Aqueducts, Roman aqueducts, were certainly NOT one of the first things which were constructed when the Roman’s arrived.
Aqueducts required immense sums of capital to build and were only constructed when demanded by necessity (and if modernity is any example, only built far too late to satisfy demand). Frontinus himself tells us that Rome’s first aqueducts were only financed through the soils of war (eg. Pyrrhus, Carthage, etc).
Toys with wheels have been discovered in pre-columbian excavations.
But I find the “no beasts of burden” argument specious. They had llamas!
Just had to double check my photos, but the Mycenaeans had bridges with what looks like an arch to me. Here’s an image.
Llamas were only in the Andes – they were unknown in Central America. AFAIK, those wheeled toys were only found in Central America. So the two never got together.
My understanding is that llamas are good pack animals, but their anatomy around the chest makes it very difficult for them to pull anything.
Perhaps the wikipedia link was not clear (thogh I think it adequate): the Roman arch is superior because it has an odd number of stones. This is much easier to construct than previous arches, which had an even number of stones and were less sturdy. Roman arches, for example, could be built without any mortar provided they were under pressure, though they did usually use it IIRC.
That is true, yes, but it’s a feedback mechanism. They can do a thing, so they do it more, so they do it better. There’s no ultimate reason for it except that people can and choose to do so. If you want an “answer”, you’d have to go back and ask the Romans themselves, and it would amount to mostly being, “But… it’s an arch/ Why not build arches?” It’s the same reaso people build skyscrapers or even just make them with glass sides. There’s no accounting for taste.
More to the point : they had people. Slaves. They were, arguably, more compassionate about them, gave them more rights than the Romans or Greeks did… but a slave is a slave.
Quercus said:
Good gravy, it’s not like Asians and Europeans started with ideal harness designs. Their first methods would press against the cattle’s throats and choke them.
I think their are a couple reasons that depend geographically. The “didn’t have beasts of burden” applies more to plains folk. Whereas the llamas are native to the Andes mountains. Mountains are not ideal terrain for wheels.
Or maybe, it just didn’t dawn on them. 
That may explain how they transitioned from wood to stone but it still does not explain why they did not evolve stone arches. If I can draw any conclusion from the Greeks’ apparent distaste for experiment, for example dropping two objects to see if the heavier one does in fact fall faster, then it would be that they somehow, for some mystical or philosophical reason they preferred their lintel/beam method.
Another point - the Greeks had plenty of marble and limestone and used that in blocks for construction - so they could build post-and-lintel construction easily, and working with large long chunks of rock made more sense than carving small pieces, since each face required hours (days?) of work.
The Egyptians likewise had limestone and could cut large blocks which worked as well as wood. We see that in fact, the block size went from bricks a foot or two in the Step Pyramid to blocks 4 by 4 by 6 feet or bigger. The formed bricks they worked with were mud brick, with strength qualities not conducive to anything except stacking.
The Romans originally worked primarily in terra cotta brick as much as stone block- bricks and mortar were easy to shape into arches, with a wood form. Once set, it was sturdy and self-supporting, provided as previous posters note, the end pillars were buttressed by walls or the lateral force offset by another arch. (Many of the “Greek temples” in the Hellenistic world, and the pseudo-Greek architecture in -for example - Pompeii are brick stack columns coated with plaster to look like the marble columns “back home”. For less load-bearing construction, such as aqueducts, I assume the Romans graduated from bricks to carved stone once they were rich enough to graduate to stone-work as a regular matter of course. Plus of course there would be better timber resources for arch forms in the Italian peninsula, than in Greece (need to import from Lebanon?) or Egypt.
Greek temples are fundamentally wooden buildings, using artificial wood made out of stone. One of the obvious problems with stone arched buildings is that they don’t look natural if what you are trying to achieve is the look of a wooden building.
I know so little about architecture or construction, that I’m embarrassed just to ask questions. Images of ancient Greek buildings show lots of pillars but very few doorways: Is that because they lacked the Arch?
It seems to me that the arch was rather a non-trivial idea. Just the invention of the keystone represents much more creativity than in the majority of U.S. patented inventions, I think.
Greek temple architecture employed lots of columns because that’s how you built a Greek temple that looked like a proper temple. There was a load-bearing purpose to the columns but they were massively over-engineered, their capitals ornamented and their massing, proportions and designs were subtly refined to create specific effects and reach for beauty. Practical experience of arches seems to have come back with the Macedonians around 400BCE but the Greeks kept building proper temples. Arches did get used in other types of building after that date.
If the aesthetics or functionality of temples had changed then Greek architect-engineers, who learned their stuff by jobbing all over the place, from masters throughout the Greek world would have known from then on that arches could be used as one solution to solve a specific problem. Essentially that problem never came up so there was no need to do it.
Don’t confuse knowing how to solve a problem, and knowing how to avoid having the problem in the first place. Greeks knew exactly what they were doing, and it was just fine. Their architectural design was not static, but traditional forms did not need changing, and arches were adopted for other purposes [just not flashy aqueducts].
There are natural rock arches all over the world, so it’s not a big leap for someone to think, “I want to build something like that”.
I don’t think natural arches have keystones.
And there’s a difference between admiring an aesthetic form, and deriving it as the solution to an engineering problem.
Given that no one seems to have anything like a factual answer, I’ll hypothesize that the principal factor is economic might.
If we assume that arch construction is either more costly (particularly using the techniques of the Etruscans) or that structures of size large enough to require arches are more costly, then the culture which has more financial might to bring to bear will end up being the one to use more arches.
One might also note, along this vein, that one of the most famous “arches” in the ancient world is the Pantheon Dome, in Rome. This was designed by Apollodorus of Damascus, a Greek. He also built a number of triumphal arches for Trajan.
One might suppose that once some nation gains enough financial might to build giant structures that they’ll also be able to attract the best talent from far and wide. This leaves their homelands deprived of that genius. So if everyone competent enough to build an arch left to go to the place where arches can practically be put to use, we would see what we see.
Damn, for a moment I thought ralph124c was back, but it’s just a zombie. 
The Egyptians did use arches: File:Egyptian vignettes luxor.jpg - Wikipedia (example from the Ramessuem, so way older than the Parthenon). They just didn’t use them very often. I think it is safe to say that Ancient Egypt was rather conservative in architecture.
Greek temples kept the same archless form for a long time because that’s what a temle was supposed to look like.
I do remember seeing an arche in the entrance to the stadium at Archaia Olympia, but I don’t know if it is from the Roman period.
Maybe no pack animal wagons, but I’ll bet they could have used the carrying capacity and weight leverage of a nice, big wheel barrow.
But this goes to my point. The Egyptians and Greeks had plenty of stone material to make large, long lintels. AFAIK, most of Italy is soft volcanic rock, making it easy to dig catacombs but not terribly useful for flat rock pieces spanning ten or more feet. Until they expanded north to Carrara and it’s marble, a lot of construction was bricks. So like the Ramsesseum example, a lot of bigger openings and spans in Roman construction was brick until they could import better stones. Arches have different stresses than lintels, specifically they are mostly compression (which works for softer rock) rather than bending forces which more easily break a lintel.
So like a lot of technology, you work with what you have.
