Would there be any way of knowing if dinosaurs had a civilization?
September 7, 2014 2:36 PM   Subscribe

How would we know if dinosaurs (or some other species) achieved sentience and civilization millions of years ago? 65 million years is a long time, would a civilization with a, say, 10,000 lifespan even be noticeable in the geologic record? What if they only reached 19th century technology and didn't use nuclear power or plastic?
posted by blahblahblah to Grab Bag (17 answers total) 18 users marked this as a favorite
If there was a widespread technological civilization, we would know it because we would see the results of their mining. Places where our geology science said there should be ore, wouldn't have, or not as much. We'd also be able to find places where they had dumped their mining spoil, because it wouldn't make any sense geologically (no layers, no fossils, not aligned with the planet's magnetic field, etc.)

Likewise, we would find their garbage dumps. Artifacts wouldn't survive that long, but there would be a mix of metals in the soil that made no sense geologically: iron ore, aluminum ore, cadmium ore, tungsten ore, nickel ore, all mixed together in ways which can't happen naturally.
posted by Chocolate Pickle at 2:43 PM on September 7, 2014 [6 favorites]

Not to threadsit, but would the thin geological layer of a garbage dump really be easy to detect after 65 Million years? I thought about that and about mines, but wouldn't they collapse and be distributed quite quickly in geologic time?
posted by blahblahblah at 2:52 PM on September 7, 2014 [1 favorite]

Well, plastic is durable, but it's not the only sign we have to see evidence for "civilization". Stone tools (and flakes), signs of intentional tool use, evidence for structures, worked objects, art-- we use these to understand human history and the evolution from human ancestors from hundreds of thousands of years ago. Paleontologists know a lot about dinosaurs and their environment: there's evidence for certain species for nesting and herd behavior, for example, and copious amounts of information about what most dinosaurs ate, where they lived, surrounding flora, atmospheric components, and so on. There is no evidence for even basic tool use in dinosaurs, as far as I know. Someone else probably has better data on dinosaur brain structure and what that means in terms of behavior and intelligence though-- I don't think we can postulate anything about language or communication, though I suspect vocalization was probably limited. "Dinosaurs" also occupied a stretch of the timeline over a hundred million years long, with (thousands?) of species evolving and dying out throughout that time period.
posted by jetlagaddict at 2:54 PM on September 7, 2014 [3 favorites]

I'd have to think that fossils that show impressions of soft tissues in our world, while rare, would show impressions of clothing and similar items in a sentient-dinosaur world, especially if they were leather (which would presumably last at least as long as soft-tissue remains). Not to mention at least impressions and stains of metal tools.
posted by ROU_Xenophobe at 2:59 PM on September 7, 2014

I thought about that and about mines, but wouldn't they collapse and be distributed quite quickly in geologic time?

Presumably no more or less quickly than the layers of rock that contain the fossils of dinosaurs. We know dinosaurs existed because of that evidence, so if they had a civilization we just haven't discovered yet, the evidence of that civilization would have to be less viable than dead dinosaur bodies.
posted by jacquilynne at 3:01 PM on September 7, 2014 [2 favorites]

You might be interested in reading up on the concept of the "Anthropocene," which attempts to imagine how future observers many millennia or millions of years hence might be able to recognize the evidence of human civilization in the geological record. Most of what we'd done would vanish pretty quickly, geologically speaking, but things like the carbon record, atomic radiation, and trash like plastic and glass bottles would last a long time and would be recognizable to future observers. Other theorists of the Anthropocene go further, and point to the mass extinction of megafauna in the Americas as well as Native American forestry practices as something that would be recognizable as the work of intelligent beings to aliens or Cockroach sapiens that didn't already know we'd been here. You'd also likely be able to tell from soil degradation and desertification in the Middle East and Northern Africa that the place had been overfarmed (a process that long predates advanced technology).

There's nothing like that suggesting that dinosaurs had any sort of complex civilization, needless to say, and our understanding of their biology and mental capacity makes it really unlikely that we're somehow missing the evidence.
posted by gerryblog at 3:02 PM on September 7, 2014 [6 favorites]

but would the thin geological layer of a garbage dump really be easy to detect after 65 Million years?

