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tty
A real weird news story from Nature about meteor damage to pleistocene fossils:

http://www.nature.com/news/2007/071212/ful...s.2007.372.html

If traces of this meteor shower has been found in both Siberia and Alaska as the story implies, then multiple impactors must have been involved. Such small meterites would lose speed quickly so the airburst must have occurred at fairly low altitude.
Rob Pinnegar
Yeah, I read this one the other day. Very peculiar (and, really, more-or-less unbelievable).

It should at least be interesting to see how it develops.
helvick
QUOTE
The discovery of the 25 millimetre holes left by meteorites opens a window into a impact event thought to have happened over Alaska and Russia tens of thousands of years ago.


I can't see how this could be possible.

They are proposing that millimetre/sub-millimetre meteoric debris could have reached the surface at a sufficient velocity to penetrate bone to a depth of a few millimetres and done so over a geographic area thousands of kilometers across. I don't see that being at all likely - such small particles have a very limited range at such velocities (a few km at most) and if the velocity rises too far they will vaporize and any low altitude airburst that is small enough to generate the debris shower without a cataclysmic shock wave that would have totally destroy the tusks could not be large enough to cause similar effects across such a large range.

I would also describe this sort of provenance for evidence as a bit suspect:
QUOTE
West bought the 60-centimetre tusk for about US$200, and later headed to the warehouse of the company that he bought it from: Canada Fossils.

If you ask me it is easier to think that the damage he has detected was caused by someone doing some welding near those tusks at some point in the past rather than micro meteorities peppering mammoths and bison during a prehistoric mega meteor storm.
As old as Voyager
The idea that these animals were present and in the immediate vicinity when a meteorite hit the Earth is interesting. However, I find it quite unlikely.

To me, a much more plausible explanation is that our ancestors were hunting with meteorite material. All they had to do was find an iron meteorite, smash it into sharp shards and attach the shards to wooden poles to form an effective hunting spear.

The meteorite material embedded in the tusks and bones would therefore simply mark the impact point of such a weopan.
helvick
Now that's a much more plausible explanation - good thinking there.
TheChemist
QUOTE (As old as Voyager @ Dec 16 2007, 02:47 PM) *
The meteorite material embedded in the tusks and bones would therefore simply mark the impact point of such a weopan.


From the article : "Some of the tusks are peppered with hundreds of the fragments, which had burnt grooves into the bone. All the pieces entered the bones on the skyward surfaces of the tusks and skull."

The quantity of the fragments, along with the fact that they burned the tusks on their way in suggests spears or arrows are not likely explanations.
Unless prehistoric people made bullets out of meteorite fragments smile.gif

Edit : A lot more information in the poster from AGU.
djellison
There are records of ancient people using meteoritic material in tools etc - they were highly prized as they didn't know how to make their own metal at the time. Makes a LOAD more sense to me. Little fragments wouldn't be travelling at high speed. They'd loose all their energy really quickly. (consider the old penny-from-tall-building myth - which is indeed a myth)

The chance of a fragment small enough to make those marks, travelling fast enough to make those marks, and 'hot' enough to scortch them...sorry - I find that very hard to believe
Doug
nprev
Weird story. The only other alternate explanation might be a Tunguska-style event in which the impactor basically detonated near the ground & spread shrapnel far & wide. However, this is difficult to envision for a typical iron/nickel meteorite; perhaps a cometary body with complex composition (as we've seen hints of in Wild-2 from Stardust?) huh.gif
Rob Pinnegar
Well, here's a thought. Let's assume for the moment that things happened the way the authors suspect they did.

One of the key points here is the geographic distribution of the bones. Keep in mind that we're talking about very small fragments of meteorite here. Thus the animals in question might not have been killed by the impact. They may have subsequently wandered a long distance before eventually dying -- throughout Alaska and over the Beringia bridge into Siberia.

Thus the impact event could have been localized to Alaska.
nprev
I've always wondered about this particular (apparent) astrobleme in Alaska. If it is in fact a hit, it looks pretty fresh; still has a semicircular aspect, and Alaska is nothing if not geologically active...ask me how many quakes I felt when I lived there, 2001-2004... rolleyes.gif
dvandorn
You know, any really energetic impact will create secondary projectiles. I can imagine that there would be a "ring" around an impact site where the ejecta would still be red-hot when it landed. That ring could be pretty large, depending on the size of the impact, the characteristics of the target, etc.

