The Younger-Dryas period was an episode of extreme cooling right at the tail end of the last ice age. In 2007, a team of researchers published a shocking find. From around 50 archaeological sites across North America, all dating to the Clovis period (~13,000 BP), there seemed to be evidence for a massive, catastrophic event. They proposed that
“one or more large, low-density ET objects exploded over northern North America, partially destabilizing the Laurentide Ice Sheet and triggering YD cooling. The shock wave, thermal pulse, and event-related environmental effects (e.g., extensive biomass burning and food limitations) contributed to end-Pleistocene megafaunal extinctions and adaptive shifts among PaleoAmericans in North America.” (Firestone et al. 2007:16016)
Just like that, the Younger Dryas Impact Hypothesis was born. This sent shockwaves through the archaeological community. If true, it would resolve several open questions all at once. The Younger-Dryas itself would be explained, but so would the extinction of many genera of ice age megafauna. It would also explain the disappearance of the Clovis culture. It’s a great theory. A lot of people were really excited. But then scientists tried to take the next step, and test the hypothesis further. Many tried to replicate elements of Firestone et al.’s study. The original authors said that in the layers of sediment from the Younger Dryas period which they studied, they found
“a thin, discrete layer with varying peak abundances of (i) magnetic grains with iridium, (ii) magnetic microspherules, (iii) charcoal, (iv) soot, (v) carbon spherules, (vi) glass-like carbon containing nanodiamonds, and (vii) fullerenes with ET helium”
So that’s what others set out to replicate. Unfortunately, these attempts have been consistently unsuccessful. For example, one study focused on the elevated levels of iridium the original paper had reported, but they found “no evidence of an extraterrestrial (ET)-PGE enrichment anomaly” (Paquay et al. 2009:21505) in any of their samples. Another team, with the first author being my Master’s advisor Todd Surovell, looked for the magnetic particles reported in the original paper. They also came up short, finding “no distinct peak in magnetic grains or microspherules uniquely associated with the YD” and “no support for an extraterrestrial cause of the YD event and New World Pleistocene extinctions” (Surovell et al. 2009:18155).
Firestone et al. described the ET impact layer from many of these sites as a distinctive “black mat.” Their results suggested a clean sequence: Clovis and megafauna are doing their thing, there’s an abrupt deposition of this anomalous layer at the same moment everywhere, and then no Clovis or megafauna on the other side. That sounds pretty convincing. A study several years later, in 2015, also supported this idea with a bayesian analysis of radiocarbon dates from Younger Dryas boundary layers at sites on four continents, showing that it really happened everywhere at the same time (Kennett et al. 2015). But… that wasn’t really an independent study. It includes many of the authors from the original paper. So another team looked into their radiocarbon dates more closely. Here’s what they did:
“we first aggregate 14C measurements from Northern Hemisphere YDB sites. We also aggregate 14C measurements associated with a known synchronous event, the Laacher See volcanic eruption. We then use a Monte Carlo simulation to evaluate the magnitude of variability expected in a 14C dataset associated with a synchronous event. The simulation accounts for measurement error, calibration uncertainty, “old wood” effects, and laboratory measurement biases.” (Jorgeson et al. 2019:123)
And… their results did not support the idea that these layers were deposited at the same time, suggesting that however they were deposited, it wasn’t from an ET impact. Conveniently, there are some other explanations for the “black mats” of the Younger Dryas. For example, one study found that soils in wetlands can accrue many of the same materials found by Firestone et al., so some of the layers at these Clovis sites might be showing us environmental changes, rather than an ET impact. (Pigati et al. 2012)
Another article points out that while many of the materials Firestone et al. reported make sense individually, they shouldn’t be occurring together in a single ET object. “Any one of these might be a credible extraterrestrial source, but together they are a Frankenstein monster, incompatible with any single impactor or any know impact event.” (Pinter and Ishman 2008:37). Meanwhile, another team found no evidence for a population decline at the end of the Younger Dryas (Buchanan et al. 2008).
