How many humans have lived on Earth?

[Zdenka]

I call ********. Show us your calcs. I don't come up with a "it's too detailed to put in this forum"

meh, too tired. I've been counting fossils for the last 10 years

 

[Zdenka]

This is a joke.

You do realize that, even in principle, you can't dig up significant numbers of bodies. All but a tiny fraction of dead carcasses are completely destroyed over millennia. Only a very, very,very few are preserved to be later recovered. (BTW, you're not going to find many of them fossilized anyway. Fossilization takes millions of years, not thousands.)

But what about dinosaur bones? I mean human bones should also last a long time too, although they're not as dense of bones of dead beasts.

 

[Jimmy Snyder]

That's one of the reasons why only one-in-a-zillion carcasses are ever fossilized. It's only the ones that are buried in a way where they are protected (tar-pits, river-beds, very fast sedimentation, etc.) from decay due to weathering, bacterial consumption, scavenging and a whole host of other destructive forces.

But what do you call a bone that has been around for a ten thousand years? That's not enough time by your definition to be called a fossil. If it hadn't fossilized wouldn't it have decayed by interal destructive forces?

 

[DaveC426913]

But what about dinosaur bones? I mean human bones should also last a long time too, although they're not as dense of bones of dead beasts.

Did you know that there are only five Tyrannosaur skeletons in existence? 99.999999999...% of ancient skeletons disappear without a trace.

Even if that weren't the case, how do you propose to find all the ones that do exist? Are you planning to scrape the entire Earth's surface to a depth of 100 feet, then sift through those megatons of dust, separating out every human skull you find?

This is ridiculous even for GD.

 

[DaveC426913]

But what do you call a bone that has been around for a ten thousand years? That's not enough time by your definition to be called a fossil. If it hadn't fossilized wouldn't it have decayed by interal destructive forces?

My definition? No. Fossilized bones are bones whose volume in the rock has been replaced by minerals. They are rock.

And yes almost all bones decay by internal and external destructive forces. Which is why Zdenka's idea is ridiculous.

 

[Jimmy Snyder]

My definition? No. Fossilized bones are bones whose volume in the rock has been replaced by minerals. They are rock.

And yes almost all bones decay by internal and external destructive forces. Which is why Zdenka's idea is ridiculous.

So just after death they are bone and millions of years later they are rock. I'm asking what are they in between. If still bone, how do they survive the internal destructive forces to become rock. If rock, why aren't they fossils?

 

[DaveC426913]

Zdenka, come clean with us. Is this a brain teaser that you made up yourself that sounds plausible based on your own understanding of the fossil record?

Because unless there's something you're not telling us, this is just way off the reservation.

 

[DaveC426913]

So just after death they are bone and millions of years later they are rock. I'm asking what are they in between. If still bone, how to they survive the internal destructive forces to become rock. If rock, why aren't they fossils?

You're asking me to teach a basic lesson in paleontology, and I'm no paleontologist, but...

In very rare circumstances, carcasses are buried in ways that prevent decay of the hard structures. Flesh decays quite rapidly of course. Bones, less so, they're a network of calcium afterall; bacteria don't really dissolve them. Decay can be prevented in environments low in oxygen or very cold. If a large animal sinks to the bottom of a very cold lake, or into a tarpit, then its bones will survive long enough for the surrounding sediment to turn to rock. Then, over millions of years, minerals dissolved in water seep through the cracks, dissolve the soft bony materials and carry them away. The cavity left behind can get deposited with new minerals. Eventually you've got a fossil in the shape of the original set of bones but made of rock.

Note that all of this requires that the bones are not disturbed or destroyed by weathering, quakes, or other forces over the entire length of the fossilization process.

You can see that we're very lucky that there are any fossils at all.

 

[Evo]

A: All of them. Now, where's my prize? I want to retire.

Actually, this is the correct answer. I am not aware of any humans that meet the OP's criteria that have not lived and died on earth.