Besides, I would think that something coming in at cosmic velocities would shatter a horn or a bone, not burn a hole into it. I don't think the described damage necessarily requires that the objects which hit these beasts to have had the speed of a primary impactor.

-the other Doug
tty
More details here:

http://news.bbc.co.uk/2/hi/science/nature/7130014.stm

It looks as if there might really be something in it. If it happened 30,000 years ago, then humans are out - there weren't any in Alaska at that time, and if there are signs of bone growth afterwards then it obviously happened while the animals were still alive.
nprev
Huh. That's pretty damn scary, really. What could cause a metallic body to apparently, literally explode to the degree needed to generate small high-speed fragments like this? All I can think of is a VERY high impact velocity that basically melts the thing in a few milliseconds, but that sounds screwy to me, too... huh.gif

My previous Tunguska-style scenario doesn't sound plausible, either. I don't see why any chunks of iron-nickel wouldn't survive the explosion of the volatiles more or less intact instead of shattered into shrapnel.

There's a big piece of this puzzle missing. A lot's going to depend on the actual age of the fossils. If it's later then the colonization of North America, then I'd definitely favor the spearhead theory (IIRC, 30Kyears is still just barely within the realm of possibility for human migration to the Americas).
tty
Here is a link to the actual AGU poster:

http://ie.lbl.gov/mammoth/AGUSF_poster_2.gif
tasp
{sorry, did not pay to read entire article, if this has been ruled out . . . whatever}

Any chance we are seeing the effects of a lightning strike in proximity to the mammoth, and perhaps a rocky outcropping of an appropriate ore ??

Even an unlikely lightning effect seems, on first glance, similarly probable to an (unprecedented?) meteoritic phenomena.
nprev
Problem is that the metallic residue does match meteoritic compositions (including Ir enrichment), from what I read. Plus, it seems as if the event may have affected a fairly large geographical area, the possibility of animals being not too injured afterward (also mentioned in the article) to still wander far & wide notwithstanding.

Hmm. Maybe the shrapnel particles don't have to be traveling too fast...maybe they just need to be very, very hot to penetrate the skin & bones (yuck, I know--wouldn't feel good at all for the poor critters). Whatever would blow a metallic meteorite into smithereens like this, you can bet that the smithereens are gonna be pretty warm for awhile. I'm betting on a large iron/nickel body with an unusually high impact velocity, say several tens of km/sec, that maybe took a shallow chord through the atmosphere that allowed it to heat up enough to blow up...
djellison
But surely a meteorite fragment that small would cool in the 'flight' phase?

Doug
tasp
OK, read some more on this, and will gladly back off the lightning idea.

However, do these 'tiny bits' have sufficient range in the earth's atmosphere to pepper mammoths, but whatever accelerated them is insufficiently energetic to kill the mammoth??

I am having trouble seeing the mammoth in the 'sweet spot' of the calamity for it to wind up this way. Terminal velocity of these tiny bits in air isn't all that high (watch Mythbusters) and whatever is accelerating them is 'worse' than they are, isn't it ?

{everyone loves a mystery, don't they!}



Just out of curiosity, have any soft minerals on Mars examined by the microscopic imager have any features that might be interpreted as produced in a similar event ?? For instance, if a sulfate rock (if that would be comparable in hardness to tusk) has little pits on the upper surface in the size range noted in the article, whatever is doing this in Alaska might be generally operative on Mars??
nprev
QUOTE (djellison @ Dec 18 2007, 07:30 AM) *
But surely a meteorite fragment that small would cool in the 'flight' phase?

Doug


Not sure; lots of variables. Metal doesn't cool very rapidly in air anyhow, and if the frags aren't really traveling that fast then they'll cool even less. Grenade fragments are hot as hell for several minutes after detonation, for example...

Tasp, it also appears that these things (whatever they are) didn't necessarily kill all the animals that they hit. Some of the bones showed signs of long-term healing.
helvick
QUOTE (nprev @ Dec 18 2007, 03:40 PM) *
... Metal doesn't cool very rapidly in air anyhow, and if the frags aren't really traveling that fast then they'll cool even less. Grenade fragments are hot as hell for several minutes after detonation, for example...