For all of these reasons and more, researchers have been turning against the idea that such an impact ever took place. Despite what certain pseudo-archaeologists with recent hit shows on Netflix who appeared on the Joe Rogan Experience claim, the Younger-Dryas Impact Hypothesis has not delivered convincing evidence. Even though it would be pretty cool.
Buchanan, B., Collard, M., & Edinborough, K. (2008). Paleoindian demography and the extraterrestrial impact hypothesis. Proceedings of the National Academy of Sciences - PNAS, 105(33), 11651-11654. https://doi.org/10.1073/pnas.0803762105
Firestone, R. B., West, A., Kennett, J. P., Becker, L., Bunch, T. E., Revay, Z. S., Schultz, P. H., Belgya, T., Kennett, D. J., Erlandson, J. M., Dickenson, O. J., Goodyear, A. C., Harris, R. S., Howard, G. A., Kloosterman, J. B., Lechler, P., Mayewski, P. A., Montgomery, J., Poreda, R., . . . Wolbach, W. S. (2007). Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the younger dryas cooling. Proceedings of the National Academy of Sciences - PNAS, 104(41), 16016-16021. https://doi.org/10.1073/pnas.0706977104
Jorgeson, I. A., Breslawski, R. P., & Fisher, A. E. (2020). Radiocarbon simulation fails to support the temporal synchroneity requirement of the younger dryas impact hypothesis. Quaternary Research, 96, 123-139. https://doi.org/10.1017/qua.2019.83
Kennett, J. P., Kennett, D. J., Culleton, B. J., Tortosa, J. E. A., Bischoff, J. L., Bunch, T. E., Daniel, I. R., Erlandson, J. M., Ferraro, D., Firestone, R. B., Goodyear, A. C., Israde-Alcántara, I., Johnson, J. R., Pardo, J. F. J., Kimbel, D. R., LeCompte, M. A., Lopinot, N. H., Mahaney, W. C., Moore, A. M. T., . . . West, A. (2015). Bayesian chronological analyses consistent with synchronous age of 12,835–12,735 cal B.P. for younger dryas boundary on four continents. Proceedings of the National Academy of Sciences - PNAS, 112(32), E4344-E4353. https://doi.org/10.1073/pnas.1507146112
Paquay, F. S., Goderis, S., Ravizza, G., Vanhaeck, F., Boyd, M., Surovell, T. A., Holliday, V. T., Haynes, C. V. J., & Claeys, P. (2009). Absence of geochemical evidence for an impact event at the bølling-Allerød/Younger dryas transition. Proceedings of the National Academy of Sciences - PNAS, 106(51), 21505-21510. https://doi.org/10.1073/pnas.0908874106
Pigati, J. S., Latorre, C., Rech, J. A., Betancourt, J. L., Martínez, K. E., & Budahn, J. R. (2012). Accumulation of impact markers in desert wetlands and implications for the younger dryas impact hypothesis. Proceedings of the National Academy of Sciences - PNAS, 109(19), 7208-7212. https://doi.org/10.1073/pnas.1200296109
Pinter, N., & Ishman, S. E. (2008). Impacts, mega-tsunami, and other extraordinary claims. GSA Today, 18(1), 37. https://doi.org/10.1130/GSAT01801GW.1
Surovell, T. A., Holliday, V. T., Gingerich, J. A. M., Ketron, C., Haynes, C. V., Hilman, I., Wagner, D. P., Johnson, E., & Claeys, P. (2009). An independent evaluation of the younger dryas extraterrestrial impact hypothesis. Proceedings of the National Academy of Sciences - PNAS, 106(43), 18155-18158. https://doi.org/10.1073/pnas.0907857106
However many nations live in the world today, however many countless people, they all had but one dawn." ~Anonymous, Popul Vuh
Every step you take has already been taken. Every story has already been told. The land is not newly discovered, so old with legends you might mistake them for rocks." ~Craig Childs
The present contains nothing more than the past, and what is found in the effect was already in the cause." ~Henri Bergson
Archaeologists may not always see the trees, but we capture the forest with great clarity" ~Robert Kelly
The past is never dead; it's not even past." ~William Faulkner
No civilization has survived forever. All move toward dissolution, one after the other, like waves of the sea falling upon the shore. None, including ours, is exempt from the universal fate.” ~Douglas Preston
If you go into a museum and look at antiquities collected there, you can be sure that the vast bulk of them were found not in buildings but in graves." ~Leonard Woolley
