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https://www.scientificamerican.com/article/no-there-wasnt-an-advanced-civilization-12-000-years-ago/ https://www.scientificamerican.com/article/no-there-wasnt-a

https://www.scientificamerican.com/article/no-there-wasnt-an-advanced-civilization-12-000-years-ago/ https://www.scientificamerican.com/article/no-there-wasnt-an... should accompany this. The whole younger Dryas advanced civilization think could have been avoided entirely and the point about ice melt rates would have been fine.

ncmncm 6y ago
That SA article has been overtaken by events. We still don't have any evidence of early, drowned civilizations, but the comet strike now seems to be responsible for extinctions in both South America and Africa. As an aside, you don't need a crater. Multiple airbursts over a wide area, Tunguska style, provide plenty of devastation. You might be able to believe in mass extinctions caused by newly arrived humans in South America, but explaining the African ones the same way ought to get you funny looks. The more you think about that, the less plausible human responsibility for the American extinctions becomes.
- shawnb576 6y ago
  Do you have citations for this?
  - ncmncm 6y ago
    A very good references list is at the end of "Deadly Voyager", by James Lawrence Powell (available free on Kindle to Prime subscribers), and is reproduced at http://deadlyvoyager.net/References/ http://deadlyvoyager.net/References/
- robbiep 6y ago
  Interestingly I was reading about this this morning whilst reviewing my old crackpot hero Graham Hancock (reading fingerprints of the gods at a young age had me fascinated about this mythical ancient civilisation for which exceptional claims are made but very little evidence). This is a great rebuttal of the whole YDIH. Specifically regarding the possibility of air bursts, (0) says this: The firestorm began in 2007 when Richard Firestone and numerous colleagues proposed that it was a comet strike of “multiple ET [extraterrestrial] airbursts along with surface impacts” that occurred at 12,900 years ago that initiated the YD.”23 The paper was full of impressive evidence gathered from 10 sites where a carbon-rich layer (referred to as the “black mat”) marked what they claimed was the end of the Clovis culture in North America: “The in situ bones of extinct Pleistocene megafaunas, along with Clovis tool assemblages, occur below this black layer but not within or above it.” They reported that sediments directly below the black mat were enriched in magnetic grains, iridium, magnetic microspherules, charcoal, soot, carbon spherules, glass-like carbon containing nanodiamonds and fullerenes containing extraterrestrial helium. They explained that the soot, charcoal, spherules, etc. were the result of extensive and intense forest fires initiated by the airbursts. Melting of the Laurentide Ice Sheet would have dumped copious quantities of melt water into the Atlantic, thereby disrupting the density currents and bringing on the cooling. Over the years, however, support for the YDIH has been undermined. Nearly every aspect of the original evidence has been challenged by a host of scientists in various fields. Only one of the indicators, iridium, has been commonly used as an impact marker, and the iridium data have not always been reproducible. The iridium concentrations can also be explained by terrestrial origins.24, 25 Nor do nanodiamonds require extraterrestrial events. The absence of any impact craters at the beginning of the YD worldwide is the most disconcerting evidence against YDIH, as is the lack of control for the age of sediments/black mat at or near the YD boundary. Elsewhere it remarks that even should air bursts be the case, from a massive comet breaking up or multiple comets breaking up, there still must be corresponding craters of the size of Meteor crater to correspond to the scale of the proposed devestation In addition to these arguments against the YDIH, it is difficult to imagine how an airburst/impact could annihilate the North American mammal megafauna and Clovis culture and initiate huge wild fires, without leaving any evidence in the way of massive flooding or impact features. Vance Holliday and his colleagues argue that “no physical mechanism is known to produce an airburst that would affect the entire continent.”27 They also point out that any comet strike large enough to affect an entire continent would leave a detectable crater even if it struck the ice sheet. To get around this glaring problem, the Firestone group proposed that the comet broke up upon entry into earth’s