Yes but grenade fragments travel a few tens of meters at most - if they were to travel through hundreds or thousands of meters of air they would cool rapidly.

I'd like to see someone work out a viable model that creates thousands\millions of small high velocity (or high temperature) fragments at ground level from a meteor entering the atmosphere _without_ noticable blast effects. I'm going to see what I can get from just running velocity\drag\density and range numbers.
nprev
Yeah, I was thinking about what sort of model would work as well. The "shrapnel" hypothesis is thin as paper; if it can work at all, looks like it needs all sorts of very special circumstances. Still, can't think of anything better.
lyford
QUOTE (nprev @ Dec 18 2007, 04:42 PM) *
Still, can't think of anything better.

Cro Magnon Blunderbuss? unsure.gif
nprev
At this point, I'd almost rate that just as likely as magic exploding metal meteoroids... tongue.gif ...this is a weird one for sure.
AndyG
QUOTE (lyford @ Dec 19 2007, 12:58 AM) *
Cro Magnon Blunderbuss? unsure.gif


A flintlock, for certain.

Andy
ngunn
Can't help noticing the resemblance between this shower of missiles and Don Burt's impact-generated condensation spherules. Any comment on this story dburt?
algorimancer
I wonder whether this may have more to do with the mammoth using their tusks to dig in the ground (as I seem to recall that modern elephants do) and in the process embedding the metal fragments from a meteorite which just happened to be buried in the soil. In this case the "burn marks" may simply be oxidation rings and/or due to inflammation around the embedded fragments. This may also correlate with the dorsal distribution of the fragments - I would envision the mammoth pushing the tusks into the ground, then lifting. The same explanation works for the bison horns. I'm having a really tough time accepting them as due to the impact event, as any event which yields small particles moving fast enough to do this would likely also be throwing out a lot of big rocks and heat, and the bigger rocks would travel further than the small particles.
ngunn
QUOTE (algorimancer @ Dec 19 2007, 02:45 PM) *
the bigger rocks would travel further than the small particles.


Maybe not if they are fallout from a mushroom cloud.
algorimancer
QUOTE (ngunn @ Dec 19 2007, 09:34 AM) *
Maybe not if they are fallout from a mushroom cloud.

And my assumption was that all the particle sizes would have begun with the same velocity, and thus the smaller particles would be decelerated by the air faster than the larger ones. The opposite is also true, that the smaller particles would be accelerated more than the larger particles by an expanding volume of gas.

I could believe the impact hypothesis more easily in the context of your notion of fallout from a mushroom cloud (or secondary impact) if I could be persuaded that the terminal velocity of particles of this size would be sufficient to embed them within the tusks. This falls under the old "if you drop a penny from the top of the Empire State Building" question, or alternatively the "if you shoot a bullet straight up into the air and it falls back" question. Seems like Mythbusters addressed this and found that falling bullets or pennies would hurt (like paintballs) but not cause serious injury.
hendric
QUOTE (helvick @ Dec 18 2007, 03:07 PM) *
Yes but grenade fragments travel a few tens of meters at most - if they were to travel through hundreds or thousands of meters of air they would cool rapidly.


Doesn't that depend on their speed though? Above a certain speed, they are going to get hotter, and below that speed, they are going to cool off. I could easily see that switchover at 1-2km/sec. Granted, it might be quickly decelerating, but a metal fragment is pretty darn dense. Bullets can travel for miles, so I can see a small, mostly metallic fragment, starting off hot at 3-4 km/sec, travelling for quite some distance, potentially tens of miles, and still be hot enough to burn bone upon impact.

Dr. Burt, where are you on this? These fragments are proof, so to speak, of an impact surge! How does their size compare to the blueberries and other impact surge fragments?

With that said, it's interesting there are actually different sizes of fragments in the same tusk. I'm sure a reasonable model could be made of how far away the impact would have to be to allow fragments of the minimum size to penetrate the tusks. At the least, the model should give a minimum distance.
helvick
QUOTE (ngunn @ Dec 19 2007, 03:34 PM) *
Maybe not if they are fallout from a mushroom cloud.

