[annie123 (OP)]

Just listened to a Discovery podcast about the new Science exhibit at the British Museum focussing on Indian science. That there were civilizations there 5000BC that had cities with household running water, wastewater disposal and other technologies not repeated till the Romans was described, along with standard weighing systems etc.  But nothing was said about what happened to these developments- why India seems to have slid backwards rather than forward until the last couple of centuries. SO - any ideas how civilizations lose their momentum?  or any record about the Indian situation?

[Colin2B]

It is currently thought that climate change - drier climate - affected agriculture and there was a reduction in trade with Egypt and Mesopotamia, slowly people abondoned the cities.

There was also a mini technological upsurge in Roman 1st century AD eg mini steam turbine, but they seem to have been considered novelties rather than leading to an industrial revolution.

[evan_au]

I recently visited the archaeological site of Akrotiri. Around 1600BC they had hot and cold running water in houses and plumbed sewage.
What happened to them is easier to see: the town was evacuated after a series of earthquakes, and then the volcano blew itself to bits, leaving a big hole, and a layer of volcanic ash tens of meters thick over most of the island.
See: https://en.wikipedia.org/wiki/Akrotiri_(Santorini)

I also saw the Antikythera mechanism, dating from around 100BC. There have been several attempts to reverse engineer the encrusted fragments which remain; by a complex series of gears, it could have predicted the motion of the Moon and planets with amazing accuracy for the time.
There were apparently accounts of such devices from ancient times, but they had been dismissed as fantasy.
https://en.wikipedia.org/wiki/Antikythera_mechanism

Works of art and machines of science tend to rust away to nothing if made of iron, or get melted down and turned into weapons for the next war, if made of bronze. So the most enduring remnants tend to be made of stone or pottery - and these don't tend to be the society's most complex achievements.

[Colin2B]

Works of art and machines of science end to rust away to nothing if made of iron, or get melted down and turned into weapons for the next war, if made of bronze.

I'm always impressed by the sophistication of early jewelry, particularly bronze age. Not only have archeologists found sketches on pieces of bone - is this what you had in mind sire - but the techniques used were very sophisticated. For example, they did not know how to facet precious stones so in order to get the reflections they stippled the base of the holding depression with extremely fine and closely spaced indents like pin pricks, this required not only very fine tools but a great deal of skill. I ssuspect some of the jewelry makers were shortsighted which allowed them to work with very fine detail.

[jeffreyH]

If there were some extinction event that took out humanity it wouldn't take that long for all traces of us to be eroded away.
http://discovermagazine.com/2005/feb/earth-without-people

[Giles Farnaby]

I take it the podcast was referring to the Indus Valley Civilization. There is a solid summary of the issue, from a linguistic and archaeologic point of view, in Michael Witzel's "Early Indian history: Linguistic and textual parametres".

But even the best specialists are not yet sure about the reason(s) behind the collapse, and whoever claims to be sure is not a specialist in the matter.

Now, some of the things you wrote about are subject to economies of scale (ie, it may be efficient to construct a running water system for a city, it may not be for a pre-historic town) and there is also the discoveries and/or inventions for which no market developed (oil was known to the ancients and the Greeks had a steam engine called aeolipile).

For a somewhat falsifiable thesis about why civilizations collapse you may take a look at "systems theory":

[Search for "Collapse of Complex Societies by Dr. Joseph Tainter" on Youtube, since I can't post links]

Finally, we have a case of several civilizations disappearing but leaving more traces than the Indus Valley Civilization left: it is called the "Bronze Age Collapse" and this lecture by Mr. Cline will surely teach you (if you haven't seen it yet) the fundamentals of crashing down at that time and age:

[Search for "1177 BC: The Year Civilization Collapsed (Eric Cline, PhD)" on Youtube, since I can't post links]

[annie123 (OP)]

Thanks everybody for thoughts and suggestions for further info. which I am following up with some interest.I  also read Jared Diamond's Collapse some time ago. Many years ago I read Canticle for Leibowitz by Walter Miller which describes in fiction what might happen  to our civilizations after a nuclear holocaust - perhaps I should read it again in view of present politics. I  guess the Indian example made me wonder why, when such exhibits are described, there is often no further comment about that particular situation's decline included in the report.

[puppypower]

Another possible reason old technologies fade away is; successive generations, who know how to use the technology, have no clue how to maintain, reinvent or extend the technology. For example, in modern times, any child can use a cell phone with a level of expertise. However, beyond the interface, it is a magical black box to them.

The rare inventor, artist or visionary from the past, would come up with something unique from the depths. But after that everyone else walks in the shallows, so the invention gets stuck in time where is decays.

Humans often fall into the trap of thinking the ability to work technology at the shallow interface, means sophistication. Sophistication lies at the depths below the shallows.  A child on a cell phone, looks very advanced and intelligent. However, this is sort of a magic trick. This illusion of sophistication may work in culture, until there is a disruption of service, then everyone sees the wires that allowed the child to appear to levitate and fly.

If there was a disruption of culture, and cells phone were still around, but no longer could be repaired or replaced, the technology gets lost, as the shallow continue to push the buttons, but have no clue how to summons the ancient spirits of the black box.  If there as an earthquake and all the houses were destroyed and all the skilled craftsmen left town, rebuild would look like a homeless town. The shallow sophisticate would haver no clue. They don;t get any dumber but rather the illusion goes away.

A Roman technologist invented the steam engine thousands of years ago. The Romans did not invent it, but rather a person who was Roman invented it. We say the Romans invented it, as though any shallow Roman could do it. This stereotype makes everyone feel more advanced. It is part of the illusion.

The problem in Rome, relative to the steam engine, was the shallow were in charge. They had no vision and saw no use for this invention, which would someday help drive the industrial revolution centuries in the future. The result was the technology was not sustainable, based on the vision of the decision makers, who were not qualified to make that  decisions. In the case of Rome, the decision makers owned the army and can enforce any decision and make it look like the best decision or else.