Yeah, these are sophisticated constructions; referring to them as just “mounds” belies the effort and logistical coordination necessary to build such structures, and the complex and sophisticated societies that their existence represents. But they aren’t multi-chambered temples with sarcophagi and elaborate tools, and for the most part North Americans had only copper and stone tools, not having ready access to tin and iron deposits or the means to smelt and alloy them into bronze and iron.
There are gaps in the fossil record. The further back you go in time, the longer the gaps. Humans have had technology for maybe 6000 years. With our current fossil record of the Cretaceous, I don’t think we have that kind of precision.
Human technology goes back much further than 6000 years; the Neolithic “founder crops” have been cultivated for at least twelve millennia, and evidence of husbandry of pigs and sheep even slightly further back. Of course, humans and their predecessors have been using ‘technology’ in the form of fire for over a million years, and there is evidence of the manufacture and use of stone tools by Australopithecus afarensis more than 3.3 million years ago.
We have enough of a fossil record to observe with near certainty that no species (plural) during the pre-Cenozoic period emerged with anything like the grasping appendages needed for complex tool use and manufacture. Such a development should have left a long lineage of evolutionary development and, if they had expanded to the extent of even the Late Antiquity, that is still a couple hundred million bodies which should have left something in the fossil record, if not their own fossils then evidence of hunting or wide scale agriculture over a period of at least tens if not hundreds of thousands of years of development and expansion.
Ref the comments by @Stranger_On_A_Train & @MrDibble about artifacts surely being left over from a prior civilization were any ever created. …
Totally agree, at least for still-extant crust. But …
What is the timeline to completely resurface Earth and subduct 100% of the extant crust under the mantle? I know I do not know.
I think it’s a reasonable assumption that except for long-lived unnatural isotopes, no civilization of our tech or even higher is going to leave artifacts that survive processing through the mantle to later emerge in fresh crust. It’s only artifacts from more recently than that which can still exist to be found.
Perhaps Earth is not yet old enough to have had life from before any of the current crust existed. But I propose that if humanity simply dropped dead tomorrow, all our current artifacts, both ancient pyramids and modern iPhones, will eventually subduct. A hypothetical future intelligent species, regardless of their biological nature, that arises after our era’s crust’s subduction was complete would never find evidence we’d ever been here. Or at least that’s my SWAG.
Let’s put it this way. There can be exactly as much proof of the existence of such artifacts as there is evidence for the proof of a god, and the discussions of either must be founded in belief rather than science.
There is bedrock in Canada that is 4.38 billion years (Byr) old, and geological features in Australia that are nearly that old. Uluru (Ayers Rock) is actually comparatively youthful at ~500 Myr. Most of the Earth’s surface isn’t so much subducted as it is worn away by weathering (denudation), overlain by volcanic flows, and periodically covered by oceans (marine transgression) that deposit silt and sand that is compressed to new layers of rock as well as coral accumulation. A professional geologist or geoscientist could give you a deeper explanation but essentially everything you see is on the surface is a combination of old and new, often mixed through tectonic uplift, subsidence, et cetera.
It is generally accepted that multicellular life didn’t move onto land until the Cambrian Explosion circa 540 Mya and vertebrate terrestrialization didn’t occur until around 375 Mya. We have a good enough fossil record as well as lithographic strata to be confident that no land vertebrate would have been capable of developing any kind of world-spanning society or industrial production in that time or after and leaving no trace. Marine life—particularly cephalopods—are more difficult just because the fossil record and kind of technologies they could conceivably develop would almost certainly leave fewer residues, but again there is nothing in evolutionary history that would suggest that squid, octopuses, or other animals were capable of building an industrial society.
It is an interesting topic to ponder because it does offer novel insights into what kind of intelligent life could evolve on different worlds or the watery moons of gas giants, but it is implausible to the point of near certainty that an previous industrial society ever emerged on our planet.