Asking for a specific "number" is not possible, since as it has been pointed out we don't even know of civilisations that might have lived and been eradicated without any record, and since they were wiped out, they have no present day decedants.

 

[Jimmy Snyder]

You're asking me to teach a basic lesson in paleontology, and I'm no paleontologist, but...

In very rare circumstances, carcasses are buried in ways that prevent decay of the hard structures. Flesh decays quite rapidly of course. Bones, less so, they're a network of calcium afterall; bacteria don't really dissolve them. Decay can be prevented in environments low in oxygen or very cold. If a large animal sinks to the bottom of a very cold lake, or into a tarpit, then its bones will survive long enough for the surrounding sediment to turn to rock. Then, over millions of years, minerals dissolved in water seep through the cracks, dissolve the soft bony materials and carry them away. The cavity left behind can get deposited with new minerals. Eventually you've got a fossil in the shape of the original set of bones but made of rock.
.

I'm sorry Dave, but a casual glance at a piece of petrified wood is enough to see that this is not the process.

 

[mgb_phys]

But what do you call a bone that has been around for a ten thousand years? That's not enough time by your definition to be called a fossil. If it hadn't fossilized wouldn't it have decayed by interal destructive forces?

Bone is a bit of a special case. If you remove the organic material you are left with a mineral (calcium phosphate / calcium carbonate) that is pretty stable. Assuming it is buried in a non-acidic dry ground it can last an awfully long time as bone without becoming a fossil.
A lot of remains found in caves and tar pits are not strictly fossils because the bone has not been replaced by minerals - it is the same chemical bone that was in the living animal.

Ironically the incredibly well preserved bodies from peat bogs that preserve the skin and hair contain no bone which is dissolved by the acid very quickly.

 

[Jimmy Snyder]

Bone is a bit of a special case. If you remove the organic material you are left with a mineral (calcium phosphate / calcium carbonate) that is pretty stable. Assuming it is buried in a non-acidic dry ground it can last an awfully long time as bone without becoming a fossil.

But then how does the bone become mineralized? It seems to require water and once water is supplied over a period of millions of years so that minerals can replace the calcium phosphate, where is the necessary non-acidic dry? I think that even if it takes millions of years for bone to become mineralized, something else must happen quite rapidly to stabilize the bone. Whatever that else turns out to be, it should be suffient to make the bone last millions of years even without mineralization. In other words, fossilization should take place within decades, even if mineralization takes millions of years. By the way, why should it take so long to mineralize? I wonder if there is a non-sequitur going on. Many fossils are millions of years old so they must have taken millions of years to form.

 

[mgb_phys]

The classical model of fossilization (you should really call it mineralization - fossilization is used loosely for any old preserved remains) :
Organic matter (the meat on the bones) is destroyed and the remains are buried.
Fine clay/silt etc covers the bones and permeates into all the cavites where the cells once were. You can have negative fossils where the process stops here and you have a mould of the animal body part - this is especially common for plants.
Or with the right conditions you can then have water laden with minerals permeate through the clay and dissolve the original bone replacing it with deposited minerals.
This gives you a classic fossil where the bone is replaced by an exact replica in rock.

The time this takes depends on the geological conditions, there are places with very heavy mineral loaded water where you can coat an object in limestone in a few years. Some are among the first tourist attractions (Petrifying wells) where you could hang up a soft object in the dripping water and it gets coated by rock.

 

[Jimmy Snyder]

Thanks mgb_phys.

 

[DaveC426913]

The classical model of fossilization (you should really call it mineralization - fossilization is used loosely for any old preserved remains) :
Organic matter (the meat on the bones) is destroyed and the remains are buried.
Fine clay/silt etc covers the bones and permeates into all the cavites where the cells once were. You can have negative fossils where the process stops here and you have a mould of the animal body part - this is especially common for plants.
Or with the right conditions you can then have water laden with minerals permeate through the clay and dissolve the original bone replacing it with deposited minerals.
This gives you a classic fossil where the bone is replaced by an exact replica in rock.