Ice breathes. Rock has tides. Mountains ebb and flow. Stone pulses. We live on a restless earth.” ~Robert Macfarlane
We always stand on the shoulders of our ancestors, whether or not we look down to acknowledge them." ~David Anthony
That which always was, and is, and will be everliving fire, the same for all, the cosmos, made neither by god nor man, replenishes in measure as it burns away." ~Heraclitus
Shamanism is not simply a component of society: on the contrary, shamanism, together with its tiered cosmos, can be said to be the overall framework of society." ~David Lewis-Williams
Opened are the double doors of the horizon. Unlocked are its bolts." ~Utterance 220 of the Pyramid of Unas
If history were taught in the form of stories, it would never be forgotten." ~Rudyard Kipling
The mountains are fountains of men as well as of rivers, of glaciers, of fertile soil. The great poets, philosophers, prophets, able men whose thoughts and deeds have moved the world, have come down from the mountains." ~John Muir
The ecological thinker is haunted by the consequences of time." ~Garrett Hardin
Through the experience of time, Dasein becomes a ‘being towards death’: without death existence would be care-less, would lack the power that draws us to one another and to the world." ~Iain McGillchrist
The dead outnumber the living fourteen to one, and we ignore the accumulated experience of such a huge majority of mankind at our peril." ~Niall Ferguson
Tell me what you eat and I'll tell you what you are." ~Jean Anthelme Brillat-Savarin
We live in a zoologically impoverished world, from which all the hugest and fiercest, and strangest forms have recently disappeared." ~Alfred Russel Wallace
Humans have dragged a body with a long hominid history into an overfed, malnourished, sedentary, sunlight-deficient, sleep-deprived, competitive, inequitable, and socially-isolating environment with dire consequences." ~Sebastian Junger
Except in geographical scale, tribal warfare could be and often was total war in every modern sense. Like states and empires, smaller societies can make a desolation and call it peace." ~Lawrence Keeley
The first people were aware of the signs and signals of the natural world. Their artifacts were projectiles, blades, and ivory sewing needles, either used on animal products, or made from them, or used to procure them. The world around them was a cycle of animals of all sizes, from voles and falcons to some of the largest mammals seen in human evolution." ~Craig Childs
The number of herbivores sets a cap on the number of carnivores that can live in a region. Of course, adding an additional predator of fairly large body size, like a modern human, would produce repercussions that would ripple though all the other predators in the area and their prey." ~Pat Shipman
When viewed globally, near-time extinctions took place episodically, in a pattern not correlated with climatic change or any known factor other than the spread of our species." ~Paul S. Martin
However splendid our languages and cultures, however rich and subtle our minds, however vast our creative powers, the mental process is the product of a brain shaped by the hammer of natural selection upon the anvil of nature."
Behavior is imitated, then abstracted into play, formalized into drama and story, crystallized into myth and codified into religion- and only then criticized in philosophy, and provided, post-hoc, with rational underpinnings."
I have seen yesterday. I know tomorrow."
We are fire creatures from an ice age." ~Stephen Pyne
Men come and go, cities rise and fall, whole civilizations appear and disappear-the earth remains, slightly modified." ~Edward Abbey
Men and women, empires and cities, thrones, principalities, and powers, mountains, rivers, and unfathomed seas, worlds, spaces, and universes, all have their day, and all must go." ~H. Rider Haggard
One day the last portrait of Rembrandt and the last bar of Mozart will have ceased to be- though possibly a colored canvas and a sheet of notes will remain- because the last eye and the last ear accessible to their message will have gone." ~ Oswald Spengler
All that is human must retrograde if it does not advance."
