Deadly Voyager
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DEADLY VOYAGER
DEADLY VOYAGER
THE ANCIENT COMET STRIKE THAT CHANGED EARTH AND HUMAN HISTORY
JAMES LAWRENCE POWELL
© 2020 by James Lawrence Powell
All rights reserved. This book or any portion thereof may not be reproduced or used in any manner whatsoever without the express written permission of the publisher except for the use of brief quotations in a book review.
ISBN: 978-0-578-66677-8
Choose to be puzzled.
— after Will Kyselka
For reference citations (using leading word snatches), figure sources, additional images, and charts, go to deadlyvoyager.net.
Contents
Preface
Prologue: Paradise Lost
Part I: The Younger Dryas Impact Hypothesis
1. The Cycle of Cosmic Catastrophes
2. The Younger Dryas Impact Hypothesis
3. Testing Hypotheses
4. Dead on Arrival?
5. An Independent Evaluation
6. A Cautionary Tale
Part II: Evidence for an Extraterrestrial Event
7. Synchrony
8. Microspherules
9. Precious Stones
10. Wildfires
11. Hiawatha
12. Over Half the Earth’s Surface
13. True Claims
Part III: Effects
14. The Enigma of the Younger Dryas
15. Clovis
16. The Fall of Clovis
17. Great Monsters
18. Paradigm Shifts
19. What if there had Been no Younger Dryas?
PREFACE
Several years ago I attended a talk at a nearby university on the discovery of diamonds so small that they measure only in the billionths of an inch. They had been found concentrated at a geologic boundary whose origin had long puzzled geologists. No, not the Cretaceous-Tertiary (KT) boundary that marks the extinction of the dinosaurs, though nanodiamonds have been found there as well. The boundary in question is only 13,000 years old and captures the time when Earth’s temperature, which had been rising as the Ice Ages waned, suddenly plunged back to glacial frigidity. Scientists call the cold period that ensued the “Younger Dryas,” after a small Arctic flower that flourished in the cooler temperatures. The speaker, a professor at the university, hypothesized that like the KT impact, an extraterrestrial event had caused the Younger Dryas. In this case, the impactor was thought to be a comet.
I was interested in the subject because my first science book, Night Comes to the Cretaceous, had been about the theory that a meteorite strike had killed the dinosaurs. A major focus of that book was the controversy that surrounded the Alvarez Theory, as it came to be named for its two inventors, Luis and Walter Alvarez, father and son. Paleontologists denounced the theory, one calling it “codswallop,” an obscure term but surely no compliment, while meteorite impact specialists embraced it. A knock-down, drag-out, scholarly fight ensued. When I wrote in 1998, I judged that the theory is correct and the evidence that has come to light since has confirmed it beyond reasonable doubt.
As the Space Age has unfolded, appreciation of the role of meteorite impact has grown steadily, with pioneering scientist Gene Shoemaker accurately calling it the “most fundamental process” in the inner solar system. Looking at the pockmarked face of our Moon, we can understand what he meant. The Moon’s myriad craters naturally make us wonder how many asteroids and comets have struck our larger Earth in its billions of years of history. Could the dinosaur killer have been the only one to cause an extinction? Yet search as they may, scientists have been unable to find a second example of an extinction linked to an ET event.
But that was just what the speaker was proposing, because at the onset of the Younger Dryas, almost all the big mammals in the Western Hemisphere suddenly disappeared, including the horse, mammoth, camel, saber-toothed cat, and several dozen more members of the Pleistocene menagerie. Moreover, at the same time the culture of the Clovis people — modern humans just like us — went into sharp decline and their population dropped. Could the Younger Dryas be the long-sought second example of a life-changing ET event that scientists have been seeking?
I left the talk unconvinced but sufficiently intrigued by the Younger Dryas Impact Hypothesis to begin reading the scientific literature about it. I found scores of articles and a considerable amount of supporting evidence. But I also discovered a controversy at least as contentious as the one over the Alvarez Theory. A book about the YDIH, I came to believe, would not only allow the reader to decide whether it is likely to be true, but provide a modern example of how such controversies play themselves out. As I show, the evidence has convinced me that the YDIH is more likely to be true than not, hence the title of this book. If so, this much more recent ET event had world-changing implications for modern humans and for modern science. Without it, the Spanish Conquest would not have occurred. Think how that would have changed world history. And that is only one of the implications of the Younger Dryas Impact Hypothesis.
PROLOGUE: PARADISE LOST
Some 13,000 years ago, Earth’s nearness to the Sun and the tilt and direction of its axis aligned to warm the Northern Hemisphere and end the last Ice Age. As the giant glaciers that had buried much of North America retreated northward, new pathways opened for human migration. Paleo-Indians took advantage and in a remarkably short time spread to Tierra del Fuego on the southern tip of South America. Among the most successful were the Clovis, whose artistic stone projectile points have been found throughout North America and as far south as Venezuela.