I don’t know what it is either. But the current theory about the moon is that it was formed when something roughly the size of Mars slammed into the Earth around 4.5 billion years ago. Parts of Australia contain crust that dates to around 4.4 billion years ago, so pretty close to that.
I think it’s fair to say that the Earth had a really bad day when the moon was formed and that we’re probably not going to find too much evidence for what was on the surface before then. But then there probably wasn’t much in the way of life considering that the Earth itself only formed around 4.6 billion years ago. There wasn’t time for much of anything to develop before there was literally an Earth-shattering kaboom.
In the 4.4 billion years since, the Earth still hasn’t completely resurfaced, so it’s longer than that.
So if you want all traces of these prehistoric civs to have been subducted, you’re back to oceanic life. And not just any ocean life, but exclusively deep-water ocean life, because we have plenty of shallow-water ocean sediments preserved. That’s just fantasy-land again, IMO. Not enough motivation for civilization to develop in the deep but not the shallows.
While almost certainly impossible for reasons already given, there’s a scifi novel Toolmaker Koan by John McLoughlin that posits intelligent dinosaurs that instigated a global civilization-destroying war (I think nuclear, but it’s decades since I read it) 65M years ago. Used iridium for lots of things, hence the showering of it everywhere in the fallout. The googling about required to identify the book turned up some reviews that pan it. My hazy recollection of reading it was being delighted in the premise, but I have no recollection of whether it was any good beyond having a delightful premise.
That’s ridiculous for soooo many reasons. Iridium is rare as fuck in Earth’s crust (it’s the absolute rarest) and always was since at least the Earth cooled, and no civilization is going to get to the point of using iridium and not also using a whole lot of other metals that would have left even larger traces in that layer.
Well, the book is a moralistic tale about how (supposedly) intelligent toolmakers inevitably blow themselves up, and there may well have been any number of scientific ridiculousnesses. As I said, I read it decades ago and recall little beyond the basic premise.
Define “technology”. Ancient humans had quite a wide range of technology. The Antikythera mechanism proves that.
Back to the OP- yes, there is still quite a lot of discover. Many, many building, monuments, graves, whole cites and even maybe unknown civilizations.
Yes, mostly, although there were traps, but those generally can’t stand the march of centuries.
Rumor is that the tomb of Qin Shi Huang was/is trapped, but it seems to be too dangerous to open due to huge amounts of mercury. That is about the closest.
Well, yes. Or more like “Absence of evidence where such evidence is to be expected, is evidence of absence”
If you’re trying to advocate that absence of evidence is not evidence of absence, well, that’s a nice homily, but it’s bunk. It’s trying to equate my above expanded formulation with argumentum ad ignorantiam when it misses a key part of what makes that argument a fallacy : the ignorance argument only applies if there may have been an insufficient investigation to prove that the proposition is either true or false. In the case of prehistoric civilizations, there has been sufficient investigation <points dramatically to all of geology and palaeontology>
Thanks experts! I knew we had some ancient pre-life crust still laying around accessibly now, but not how much. As I hope I’d said clearly enough, I was less thinking of us finding old artifacts of ancient them vs. some future them finding (or not) old artifacts of us.
Now that I more fully understand continental crustal dynamics, that ain’t gonna happen either vs the remaining ~500My lifetime of conventional life on Earth vs the Sun’s increasing luminosity.*
Seems like it’s one and done for much of our crust. So most any life (and especially technological life) will leave a record for longer than there’s anyone / anything on Earth able to look, much less find. ETs excepted.
Another fact-bite from that cite is that following a planetary mass extinction event where the subsequent geo-setup is still decently hospitable to life in general, the prior biodiversity should return in ~10M years. Certainly not the same actual species, but just the overall level of biodiversity. There’s probably a lot of handwaving and ceteris parabus in how that figure was derived, but I’ll run with it here unquestioned.