In the long paleontological perspective, we humans must be considered invasive in any locale except Africa." ~Pat Shipman
Of the gladdest moments in human life, methinks, is the departure upon a distant journey into unknown lands. Shaking off with one mighty effort the fetters of Habit, the leaden weight of Routine, the cloak of many Cares and the slavery of Civilization, man feels once more happy." ~Richard Francis Burton
Sedentary culture is the goal of civilization. It means the end of its own lifespan and brings about its corruption." ~Ibn Khaldun
Tradition is not the worship of ashes, but the preservation of fire." ~Gustav Mahler
As for man, his days are numbered. Whatever he might do, it is but wind." ~The Epic of Gilgamesh
There is a cave in the mind."
Full circle, from the tomb of the womb to the womb of the tomb, we come." ~Joseph Campbell
I feel again a spark of that ancient flame." ~ Virgil
Man is an animal suspended in webs of significance he himself has spun. I take culture to be those webs, and the analysis of it therefore not to be an experimental science in search of law, but an interpretive one in search of meaning." ~Clifford Geertz
In all chaos there is a cosmos, in all disorder a secret order." ~Carl Jung
Man fears time, but time fears the pyramids." ~Arab proverb
Few romances can ever surpass that of the granite citadel on top of the beetling precipices of Machu Picchu, the crown of Inca Land." ~Hiram Bingham
You don't have to be a fantastic hero to do certain things- to compete. You can just be an ordinary chap, sufficiently motivated to reach challenging goals." ~Edmund Hillary
Thousands of tired, nerve-shaken, over-civilized people are beginning to find out that going into the mountains is going home; that wildness is a necessity." ~John Muir
To speak of truth sounds too grand, too filled with the promise of certainty, and we are rightly suspicious of it. But truth will not go away that easily. The statement that ‘there is no such thing as truth’ is itself a truth statement, and implies that it is truer than its opposite, the statement that ‘truth exists’." ~Lain McGillchrist
The Sphinx will always have to be looked after."
Yes, the pyramids have been built, but if you give me 300,000 disciplined men and 30 years I could build a bigger one."
Civilizations exist by geological consent, subject to change without notice."
When at last we anchored in the harbor, off the white town hung between the blazing sky and its reflection in the mirage which swept and rolled over the wide lagoon, then the heat of Arabia came out like a drawn sword and struck us speechless"
The best prophet of the future is the past."
An archaeologist is the best husband a woman can get. The older she gets the more interested he is in her."
Archaeology is the peeping Tom of the sciences. It is the sandbox of men who care not where they are going; they merely want to know where everyone else has been."
What would be ugly in a garden constitutes beauty in a mountain."
I have never been able to grasp the meaning of time. I don't believe it exists. I've felt this again and again, when alone and out in nature. On such occasions, time does not exist."
Myths are public dreams, dreams are private myths. "~Joseph Campbell
In my experience, it is rarer to find a really happy person in a circle of millionaires than among vagabonds."
Always my soul hungered for less than it had"
History is filled with the sound of silken slippers going downstairs, and wooden shoes coming up."
Back home, I'm always focusing on something happening in the future. On expeditions, time stops, and you become like a stone age man, acting on instincts and knowing you are part of the universe."
Genes are rarely about inevitability, especially when it comes to humans, the brain, or behavior. They're about vulnerability, propensities, tendencies." ~Robert Sapolsky
The Land is not old. It only changes, becoming one thing and the next. We are the ones who ascribe age, the brevity of our lives demanding a beginning, middle, and end."
Every age has its own outlook. It is specially good at seeing certain truths and specially liable to make certain mistakes. We all, therefore, need the books that will correct the characteristic mistakes of our own period. And that means the old books."
The only thing that belongs to us is the time."
To abhor hunting is to hate the place from which you came, which is akin to hating yourself in some distant, abstract way." ~Steven Rinella