atmosphere. But according to physicist Mark Boslough and his colleagues,28 that would produce “more than a million Meteor craters” (the size of the crater in central Arizona) based on the comet size postulated by Firestone and his cohorts.29, 30 While the Firestone group claims that the comet strike was responsible for the disappearance of the 37 mammal megafauna genera specifically in North America, extinctions occurred on other continents, most notably South America, where at least 52 mammal genera disappeared. And not all those genera disappeared synchronously at the YD boundary! Instead, megafauna extinctions on continents and islands seem to correlate with the arrival of humans. The thinking goes that these huge megafauna would have had no reason to fear humans, and were probably easy pickings for the newly arriving hunter-gatherers. Scientists have also been a bit incredulous that a comet strike could wipe out all the megafauna as far south as Patagonia, while leaving mammoths alive and well on St. Paul Island, Alaska until 3,700 years ago (0) https://www.skeptic.com/reading_room/defant-analysis-of-hancock-claims-in-magicians-of-the-gods/ https://www.skeptic.com/reading_room/defant-analysis-of-hanc...
  - ncmncm 6y ago
    Graham Hancock has some wacky ideas, but is always (and unusually) careful to distinguish fact from speculation. (And his wife's photos are excellent.) It is a circular argument that extinctions coincide with arrival of humans: that humans arrived at that time is an assumption, and one that is losing credibility. Anyway, as noted, you also need to explain why humans didn't wipe out African megafauna (no, wariness doesn't), and also why Clovis culture disappeared suddenly across the continent. One may doubt they starved immediately after wiping out the last of their prey. You can quibble all you like about nanodiamond crystallography and carbon granules, but sharp platinum peaks at 200x above background, found at dozens of sites, need better explanation. It is curious--telling, even--that critics dwell on osmium isotope ratios and never mention platinum. As was explained in connection with the K-T extinction event that attracted similar derision from geologists who had to retire before it got a fair hearing, anything that happened, can.
    - ncmncm 6y ago
      It is also telling that we find certain bolides to have an osmium isotope ratio in the range they consider a problem--and they know about those.
  - cneu 6y ago
    That has been in 2017, when there was also this famous discussion between Hancock, Carlson and Shermer on the JRE. Shermer is the publisher of Skeptic Magazine, which you quoted. He recently tweeted this: https://twitter.com/michaelshermer/status/1237559469967421440 https://twitter.com/michaelshermer/status/123755946996742144...
    - ncmncm 6y ago
      tl;dr: mea culpa Similarly Marc Defant, former skeptic: https://www.marcdefant.com/2020/06/05/the-younger-dryas-impact-hypothesis/ https://www.marcdefant.com/2020/06/05/the-younger-dryas-impa... Changing one's mind in the face of evidence is admirable and distressingly rare. Speaking up to admit having been wrong is oh-so-much rarer.
- throwaway5752 6y ago
  I've seen you post before on this. The whole catastrophist label seems overly broad, and some parts are reasonable while other parts are less so. How advanced do you think this civilization was? Do you think it was the Clovis people? I think the megafauna extinction as support for a catastrophic event is very poor. You see multiple waves of megafauna extinctions, each preceded by human introduction. Places without human presence had megafauna into the late 20th century. I'm not saying it didn't happen, but I'm saying it's unconvincing. And air bursts of that magnitude and coverage don't square with fossil or sediments. But ... impacts aren't required for this. Maybe there was a culture that was relatively advanced. The Mississippian structures were huge. Incan and Mayan cultures were advanced based on contemporary cultures. Anyway, I'm curious what you believe is the case.
  - ncmncm 6y ago
    This has all already been responded to. Except, the Inka, Mayan, Missouri and Amazon civilizations are 10+ millennia too late to be relevant, but in that they were unknown to Europeans until 500, 50, or 15 years ago. I don't know anything about a pre-6000 BP civilization except that it is possible in principle, and evidence might be underwater. I would look first off the west coast of India, south of Pakistan and near old Harappan cities, where buildings are known of, under 60 ft of water. They snag fishermen's nets.