It would be part of the sedimentary record, but such a thin layer would likely be reworked by erosion in some places and preserved in others. Nothing is "easy to detect" but it is impressive what geologists can observe in the rock record. Keep in mind that very thin layers of ash and chemical anomalies associated with the K-T impact event are preserved in the sedimentary record, even though that event represents just a brief moment in time 65 million years ago. So it isn't impossible.
posted by Seymour Zamboni at 3:03 PM on September 7, 2014 [1 favorite]

Arguably, we're not even sure what the ancient Egyptians OE Greeks were capable of...
posted by grateful at 3:10 PM on September 7, 2014 [1 favorite]

To get to 19th century technology, humans had to pass through a LOT of stages, from using existing things as tools, to learning to create tools from stone and other materials, to learning to create fire, to learning to implement it in the landscape and for food, to animal husbandry, to land agriculture, which leads to settled civilization and onward to metallurgy and advanced tools, not to mention the time and sedentary society needed to invent the physics and maths that sent us down the path toward 19th century technology! Which was really advanced!! And many, many, many, many spurts of intellectual and cultural developments, mingling, and resets happened in between stages.

So, with the amount of material resources (and prefrontal cortex) needed to develop even from loosely organized omnivorous foraging animals into an intelligent society, there tends to be a lot of landscape manipulation in the sequence of developing culture.

A prehistorically burnt landscape can be identified in the earth's strata by archaeologists, as can evidence of stone quarrying, middens, clay harvesting, and most definitely evidence of ore mining. Clean, straight lines occur very rarely in nature, so generally anything with an edge, like a quarry cut or blade edge, tend to stand out if not as intentionality, then at least as an unusual form of activity. Mines may collapse, but the straight edges of say, wooden beams used to create a mining structure, or even debris from the process of mining, would have been preserved *somewhere* in dinosaur findspots around the world if it had been happening.

Likewise, the remnants of the earliest Paleolithic humans, usually stone tools, date to at least 2.5 million years old, so these things can and do survive in the archaeological record.

Like Chocolate Pickle said, there would be geological evidence of any advanced society predating our own, even by millions of years. And if there were any doubt, the biological evidence in terms of brain size and even dental record of dinosaurs does not lead anyone to speculate that they had anything approaching what we would call sentient culture.
posted by Queen of Spreadable Fats at 3:31 PM on September 7, 2014 [4 favorites]

If dinosaurs had a civilization, there would likely be evidence of medical or cosmetic practices on their bones. There would also likely be signs of dinosaurs having been cared for (presumably by other dinosaurs, for social reasons) even after traumatic injury that would have compromised mobility. The placement/location and surroundings of the bones would also give us clues as to dinosaur burial practices. The placement/location and surroundings of the nesting areas would give us clues as to social behavior and how the species reared their young. Those are some things we look for on human bones and artifacts to figure out what pre-history societies were like, anyway.

There actually is some evidence that at least some species of dinosaurs were social animals. I'm not sure what you would count as a "civilization," but some of them did have "society," in a sense. For example, some species had communal nesting behavior and cared for their hatchlings after birth (cite).

Birds are descended from dinosaurs, so their social behavior might be more comparable to bird social behavior than it would be to familiar mammalian social behavior. Since dinosaurs are very different animals than us humans, I'm not sure how to compare dinosaur sentience or civilization to ours? I mean, what would count as "sentient" or "civilized" for dinosaurs? (I'm actually asking, if anyone can define those terms better/more clearly in this context?).
posted by rue72 at 4:07 PM on September 7, 2014 [7 favorites]

A few points at opposite ends of the scale of civilisation:

- Lots of human burials involve rituals, such as burying tools, symbols or other humans in a grave with the deceased. I imagine we'd have found some evidence of this already if it occurred with dinosaurs.

- A lack of any refined food in fossilised stomach contents.

- I remember reading somewhere (though I can't find it now) that if humans were to disappear tomorrow, one of the longest lasting signs of us ever having been here would be equipment left on the moon. As there's no atmosphere, water or tectonics, things hang around there until they're buried by dust, with takes a long time. So from the lack of massive landing craft left on the moon, we can assume T-Rex never mastered the moon landing.
posted by Ned G at 4:22 PM on September 7, 2014 [4 favorites]

would the thin geological layer of a garbage dump really be easy to detect after 65 Million years? I thought about that and about mines, but wouldn't they collapse and be distributed quite quickly in geologic time?

I dunno about the dinosaurs, but human garbage dumps ain't "thin" by any calculation. Typically 50-150 meters thick and covering dozens of acres. Then covered with a layer of topsoil once they're full. I've read a factoid that the highest point on the Eastern seaboard is a garbage dump on Staten Island.

In 50 million years, some of our garbage dumps will be gone or seriously covered up, but not all of them.

The issue with mines isn't the presence of tunnels. Those won't last. The issue is all the ore that was removed. Our geology will say that it ought to be there, but it isn't.

Some Roman era mines were detected that way.

