If they were as advanced as we are now, we would have seen that the atmospheric CO2 levels had been higher back then, no? This paper draws the conclusions that such a civilization would be visible in the geological record.
In 1800, there were 1B humans, 1950 is 2.5, 1990 is 5.0B, and we are now at 8.0B.
I think we forget how many more people there are now compared to just 100 years ago. At -5000, there is an estimated 5M people. There's more than 1000x more people now. Per capita carbon footprint would be quite wild to leave any kind of mark on the planet with a total human population that is smaller than a single modern day mid sized city.
Of course, there would also be other markers. Fertilizers is one.
Another is the plants and animals they used for food. Why are some plants and animals still indigenous to certain areas, assuming there was a small globe spanning civilization at some point in the last million or so years? Shouldn't this civilization have at least brought the crops and livestock to other areas of the globe they visited?
Keep in mind that the start of the industrial revolution predates the mass adoption of the steam engine, and charcoal (a renewable resource) based steel mills existed into the 20th century.
I can imagine a world where electricity and batteries were developed before the mass exploitation of fossil fuels as, afaik, there's no specific technological requirement on one for the other to exist.
> Keep in mind that the start of the industrial revolution predates the mass adoption of the steam engine
Well of course the start of it predated the mass adoption of steam engines, but as I understand it the start is generally considered to be when steam engines were first put to use pumping water out of coal mines, that water then being used to flood canals to transport the coal. That synergy was incredibly powerful, making cheap coal available in cities which allowed urban populations to rapidly grow, providing a workforce for the factories which would eventually (not initially) also be coal powered. That's the industrial revolution as I learned it.
So what you're saying is there was a massive technologically advanced civilisation which didn't build buildings, didn't carve stone, didn't mine or refine metals, didn't deforest, didn't farm, and didn't use oil?
> Terra preta soils are found mainly in the Brazilian Amazon, where Sombroek et al. estimate that they cover at least 0.1–0.3%, or 6,300 to 18,900 square kilometres (2,400 to 7,300 sq mi) of low forested Amazonia; but others estimate this surface at 10.0% or more (twice the area of Great Britain).
It could be that the technological civilization arose extremely quickly, and only in certain limited geographical areas before the population could grow to overwhelm the earth with industrial production. They might have had a completely different morality that led to this pattern. It was before the founding of all religions we have today.
Maybe, but I doubt that as technology seems needs a lot of specialists. You don't have time to focus on one small area in depth if you also need to farm/hunt/gather. We need generations for someone to come up with the idea of writing, make it better, educate kids in it... And of course before the printing press books took a lot of time and so even if you created something passing it to someone else is hard.
Primitive people were not stupid, they just needed a lot of time to figure out things that we now think are obvious.
I think you under emphasized the first part of your point. Living in a modern community is easy mode. Without that, mass time and effort are needed to subsist
https://arxiv.org/abs/1804.03748