ncmncm 6y ago

That SA article has been overtaken by events. We still don't have any evidence of early, drowned civilizations, but the comet strike now seems to be responsible for extinctions in both South America and Africa. As an aside, you don't need a crater. Multiple airbursts over a wide area, Tunguska style, provide plenty of devastation. You might be able to believe in mass extinctions caused by newly arrived humans in South America, but explaining the African ones the same way ought to get you funny looks. The more you think about that, the less plausible human responsibility for the American extinctions becomes.

shawnb576 6y ago
Do you have citations for this?
- ncmncm 6y ago
  A very good references list is at the end of "Deadly Voyager", by James Lawrence Powell (available free on Kindle to Prime subscribers), and is reproduced at http://deadlyvoyager.net/References/ http://deadlyvoyager.net/References/
robbiep 6y ago
Interestingly I was reading about this this morning whilst reviewing my old crackpot hero Graham Hancock (reading fingerprints of the gods at a young age had me fascinated about this mythical ancient civilisation for which exceptional claims are made but very little evidence). This is a great rebuttal of the whole YDIH. Specifically regarding the possibility of air bursts, (0) says this: The firestorm began in 2007 when Richard Firestone and numerous colleagues proposed that it was a comet strike of “multiple ET [extraterrestrial] airbursts along with surface impacts” that occurred at 12,900 years ago that initiated the YD.”23 The paper was full of impressive evidence gathered from 10 sites where a carbon-rich layer (referred to as the “black mat”) marked what they claimed was the end of the Clovis culture in North America: “The in situ bones of extinct Pleistocene megafaunas, along with Clovis tool assemblages, occur below this black layer but not within or above it.” They reported that sediments directly below the black mat were enriched in magnetic grains, iridium, magnetic microspherules, charcoal, soot, carbon spherules, glass-like carbon containing nanodiamonds and fullerenes containing extraterrestrial helium. They explained that the soot, charcoal, spherules, etc. were the result of extensive and intense forest fires initiated by the airbursts. Melting of the Laurentide Ice Sheet would have dumped copious quantities of melt water into the Atlantic, thereby disrupting the density currents and bringing on the cooling. Over the years, however, support for the YDIH has been undermined. Nearly every aspect of the original evidence has been challenged by a host of scientists in various fields. Only one of the indicators, iridium, has been commonly used as an impact marker, and the iridium data have not always been reproducible. The iridium concentrations can also be explained by terrestrial origins.24, 25 Nor do nanodiamonds require extraterrestrial events. The absence of any impact craters at the beginning of the YD worldwide is the most disconcerting evidence against YDIH, as is the lack of control for the age of sediments/black mat at or near the YD boundary. Elsewhere it remarks that even should air bursts be the case, from a massive comet breaking up or multiple comets breaking up, there still must be corresponding craters of the size of Meteor crater to correspond to the scale of the proposed devestation In addition to these arguments against the YDIH, it is difficult to imagine how an airburst/impact could annihilate the North American mammal megafauna and Clovis culture and initiate huge wild fires, without leaving any evidence in the way of massive flooding or impact features. Vance Holliday and his colleagues argue that “no physical mechanism is known to produce an airburst that would affect the entire continent.”27 They also point out that any comet strike large enough to affect an entire continent would leave a detectable crater even if it struck the ice sheet. To get around this glaring problem, the Firestone group proposed that the comet broke up upon entry into earth’s atmosphere. But according to physicist Mark Boslough and his colleagues,28 that would produce “more than a million Meteor craters” (the size of the crater in central Arizona) based on the comet size postulated by Firestone and his cohorts.29, 30 While the Firestone group claims that the comet strike was responsible for the disappearance of the 37 mammal megafauna genera specifically in North America, extinctions occurred on other continents, most notably South America, where at least 52 mammal genera disappeared. And not all those genera disappeared synchronously at the YD boundary! Instead, megafauna extinctions on continents and islands seem to correlate with the arrival of humans. The thinking goes that these huge megafauna would have had no reason to fear humans, and were probably easy pickings for the newly arriving hunter-gatherers. Scientists have also been a bit incredulous that a comet strike could wipe out all the megafauna as far south as Patagonia, while leaving mammoths alive and well on St. Paul Island, Alaska until 3,700 years ago (0) https://www.skeptic.com/reading_room/defant-analysis-of-hancock-claims-in-magicians-of-the-gods/ https://www.skeptic.com/reading_room/defant-analysis-of-hanc...
- ncmncm 6y ago
  Graham Hancock has some wacky ideas, but is always (and unusually) careful to distinguish fact from speculation. (And his wife's photos are excellent.) It is a circular argument that extinctions coincide with arrival of humans: that humans arrived at that time is an assumption, and one that is losing credibility. Anyway, as noted, you also need to explain why humans didn't wipe out African megafauna (no, wariness doesn't), and also why Clovis culture disappeared suddenly across the continent. One may doubt they starved immediately after wiping out the last of their prey. You can quibble all you like about nanodiamond crystallography and carbon granules, but sharp platinum peaks at 200x above background, found at dozens of sites, need better explanation. It is curious--telling, even--that critics dwell on osmium isotope ratios and never mention platinum. As was explained in connection with the K-T extinction event that attracted similar derision from geologists who had to retire before it got a fair hearing, anything that happened, can.
  - ncmncm 6y ago
    It is also telling that we find certain bolides to have an osmium isotope ratio in the range they consider a problem--and they know about those.
- cneu 6y ago
  That has been in 2017, when there was also this famous discussion between Hancock, Carlson and Shermer on the JRE. Shermer is the publisher of Skeptic Magazine, which you quoted. He recently tweeted this: https://twitter.com/michaelshermer/status/1237559469967421440 https://twitter.com/michaelshermer/status/123755946996742144...
  - ncmncm 6y ago
    tl;dr: mea culpa Similarly Marc Defant, former skeptic: https://www.marcdefant.com/2020/06/05/the-younger-dryas-impact-hypothesis/ https://www.marcdefant.com/2020/06/05/the-younger-dryas-impa... Changing one's mind in the face of evidence is admirable and distressingly rare. Speaking up to admit having been wrong is oh-so-much rarer.
throwaway5752 6y ago
I've seen you post before on this. The whole catastrophist label seems overly broad, and some parts are reasonable while other parts are less so. How advanced do you think this civilization was? Do you think it was the Clovis people? I think the megafauna extinction as support for a catastrophic event is very poor. You see multiple waves of megafauna extinctions, each preceded by human introduction. Places without human presence had megafauna into the late 20th century. I'm not saying it didn't happen, but I'm saying it's unconvincing. And air bursts of that magnitude and coverage don't square with fossil or sediments. But ... impacts aren't required for this. Maybe there was a culture that was relatively advanced. The Mississippian structures were huge. Incan and Mayan cultures were advanced based on contemporary cultures. Anyway, I'm curious what you believe is the case.
- ncmncm 6y ago
  This has all already been responded to. Except, the Inka, Mayan, Missouri and Amazon civilizations are 10+ millennia too late to be relevant, but in that they were unknown to Europeans until 500, 50, or 15 years ago. I don't know anything about a pre-6000 BP civilization except that it is possible in principle, and evidence might be underwater. I would look first off the west coast of India, south of Pakistan and near old Harappan cities, where buildings are known of, under 60 ft of water. They snag fishermen's nets.