The Western Hemisphere teemed with animal life, turning the Great Plains of North America into a prehistoric Serengeti where bison and horses grazed in vast herds. But there were strangers (to us) among them, a fantastic menagerie known only from fossil remains. They included a tiger-sized cat with foot-long, curved incisors; Bison antiquus, larger than an SUV; a sloth that standing erect could look down into a basketball goal; a 135-pound beaver; a one-ton armadillo; mammoths and mastodons; more than a dozen horse species; a huge bear on stilt-like legs; an otter the size of a wolf; a condor with a 24-foot wingspan; and many more.
Then, in only a few years, the warming trend reversed and temperatures in North America suddenly plunged by 6-8°C (11-15°F). They remained low for 1,300 years, then the Earth once again began to submit to its astronomical pacemaker. The cold interval may have ended even more rapidly than it began. Deep ice cores from Greenland show that at the close of the period, temperature rose 5-7°C (9-13°F) in as little as three years. Geologic change almost never happens on that short a timescale.
The geological record reveals the return of glacial conditions by the appearance of the fossil pollen of Dryas octopetala, a pretty little flower that thrives in the temperatures of the Arctic tundra. In recognition, geologists named the cold period the “Younger Dryas” (henceforth YD), “younger” because there had been an earlier period of temporary cooling when the plant had also flourished. Indeed, the ice ages had seen some two dozen sudden temperature oscillations. But the YD was different.
In North America, some 35 of the big mammals — the Pleistocene megafauna — went extinct, including all those listed above. In South America, even more mammals died out. Over the decades, anthropologists have debated two rival theories to explain the extinction: (1) slaughter of “naive” animals by newly arrived, skilled hunters (overkill); or (2) the climatic change that marked the arrival of the YD (facetiously nicknamed “overchill.”)
To gauge the significance of the extinction, imagine that the horse had survived in the Western Hemisphere, rather than going extinct at the YD and having to be re-introduced by Spanish Conquistadors in the 1500s. Paleo-Indians
would certainly have domesticated the horse, as has every other culture with access to horses. That would have allowed the first Americans to spread farther and faster. The Aztecs and Incas would have had thousands of years to develop a horse culture and would not have been cowed into surrender by a few dozen mounted Spaniards an ocean from home. Spain would not have gained its early foothold in the Western Hemisphere, there would have been no Spanish Conquest, and world history would have turned out very differently.
Another notable change at the YD was the disappearance of the Clovis culture. With the YD cooling, their population dropped by 30 to 60% and their beautiful stonework disappeared from the archeological record. Did Clovis hunters destroy their food sources and become victims of their own success, or did the colder climate of the YD make life untenable for them as it may have for their prey?
The YD cooling has long puzzled scientists. What caused it? Why did it begin and end so suddenly? Answers were so hard to find that one expert despaired, “The origin of the Younger Dryas is likely to remain an enigma for some time to come, perhaps forever.”
Then in 2007, in the prestigious Publications of the National Academy of Sciences (PNAS), physicist Richard Firestone of the Lawrence Berkeley Laboratory and 25 co-authors (henceforth FEA for Firestone et al.) from many specialties and institutions, proposed that at YD time, one or more extraterrestrial objects had exploded in the air over northern North America, destabilizing the last great ice sheet, and launching the YD cooling. The resulting shock wave, impact-induced wildfires and destruction of food resources helped to cause the extinctions and the Clovis decline. The scientists named their idea the “Younger Dryas Impact Hypothesis,” or YDIH.
It did not take long for others to criticize the hypothesis, calling it among other things, a “Frankenstein Monster” and a “long fishing expedition for shreds of support.” They went so far as to imply that FEA had invented an impact hypothesis as a deceptive way of getting grant funding, the same charge that global warming deniers hurl at climate scientists.
Only four years after the PNAS paper appeared, critics went even further, writing a “requiem” for the YDIH and warning that its evident failure, “provides a cautionary tale for researchers, the scientific community, the press, and the broader public,” even comparing it to cold fusion, UFOs, the writings of Deepak Chopra, and other examples of pseudoscience.
Yet despite the years of rejection, the YDIH is alive and growing stronger. Between September 2018 and March 2020, five major peer-reviewed articles on YD sites from four continents provided a plethora of new supporting evidence.
How is it that a scientific hypothesis can weather such seemingly fatal slings and arrows? That is the question we will follow with the peer-reviewed literature as our principal guide. But why go to the trouble? For one thing, in the YDIH we have a twenty-first century example of a hypothesis that appears to violate scientific orthodoxy and is immediately rejected by many. Digging into it helps us understand how scientists deal with controversy. For another, whatever caused the YD, it fundamentally changed (1) the evolutionary development and history of terrestrial animals on Earth; (2) human cultural evolution and history; and (3) climate and ocean history. Without the YD, the Holocene Epoch in which modern humans arose would have begun at least a millennium earlier, with drastic and perhaps unpleasant consequences for humanity, as it might have given global warming a 1,000-year-head-start. Almost everything about the history of the New World would have turned out differently.
