times as much of it as the earth, and it’s also found on Titan and Pluto, and in the form of ammonia in the atmospheres of the gas giants.
Also, apparently Venus and the earth started with similar atmospheres, but the earth had water that dissolved the carbon dioxide which would then be absorbed into rocks.
So if oxygen partial pressure is limited by its reactivity, then a planet with abundant water at the right temperature will very likely have a breathable atmosphere, although if the pressure is too high (> 4 bar I believe) you’d get nitrogen poisoning.
Have you ever seen what a one-handed human can accomplish? It’s pretty impressive, and we’re a species that relies on having two.
An elephant would still be able to shape stone tools as just one example of technology they could achieve. They could even achieve some more complicated procedures with multiple elephants working together. Human surgeons don’t have eight hands, but they do have the ability to get three assistants to help them.
You also have to consider selective pressures here. Let’s look at humans again. Chimps are lousy at throwing objects because of the structure of their shoulder. Humans got smart enough to use skill in throwing objects, but we also better than chimps because we have a shoulder adapted for that purpose. Intelligence (enough to throw rocks or spears) presumably came first, then the people with the better shoulders were selected for.
Applying this to elephants, as time passes, it’s entirely possible for selective pressures to favor elephants with more “fingers” or maybe even something revolutionary like an elephant with two trunks. (Just like some humans have six fingers; it just turns out that six isn’t really helpful.) Given a couple million years of selection and I think you’d see that intelligent elephants do damn well with a single trunk and have a small (but not zero) chance of multiple trunks.
Yes, I have, and they use objects created by people with two hands.
As an example, a hunter making a spear, he could hold a stick in one hand, and the other hand use a flint knife to sharpen the end into a point. A one-armed man could put the stick in a vise, attached to a sturdy workbench. But he would need someone else to make the vise and the bench. An entire race of monobrachoids starting from scratch would find it difficult.
How?
What about fire, the proverbial rubbing two sticks together? Could that be done by a race of one-limbed creatures?
That sort of co-operation requires a sophisticated language. This did not happen on Earth until about 2 million years *after *the first tools.
What other clades could pull it off here, I wonder?
Elephants of course have their trunks-would it be too much bother to have the ends evolve fingerlike extensions for finely dextrous tasks?
Another primate might come along…what made our ancestors distinct from those apes which didn’t evolve the way we did? Living in the open, vs. trees? Just how much of an accident was human intelligence?
19% is ideal, you can (obviously) get by on less
No, because the breathing reflex is triggered by carbon dioxide levels, not oxygen levels.
Lower oxygen levels are compensated by things like an increase in red blood cells. There are other mechanisms as well, some common to all people and some requiring specific genetics. People can adapt to a lower partial pressure, with people seeming to adapt quite well up to 8,000 or so feet. Some groups with specific adaptive traits (like Tibetans) live up to around 14,000 feet. Clearly, it’s conceivable an intelligent species might evolve in lower oxygen levels than we have if you take sea level pressures as normal.
“Rubbing two sticks together” is not the only way to obtain fire. Obtaining from natural sources, and by striking sparks, are just two.
Really? You’ve found fossilized words?
There is no way to prove the veracity of that statement, as we have no clue when “sophisticated language” arose.
I suggest you get some books on prehistoric living and read what it took for humans to survive against all odds… how adaptive they had to be to be able to get food from every possible source, how adaptive they had to be to physically adjust against any demands the environment put on them. The notion of a diet-restricted quadruped colossus (or even room sized creature) to accomplish anything close with a single sensitive tentacle which can lift objects by squishing its ends is madness…
I can already envision elephants making spears with just a trunk. Carefully knapping spearpoints… with a trunk. Wrapping binding around the point and attaching it to a shaft… with a trunk. Throwing it without binocular vision… with their trunk. And they can’t even eat the meat of their prey! Oh well at least they can sow clothing from the fur so they can expand their empire even further into cold regions! Sow clothing, with a trunk…
No sorry, we are going to have to agree to disagree here. Frankly I think you are being overzealous in your belief that intelligence is the main limiting factor. I don’t understand why, perhaps you really like elephants. Perhaps you watched too many old scifi movies. I like them too, but solely for entertainment.
Frankly if you took a human and chopped off one arm, removed the hand from the other arm, and left them with some bulges of muscle on the end that they can used to squeeze and hold light objects with, they aren’t going to be very good in the manual labour department. Let alone fine engineering. Now imagine genetically engineering a few thousand humans this way and tossing them back into the stone age… oh yeah and they are all strict vegans, aren’t capable of jumping or climbing or deep diving and have bad eyesight. Not that this matters match since they can’t look ahead of them anyway. Good luck with that.