The time this takes depends on the geological conditions, there are places with very heavy mineral loaded water where you can coat an object in limestone in a few years. Some are among the first tourist attractions (Petrifying wells) where you could hang up a soft object in the dripping water and it gets coated by rock.

Of course, this is all just rationalization. God did all this 6000 years ago...

 

[Jimmy Snyder]

I wonder if there is a non-sequitur going on. Many fossils are millions of years old so they must have taken millions of years to form.

Of course, this is all just rationalization. God did all this 6000 years ago...

Bingo!

 

[mgb_phys]

Of course, this is all just rationalization. God did all this 6000 years ago...

When scientific measurements, such as radiocarbon dating, are made, the Flying Spaghetti Monster "is there changing the results with His Noodly Appendage.

 

[Jimmy Snyder]

Here is a report from the Smithsonian/NASA Astrophysics Data System

This study evaluates the accuracy of U/Th dates for young (< a few thousand years old) reef corals, both living and fossil, and explores strategies for refining those dates.

Apparently it does not take millions of years to create a fossil. Dryness isn't necessary either it seems.

 

[DaveC426913]

Here is a report from the Smitsonian/NASA Astrophysics Data System



Apparently it does not take millions of years to create a fossil.

I don;t think that's quite the same thing. Corals are already a framework of mineralized organic material.

 

[mgb_phys]

Apparently it does not take millions of years to create a fossil. Dryness isn't necessary either it seems.

Fossil just means 'preserved remains' (it's latin for dug-up) - the bones-turned-to-rock process is properly called mineralisation.

 

[DaveC426913]

Fossil just means 'preserved remains' (it's latin for dug-up) - the bones-turned-to-rock process is properly called mineralisation.

Yes, that was going to be my other comment. When they're talking about corals, I really doubt they're using 'fossil' in the common sense anyway (even if it did mean bones-to-rock).

 

[Jimmy Snyder]

I don;t think that's quite the same thing. Corals are already a framework of mineralized organic material.

Are you saying that the corals were already millions of years old before they died less than 1000 years ago? You have a tenacious hold on this idea that it requires millions of years to create a fossil and that is why I am convinced you can post a citation in support of that idea.

 

[DaveC426913]

Are you saying that the corals were already millions of years old before they died less than 1000 years ago?

What? I never said anything of the sort. They don't need to be millions of years old to be formed of a mineralized framework. They build this while they're alive.

Actually, they build on top of the framework. The living parts of coral are the top few inches formed over a calcified framework of older coral that's been built up over tens of thousands of years. But that's not fossilisation, that's just a calcified remnant structure. Sea cucumbers and sand dollars do a similar thing (just not in giant communal structures). It's basically their skeleton left behind.

 

[Jimmy Snyder]

What? I never said anything of the sort.

If the coral are not millions of years old then fossils don't take millions of years to form. Cite if you will. If not, then your methods are no different than those of a creationist. You believe and so it is true.

 

[DaveC426913]

If the coral are not millions of years old then fossils don't take millions of years to form. Cite if you will. If not, then your methods are no different than those of a creationist. You believe and so it is true.

Jimmy, are you having me on?

 

[DaveC426913]

if the coral are not millions of years old then fossils don't take millions of years to form.

The corals are not fossils.

 

[DaveC426913]

Look.

Dinosaurs and other animals have bones that get buried in sediment. Eventually, the bone is replaced with mineral. We are left with an impression of the bone (not the actual bone). This process of mineralisation takes a long time - eons. It is a non-living, chemical-only process. This is what has traditionally been called a "fossil".

Coral, on the other hand, as a part of the its normal life cycle, secretes stuff that forms a calciferous firmament. As generation after generation of coral polyp lives and dies, this framework builds up to a hgue mound. This takes hundreds to thousands of years and is a part fo the corals' life-cycle.

The two are not the same thing.

What I am claming is that they are using the term 'fossil' in the sense that mgb_phys has stated - i.e. it is merely something they've dug up (the buried ancient coral structures). It isn't "mineralized" and isn't millions of years old; it's thousands of years old.