It is no exaggeration to say that the YDIH is as important as the now-accepted Alvarez Theory of meteorite impact. Certainly, the YDIH has more direct relevance for we modern humans. If corroborated, it would require scientists in several fields to adopt new paradigms. A successful YDIH would provide a second example that, rather than being isolated in space, the Earth has been and will be at the mercy of the giant roulette wheel of the Cosmos.
PART I:
THE YOUNGER DRYAS IMPACT HYPOTHESIS
1
THE CYCLE OF COSMIC CATASTROPHES
The reading public could have learned of the YD impact hypothesis a year before it appeared in PNAS, when Richard Firestone, Allen West, and Simon Warwick-Smith published The Cycle of Cosmic Catastrophes: How a Stone-Age Comet Changed the Course of World Culture (henceforth, The Cycle).
The website of the publisher, Bear and Company, describes itself as, “One of the largest and oldest publishing houses in the world devoted exclusively to the subjects of spirituality, the occult, ancient mysteries, new science, holistic health, and natural medicine.” Its list of subject areas includes “Astrology, New Age, Paganism, Esoteric & Occult, and New Science and Nature.” The choice of publisher no doubt led many who bought the book to expect something along the lines of Graham Hancock’s best-selling Magicians of the Gods, which posited the onetime existence of an advanced civilization destroyed in a global catastrophe. The book made the New York Times best-seller list in 2015. But in spite of its provenance, The Cycle presents important scientific evidence.
TOPPING AT GAINEY
Although it indulges in some flights of fancy, The Cycle begins with the down-to-earth story of a young Michigander named William Topping, who was seeking a doctorate in archaeology. His state held many Paleo-Indian sites that contained artifacts and the remains of the animals they hunted. As we noted, the cultural artifacts of the Clovis people — their distinctive projectile points and stone tools — had virtually disappeared from the archeological record about 13,000 years ago, as had dozens of species of the large animals they hunted. Whether the two disappearances were connected was a question sure to draw the attention of a budding archeologist, especially one from a state with easily available Clovis sites. Topping thought that accurate dating of the two events might provide a clue.
The principal method of age dating used by archaeologists and anthropologists employs radiocarbon, C-14, an unstable atom of carbon with 6 protons and 8 neutrons instead of the more common 6 or 7 neutrons of C-12 and C-13. In the aftermath of World War II, Willard Libby deduced that radiocarbon had properties that might make it useful for age measurement: and won the Nobel Prize. Libby’s insight was that when cosmic rays — atomic particles traveling through space at many times the speed of sound — strike an atom of nitrogen-14 in the atmosphere, they convert it to an atom of C-14. But C-14 is radioactive, decaying with a half-life of 5,730 ± 40 years. Cosmic ray bombardment continually replenishes the proportion of C-14 in the atmosphere, maintaining it (or so scientists thought) at a constant fraction of total carbon. But some radiocarbon atoms combine with oxygen to form carbon dioxide, which plants capture during photosynthesis and which humans and other animals then ingest. This removes the radiocarbon from the atmospheric carbon cycle, and as it is no longer replenished in its plant or animal host, the proportion of total carbon that is radiocarbon, something that can be measured, steadily declines. Thus, a human bone in an ancient campsite that has exactly half the atmospheric proportion of C-14 is 5,730 years old. If the bone had only one-quarter of the atmospheric proportion, it is 11,460 years old, and so on. The method works back to about 50,000 years ago, before which there is too little C-14 left to measure.
As scientists first began to use radiocarbon, their key assumption was that the proportion of radiocarbon in the atmosphere has remained constant, so that each artifact and bone had started with that known proportion. But as discrepancies began to show up between radiocarbon dates and the known ages of historical artifacts, scientists realized that the proportion of radiocarbon in the atmosphere has not been constant. They got around this problem by measuring the amount of radiocarbon in tree rings, whose age can be determined independently by counting, and using the result to calibrate the curve of radiocarbon dates. Now a scientist who measures a raw radiocarbon date uses the latest calibration curve to adjust it to correspond to ages in calendar years. Confusing to newcomers, scientists may report the result of radiocarbon dating in uncalibrated radiocarbon years, or
in calibrated calendar years. One has to read the fine print, so to speak, before comparing two different radiocarbon dates. In this book, unless otherwise noted or used in direct quotations, I will report radiocarbon dates as calibrated calendar years before 1950 AD, or as scientists denote, “CalYrBP.” This is what I will mean by “years ago.”
The advent of radiocarbon dating, and especially, beginning in the late 1980s, the use of the ultra-sensitive accelerator mass spectrometer to measure the amount of C-14, revolutionized archaeology and anthropology. As we will see, radiocarbon dating will be essential in evaluating the YDIH.
Generally speaking, the further back in time, the larger the correction needed to bring measured radiocarbon dates in line with the calibrated ages. One marked exception occurs at about 13,000 calendar years ago at the onset of the YD. There, contrary to the general trend, a smaller correction suffices. Topping recognized that this discrepancy would be explained if, at the time of the YD, some process had injected fresh, undecayed radiocarbon into the atmosphere, increasing its proportion.