The surface of the Earth isn't as plastic as you seem to think. As mentioned above, we have access to many strata which date to the dinosaur era, and many which date much earlier. The Grand Canyon is actually a good example; the rocks at the bottom predate multicellular life.

There is erosion; no doubt about that. But it doesn't happen equally everywhere, and in some places it doesn't happen at all. No, dinosaurian mining activity wouldn't be totally obliterated by geological processes in 65 million years.

Check out this mine. Maybe it gets filled in, in which case the new material in there doesn't match the surrounding strata. Maybe it doesn't get filled in, in which case its existence is difficult to explain through natural processes. There are monstrous open-pit mines like this all over the world. There's one in Brazil located at the spot where there used to be a mountain. The entire mountain was excavated away and they kept digging, because there's gold there.

In 60 million years some of them will be obliterated by geological processes, but not all of them. There are parts of the crust of this planet which have been stable for 2 billion years; 60 million years is an eye-blink as far as that kind of geology is concerned.
posted by Chocolate Pickle at 5:07 PM on September 7, 2014 [3 favorites]

By the way, the petroleum we use was laid down in sediments during the Carboniferous era, 300-350 million years ago. If your hypothetical dinosaur civilization discovered how wonderful a fuel petroleum is, we'd know it because most of the oil we've been bringing up wouldn't be there.

And no, 60 million years of geological activity wouldn't affect this.
posted by Chocolate Pickle at 5:13 PM on September 7, 2014

What exactly defines "civilization"? I'm not sure if we can judge dinosaurs having a civilization, or not, by comparing their remains etc against human standards.
posted by TrinsicWS at 1:22 AM on September 8, 2014 [3 favorites]

Almost everything said here is a good point, but I think people may overestimate the percentage of the Earth's surface from the time of the dinosaurs which is even accessible to humanity, let alone that which has already been excavated.

What percentage of the Earth's surface is occupied by mines, by trash heaps? Way below 1% I think. It is easy to imagine a fast-evolved, geographically limited, dinosaur species developing culture and bronze-age technology and then being wiped out and leaving little or no evidence. Pure speculation, of course, but there's plenty of room for it.

Imagine if humanity had gone extinct in the 1300s AD. What fossil or archaeological evidence would be likely to be found 65 million years later?

I recently read a story by Greg Benford and Larry Niven called Bowl of Heaven, and this idea is a minor element of that story. Except in that book, some of the dinos became space travellers.
posted by General Tonic at 11:28 AM on September 8, 2014

grateful: Arguably, we're not even sure what the ancient Egyptians OE Greeks were capable of...
Actually, we're pretty damn sure they were capable of: making clothing, building buildings, processing food, and writing.

All but the last would be at least as preservable as dinosaur skin, of which we have some.

And even the earliest human civilizations practiced ceremonial burying; AFAIK manufactured implements have never been recovered from the same strata and immediate vicinity of a dinosaur.

So: we can be sure that dinosaurs probably did not have a civilization, and the ancient Egyptians and Greeks did.
posted by IAmBroom at 9:48 AM on September 9, 2014 [1 favorite]

Humans have been conducting the major natural sciences of the past (geology, paleontology, archaeology, etc) for about 200+ years, and doing it systematically for over 100 years. There is close to a zero percent chance that we would have missed another Victorian-like culture or technology at some point in the past.

Lots of people have pointed out upthread some of the evidence that we would have seen. I would emphasize that an early industrial culture produces lots and lots of durable (stone, pottery, metal) objects and would have produced these for millennia to reach an Industrialized society. These would have been found by now. Even given the changing Earth, we have enough access to 65 million year old landforms through natural and cultural means that these would have been discovered. If we can find the fossils we can find the tools. Period. In fact metal, stone, and ceramics are more durable and more likely to survive than bone which must find fairly rare conditions in order to be fossilized.

Most of the major archaeological discoveries of the last decade or two, when we realize that something happened much earlier than we previously suspected, have a common thread. Here I include the discovery of monumental architecture in SW Asia in the form of Gobekli Tepe thousands of years earlier than might have guessed or consensus building around pre-Clovis people in the Americas a few millennia than was "textbook" wisdom a few decades ago. In both cases, the problem facing archaeologists was that the early stuff ends up looking somewhat similar to the later stuff. So it was under our noses all the time, we just didn't understand its significance.

I would assume this would not at all be a problem with dinosaur tools and buildings. The metal, stone, and ceramic objects would be built for and by different bodies and would not at all resemble the later stuff. It would immediately stand out.
posted by Tallguy at 9:37 AM on September 11, 2014

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