If valid, that suggests the planet could radically turn over its biosphere up to about 50 more cycles if mass extinctions occurred often enough and Mother Nature keeps re-rolling the dice from bio near-ab initio. The actual past history of mass extinction events suggests a few more such events would be closer to par for the course.
It seems that Göbekli Tepe has not been mentioned yet.
It shows that unexpected findings are to be expected if somebody who knows what they are doing keep their eyes and their minds open.
First noted in a survey in 1963, the importance of the site was recognised by Schmidt, who directed excavations there from 1995 until his death in 2014. Since then, work has continued under the auspices of Istanbul University, Şanlıurfa Museum, and the German Archaeological Institute, under the overall direction of Turkish prehistorian Necmi Karul. It was designated a UNESCO World Heritage Site in 2018, recognising its outstanding universal value as “one of the first manifestations of human-made monumental architecture”. As of 2021, less than 5% of the site has been excavated.
There is another site close to Göbekli Tepe, Karahan Tepe, perhaps 500 years younger, about which even less is known because the discovery is even more recent.
I would like to visit both before the Islamic State or somebody like them destroys it.
Unfortunately anything related to Erich von Däniken is false.
The Chavin culture is another exame of monumental architecture that was vaugely known about for decades but the extent of it was not really understood:
Laser-Dinosaurs aside, the world is still certainly still full of remains of unknown or little known civilizations and cultural groups, many of which are probably on the scale of Machu Picchu. For one thing, we’ve spent the last 100 years only looking in places and times where we know there was significant agriculture. It’s becoming obviois that’s a faulty assumption.
Eta: I actually meant Caral, not Chavin, but both have the same basic story: somewhat known, but the scope was not understood:
On the pre-human technology side topic, I’ll throw in that beside appendages suitable for tools missing, you also have the following issues:
Tiny brains. We haven’t - to my knowledge - found any ancient skeletons that had room for a brain large enough to develop and use advanced tools.
The ability to speak and learn through conversation amounts to a massive leap over evolution. An intelligent species can adapt to new situations within their own lifespan, where most species need to slowly migrate from one environment to another through sexual success over many generations. So if we’re talking about extinction level events and some creatures surviving through that, and others not, the intelligent species is the least likely to perish. They’ll actually see and understand what’s happening and devise means of adapting. And that’s especially so if they’re at the level of using advanced tools already. Similar to the phrase “life finds a way”, I think we can be certain that “intelligence finds a way” would also be true. Of any species that would survive through to modern day, the intelligent species would be the most likely to persist.
Similarly to the previous, an intelligent species can be expected to massively dominate and kick the asses of non-intelligent species. The rise of humanity, for example, is correlated with the end of most species larger than humans - across the entire globe. We would expect any previous intelligent species to have done something similar, and we don’t see that.
Now, granted, 2 and 3 could be tied together to create a theory that the great dinosaur extinction could have been evidence of the rise of an intelligent species. But, again, if our hypothetical intelligent species is the cause of the extinction event then they’re not the ones going extinct. They would be the last ones going extinct - eating all the chickens that they allowed to survive the large dinosaur purge - and they would persist through the millions and billions of years through to the rise of humanity.
This brings us to two further points:
They would either have prevented our rise - seeing us as a threat - developed us into an equivalent of dogs - forcibly capped out at a certain level of intelligence - or partnered with us. Only in that third scenario do we get to where we are today and, in that case, they’d still be here.
The amount of dominance over the planet and the duration of dominance would both have ensured that they’d be preserved in the fossil record.
Annalee Newitz recently brought out Four Lost Cities: A Secret History of the Urban Age. The four cities are Pompei, Angkor, Cahokia and Catalhoyuk. She visits each one and talks to archaeologists on site who have devoted lifetimes to the research. One point she makes repeatedly is how much new stuff gets found long after the initial discovery, some of it massive. In 2015, a team found a whole complex at Angkor much bigger than the famous temple there.
The book is short and very accessible. I’m not a big fan of first person what I saw books but that’s all the rage these days so I assume others will find it irresistible.