Small particles falling out of a debris\mushroom cloud will never exceed the terminal velocity for such a particle which will be too slow to penetrate flesh and bone. Some examples:
Nickel Iron fragment - Density 8000kg/m^3, 1cm diameter, mass 4g, volume 0.5cc, Drag Coeff 0.7, Terminal Velocity 35m/sec (80mph)
Drop that to a 1mm diameter and the terminal velocity drops to 11m/sec (25mph)
Drop that to 0.1mm diameter and the terminal velocity drops to 3.5m/sec (8mph)

I need a bit more time to figure out range vs initial velocity but rest assured that it happens very fast.

If you take the 1mm grain and assume an initial velocity of 5km/sec the initial deceleration due to drag is just below 2000 km/sec^2. That's not going very far - frankly I'd be surprised if it went more than 50m before hitting it's terminal velocity.

There is also the fact that the loss in kinetic energy needs to be bled off as heat and at higher velocities the particle will just atomize.
djellison
Yeah - the maths of this makes the likelihood of a particle of that size, traveling fast enough to do that damage very very small.

Doug
dvandorn
Sounds like we ought to move this discussion to the "Tiny Craters" thread over in the MER forum... rolleyes.gif

-the other Doug
nprev
QUOTE (djellison @ Dec 19 2007, 08:56 AM) *
...makes the likelihood of a particle of that size, traveling fast enough to do that damage very very small.

Doug


I'm inclined to agree, but damned if I can think of another mechanism more effective then an airburst. This may have been an extremely rare event (thank God; it sounds truly ghastly).

oDoug...yeah....makes you wonder a bit, doesn't it? This sort of thing may well be far more common on Mars, since the atmospheric drag would be so much smaller on frags. Better make sure future explorers bring Kevlar flak jackets...I'll donate mine in six months when I retire from the Reserves! tongue.gif
ngunn
I really think we need Don Burt here, but I think he would say that the 'air' through which the particles were falling would also have been pretty hot, like the cloud from an explosive volcanic eruption. The animals would have suffered burns from that alone, and the spherules would have experienced less cooling (and less deceleration) than if they had been falling through ordinary cool air. The whole collapsing column of heated gas and solids would have been descending on them. I imagine them pinned to the ground and in considerable distress.
PDP8E
Fascinating mystery!

Airburst? rocky meteors maybe...but iron ??

The power to launch these little BBs so near to beasts and it doesn't kill them?

We need to find the site.. somehow...and let the geologists take over...

this is a juicy story, I hope it pans out for some lucky young ground pounder!
dburt
QUOTE (ngunn @ Dec 19 2007, 03:27 PM) *
I really think we need Don Burt here, but I think he would say that the 'air' through which the particles were falling would also have been pretty hot, like the cloud from an explosive volcanic eruption. The animals would have suffered burns from that alone, and the spherules would have experienced less cooling (and less deceleration) than if they had been falling through ordinary cool air. The whole collapsing column of heated gas and solids would have been descending on them. I imagine them pinned to the ground and in considerable distress.

Well, this is the 3rd time my name has been mentioned here, and two people sent me personal messages, so I guess it's time to share my utter ignorance. smile.gif I wasn't at AGU and haven't even downloaded the poster, so I only know what I've read here and in the news story. First, other than having been caused by impact, these observations probably have little direct relation to the slightly Ni-enriched hematitic spherules observed on Mars, particularly at Meridiani (with some spherules also spotted at Gusev). From their uniform size and sphericity, and internal granularity, we presume that the Mars spherules could have formed by particle accretion in a condensing sticky, steamy surge cloud (i.e., that they are "accretionary lapilli" or a related species), with turbulence counteracting the force of gravity as they got larger. When the spherules hit the ground rolling and bouncing, they were probably travelling no faster than and were not much hotter than the turbulent particle-rich ground-hugging cloud as a whole. If you were a mammoth standing in the way, you probably would have been knocked over and possibly shredded and parbroiled, but the spherules probably wouldn't be embedded in your tusks, locally burning them, and you probably wouldn't survive.

The tiny embedded hot Fe,Ni metal particles discussed here seem to have been travelling somewhat faster than their medium, and a "blunderbuss" or shot-gun like effect has been suggested. That might not be too far off the mark, according to this second AGU-related story about a small directed blast for the 1908 Tunguska event which came out at the same time (and consistent with ngunn's hypothesis above):
http://www.sandia.gov/news/resources/relea...7/asteroid.html

So in the Mars spherule case you are talking about possible depositional effects of a distant large crater-forming (ground-burst type) impact, and in the Alaska case possibly about a Tunguska-like small (air-burst type) impact high in the sky, one that might have produced a narrow blast directed downwards.