 

[DaveC426913]

I am wracking my brains here trying to figure out what your beef is. I'm clutching at straws here so I hope I don't insult you when I ask:


You do know that this:

Of course, this is all just rationalization. God did all this 6000 years ago...

was a joke, right?

 

[Jimmy Snyder]

I am wracking my brains here trying to figure out what your beef is.

My beef is that I don't believe that it requires millions of years to mineralize a fossil. I provided a website that speaks of coral fossils that are less than 1000 years old. It is a Smithsonian/Nasa collaboration, not some crank site. If you think the coral was not millions of years old when it died, then fossilazation did not take millions of years no matter how you slice it. If, on the other hand you think the coral was millions of years old when it died and became fossilized less than 1000 years ago, then what makes you think so. I am willing to change my mind on this. But you have provided me with no reason to do so other than asking me to bow to your authority. Cite something. I repeat, you are very sure that you are right. There must be some reason that you are so sure. I am not sure of anything and that is why I beg you to help me out here. It seems to me that something must surely stabilize the remains of a living thing before millions of years pass.

 

[DaveC426913]

Jimmy, this is a misunderstanding of semantics.

I'll say it again, what they're calling "fossils" are not "bones that have been mineralized". What they're calling "fossils" are dead coral mounds that they've excavated.

As mgb points out, fossil can simply mean "stuff dug up".

Look up the lifecycle of coral polyps and the creation coral reefs to understand what I'm saying because I don't think you know what they are.

Perhaps a little bit of the onus should fall on you. You've practically demanded an education in paleontology, and I think I've been pretty accommodating. I'm not asking you to bow to my authority, I'm asking you to look up "fossil" and creation of "coral reef" and see how different they are.

 

[DaveC426913]

Perhaps it would be better to go full over to mgb's definitions and say "it takes millions of years to mineralize buried bones".

Since fossils are merely "dug up stuff" then you could say it takes a very short time for something to "become a fossil" (i.e. just long enough to bury it) - even if it would take eons to "mineralize" it.

Does that make it more palatable?

 

[Zdenka]

Okay, stop arguing guys! I always thought that fossils were dinosaur bones, how else would we get our oil from other than from bones of dead beasts that died long ago.

 

[turbo]

Okay, stop arguing guys! I always thought that fossils were dinosaur bones, how else would we get our oil from other than from bones of dead beasts that died long ago.

From cars that gave up their oil so that other ICE's might live?

When I was running junkers in the 60's and 70's, I sometimes bought Fox reprocessed motor oil in gallon tins. OK, I needed to get to work and couldn't afford ring-jobs, etc. I run some pretty clean rigs, now.

 

[Jimmy Snyder]

I'm asking you to look up "fossil" and creation of "coral reef" and see how different they are.

I have been looking up fossil for hours over the past two days and I can't find a site that says how long it takes to form a fossil. For the third time, what makes you so sure when I am so perplexed? There is no onus on me to show why I'm not sure, the onus is on you to show why you are.

 

[DaveC426913]

I have been looking up fossil for hours over the past two days and I can't find a site that says how long it takes to form a fossil. For the third time, what makes you so sure when I am so perplexed? There is no onus on me to show why I'm not sure, the onus is on you to show why you are.

OK, I think we've been crossing our wires.

I've been perplexed because you seem to have been confusing normal coral reef building with (what I am now finding is technically known as) permineralization. That seems to have been missing the point from my PoV.

(I will frorm this point on, use the terms fossil and permineralisation as per mgb's suggestion. Fossils are things dug up. Permineralization is what happens when bones are replaced with minerals.)

However, I must concede, I do not actually know how long it takes for buried bones to be replaced by mineral. You are right, it is always something I've "just known" and, in this case I have been oversimplifying the issue because this discussion is really (supposed to have been) about humans. And fossilization or permineralisation is just not applicable.

I too cannot find a reference that states how long this process of permineralization takes.