Just my uninformed suggestion. Thanks to the badastronomy.com website for the original link to that second story.

-- HDP Don
ngunn
Thank you for that, Don, very informative (and very pretty movies). So there is a clear distinction between hot melt spherules being impelled downward by the original momentum of an incoming bolide and cooler slower-moving accretion lapilli that form in the cloud after a ground blast - and these latter do not fit the present case.
dburt
QUOTE (ngunn @ Dec 21 2007, 02:08 AM) *
Thank you for that, Don, very informative (and very pretty movies). So there is a clear distinction between hot melt spherules being impelled downward by the original momentum of an incoming bolide and cooler slower-moving accretion lapilli that form in the cloud after a ground blast - and these latter do not fit the present case.

I think you basically have it, although I can think of no compelling reason why the hot particles being impelled downward need be melts, or spherules, as far as that goes (especially by the time they hit the poor mammoth). After major impacts, uniformly sized spherules can form by accretion of bulk solids from vapors, melts, and/or sticky particles while they are tumbling chaotically in a turbulent cloud. They are spherical because of the chaotic manner in which they grow (whereas tektites, glassy impact melt droplets that "splashed out" of the crater and congealed in the air, tend to be teardrop shaped or even more irregular). Perfectly spherical carbonate ooids (in oolitic limestone) are believed to form chaotically also, as wave action rolls them about during growth.

Of course, spheroidal growths called concretions (compare carbonate pisoids) can also form by direct chemical precipitation from aqueous fluids, but this requires rather special conditions (slow or no fluid flow, homogeneous physical medium, widely-spaced uniform nucleation, chemical driving force uniformly applied, etc.). Usually, concretions (also pisoids) are rounded but non-spherical (flattened and/or elongated), of various mixed sizes up to quite large, and concentrated (clumped together) at some sort of chemical reaction front (as where different brines have mixed with or diffused into each other). Pardon the mini-lecture, but I just can't stop myself when it comes to those misunderstood lumps and clumps ... smile.gif

-- HDP Don
ngunn
QUOTE (dburt @ Dec 22 2007, 04:08 AM) *
I think you basically have it, although I can think of no compelling reason why the hot particles being impelled downward need be melts, or spherules, as far as that goes (especially by the time they hit the poor mammoth).


Indeed not though the bone/tusk damage suggests roundish and rather uniformly sized 'shot', which was why I particularly wanted to consult you as our in-house expert on Earth impact phenomena (and particularly sherules). I think most of us have a lot of imagining to do before we can envisage the full horror of a cosmic impact. You've probably done it already.
dburt
QUOTE (ngunn @ Dec 22 2007, 04:44 PM) *
...why I particularly wanted to consult you as our in-house expert on Earth impact phenomena (and particularly sherules). I think most of us have a lot of imagining to do before we can envisage the full horror of a cosmic impact. You've probably done it already.

Thanks much for the Christmas present (compliment), but I'd hardly classify myself as an impact expert. I had no particular interest in or experience with impacts until the very first MER images started coming back. Then, when the images didn't look very much like what they were supposed to (i.e., evaporitic lake deposits with concretions), I had to ask myself, what else could they possibly be? And impact deposits seemed like the only reasonable alternative to me and to my colleague Paul Knauth, and still do. Since then I've been trying to educate myself, but it hasn't been easy. I doubt if anyone, least of all me, could fully envisage a cosmic impact, although personally I might refer to the "wonder" of it unless I was in the target area. But that's just the scientist in me speaking. smile.gif

-- HDP Don
dburt
QUOTE (Rob Pinnegar @ Dec 13 2007, 09:00 PM) *
Yeah, I read this one the other day. Very peculiar (and, really, more-or-less unbelievable)...

I'll also quote Helvick: "I can't see how this could be possible." These two early reactions here at UMSF (very different from mine, I freely admit) have been formulated in far more detail, with documentation and numerous literature citations, in the January, 2008 issue of GSA Today, the monthly newsletter of the Geological Society of America, p. 37-38, here:
http://www.gsajournals.org/perlserv/?reque...;issn=1052-5173
The authors are Nicholas Pinter and Scott Ishman of SIU and the full 2-page article (amazingly outspoken) is here:
http://www.gsajournals.org/perlserv/?reque...2FGSAT01801GW.1

Basically, using phrases such as "observations and claims so wild," "Frankenstein monster," "runs roughshod over ... evidence," "ignore extensive literature," and "played out primarily in the popular press," they ascribe the microparticles and microspherules to the normal constant infall of sand-sized micrometeorites, plus normal wildfires, and the extinctions of giant mammals to conventional causes (e.g., climate change and the influence of early humans). Just FYI, and DBETYR (don't believe everything you read).

-- HDP Don
nprev
Boy howdy... blink.gif ...yeah, I'd call that "outspoken" all right, Don.

Can't disagree, though; always like to see pushback & a rally cry for critical thinking, esp. when presenting very unusual (in this case, nearly anomalous) findings. Seems like there's a very human tendency to assign recently recognized phenomena--in this case, terrestrial impact events--as probable causes for poorly understood observations.

Still...this particular case is bizarre. I'm keeping my mind open.
TheChemist
If I understood well, this refers mainly to a 12,9 ka impact that seems to have been proposed by the same author in different abstracts of the same (?) conference. I think these abstracts are not available yet on the net.

The abstract which is the subject of this thread refers to a supposed 30-35 ka impact. Would not a "normal constant infall of sand-sized micrometeorites " result in a more common occurence of mammoth skulls looking like those described in this thread ?

So although the criticism is good and absolutely necessary against the general "easy solution through impact" fever, for the specific case discussed in this thread I remain in the dark.
And I am sure there are a lot more scientists (maybe 1 out of 2) responsible for the loss of scientific credibility in the recent decades through "extensive advertising" of their own work. A bit too outspoken.
dburt
QUOTE (TheChemist @ Jan 11 2008, 10:04 AM) *
If I understood well, this refers mainly to a 12,9 ka impact that seems to have been proposed by the same author in different abstracts of the same (?) conference. I think these abstracts are not available yet on the net.

The abstract which is the subject of this thread refers to a supposed 30-35 ka impact. Would not a "normal constant infall of sand-sized micrometeorites " result in a more common occurence of mammoth skulls looking like those described in this thread ?..

Actually, as I recall (I don't have it in front of me), the GSA Today article discusses both events - the older one is supposed to have produced mega-tsunamis (debunked by the article as eolian dunes); the younger one the extinctions. Recent posts here seem to have been referring to the younger extinction event.

-- HDP Don
nprev
Just adding this as a data input: seems that fragments from a conventional grenade (0.5kg of explosive) can travel as much as a mile (1.6km) from the detonation point. (Would cite the reference, but it's not publicly accessible, though not classified in any way.) Don't know if anyone's ever measured the frags' temperatures, though.
dburt
QUOTE (TheChemist @ Jan 11 2008, 10:04 AM) *
If I understood well, this refers mainly to a 12,9 ka impact that seems to have been proposed by the same author in different abstracts of the same (?) conference. I think these abstracts are not available yet on the net.

The abstract which is the subject of this thread refers to a supposed 30-35 ka impact. Would not a "normal constant infall of sand-sized micrometeorites " result in a more common occurence of mammoth skulls looking like those described in this thread ?

Further comment, made in less of a rush (after looking at the GSA Today article again). Although the original news story refers to the older time period, the more complete BBC story contains the original author quote: "The date could really be anywhere from 13,000 to 35-40,000 years ago." and the reporter then states, "The team believes there must still be peppered tusks out there that can be dated to 13,000 years ago." Certainly the authors (Firestone et al.) are the same and their hypothesis is the same. The mega-tsunami part of the GSA Today article actually refers to more recent (Holocene, or latest 10,000 years) alleged impact events - my memory over the weekend was faulty. And I freely admit I still haven't read the original AGU abstracts or AGU poster.

-- HDP Don
TheChemist
Thanks Don, I had a look at the AGU abstract, and the Science and GSA today articles, but I had missed the BBC article.
So now that I have read that too, it is clear to me, that the authors claim that since the skulls might be exposed and marked later with the fragments, it could be that there is a single Holocene event that explains the older marked skull too.
They are still far away from proving anything, but whether they are wrong or not is still a matter of scientific debate, at least imho.
Science takes time, and one never knows what's unearthed in the future.
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