Many have adopted the view that both hunting and climate change contributed to the extinction. One major review of the “State of the Debate,” published in 2006 (three years after the Grayson and Meltzer Requiem), suggests that,
Humans precipitated extinction in many parts of the globe through combined direct (hunting) and perhaps indirect (competition, habitat alteration) impacts, but that the timing and geography of extinction might have been different and the worldwide magnitude less, had not climatic change coincided with human impacts in many places.
But this may be conflating two failed theories into one.
TESTING THE YDIH
For the megafauna, unlike the Fall of Clovis, we have fossil bones as evidence. We know that, as Vance Haynes reported, “No skeleton of extinct megafauna has ever been found in or above the black mat, only below it.” We also know that fossil remains are in direct contact with the black mat. Again, let us turn to Haynes: “The American horse, dire wolf, saber-toothed tiger, American camel, mammoth, and mastodon, all of them disappeared in an instant before the black mat formed. When we dig up their bones today, the black mat covers them like a blanket.” This is well illustrated in the annotated photo below.
FIGURE 21:
The YDB at Murray Springs, showing ten animals whose bones are found directly touching the Black Mat
The presence of these fossils right up to the black mat contrasts with aspects of dinosaur extinction and the Alvarez Theory. Dinosaur fossils are extremely rare, so that the chances of finding one below the KTB is unlikely. Rather, the last known occurrence of a particular dinosaur species will likely be found some distance below the boundary. Collectively, this gives the false impression that the extinction was gradual, not sudden as the Alvarez Theory requires. But this is an artifact of the unlikelihood of ever finding the youngest specimen (the “Signor-Lipps Effect”). With the YDB, we do not have this concern, because at Murray Springs, the abundant fossils lie right at the boundary, or are even part of the boundary, with the black mat draped over them like a funereal shroud. Above the mat, they are never seen again.
Thus the megafaunal evidence is entirely consistent with the YDIH.
I will conclude these many chapters on the evidence by paraphrasing what John Shea said about the Solutrean hypothesis, “The extraterrestrial theory deserves a second look. If it is wrong, it should be more convincingly wrong. If it is right, we may need to rethink long-held notions.”
Scientists may even need to shift some paradigms.
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PARADIGM SHIFTS
The Younger Dryas brought such profound change that scientists use its termination to divide the Quaternary Period into the older Pleistocene Epoch and the younger Holocene — in which we live. But for the first time in earth history, human activities are speeding up changes that formerly occurred only on geologic timescales. Just three centuries past the Industrial Revolution, humans have burned enormous quantities of fossil fuels that took hundreds of millions of years to accumulate, adding enough CO2 to the atmosphere to change global temperature, endanger human civilization, and even threaten humanity itself.
Some scientists believe that the changes humans are wreaking on a planetary scale justify the recognition of a third Quaternary Epoch: the Anthropocene. Perhaps they are right, for to return CO2 to pre-industrial levels may take tens of thousands of years, an eternity on our human timescale and a duration that approaches those of geological events like the ice ages. On our present trajectory, this will be the poisonous fruit of climate denial, the true cost of the oil age and of human failure. But one day, in an eyeblink of geological time, the Anthropocene will end and climate will once again bow to the clockwork domination of its astronomical pacemaker. But will anyone be around to notice?
Geologists have chosen the boundaries that define the eras, periods, and epochs of the geological timescale because they represent times of unusual change, particularly of life forms. The YD certainly qualifies as one of those times. If an ET event triggered the YD and the changes it brought, as the evidence suggests it did, thought in several scientific disciplines will have to change as well. The following possibilities come to mind.
THE IMPACT PARADIGM
When Richard Kerr interviewed impact experts about the YDIH in the spring of 2008, he found them already outspoken in rejection. They could have regarded the microspherule and nanodiamond peaks as evidence of impact, but soon SEA and others would report that those peaks do not exist, sending opponents down the other fork in the road, the route to “irreproducible.”
But as we have seen, the microspherule and nanodiamond peaks have been replicated at dozens of YDB sites. These must now be regarded as plausible impact indicators, as must the new markers found at sites such as Pilauco and at Abu Hureyra: platinum, palladium, gold, high-temperature Fe-rich and Cr-rich spherules, native iron grains, meltglass, and more.
Should the Hiawatha Crater date to the YDB, it will raise almost as many interesting questions for impact science as it answers. What was the nature of the impactor? How could the impact have had such distant effects as to cross the Equator and reach at least 40°S? Why have no shocked minerals been found anywhere at the YDB? Why is there no trace of the impact in the nearby ice cores? How many of such questions can be answered by an impact onto the thick Greenland ice sheet? Are these effects at the YDB “one-off,” or might there have been other similar impacts in earth history and how would scientists recognize them?
ANTHROPOLOGY
As we have seen, the YDB event changed human cultural evolution and history. Scientists have found Clovis or Clovis-like points not only across much of North America, but at sites in Mexico, Central America, and Venezuela. Here was a pervasive and commanding culture whose cultural toolkit nevertheless disappeared from the record virtually instantaneously. Instead of one successor culture, many diverse types arose, each with its own distinctive stonework. This calls to mind the Fall of Rome, after which in the Middle Ages, several European cultures cognizant of Roman culture arose to replace the dominance of Rome. Now archeologists and anthropologists will have to factor into their thinking the very real likelihood that an ET event significantly contributed to the fall of Clovis and the loss of its distinctive stone points.
The beauty and artistry of the Clovis stonework went well beyond what would have been necessary for a functional hunting weapon. Looking at these artifacts in a museum collection today, one can easily believe that the Clovis took the trouble because to create art is an innate characteristic of our species.
The Clovis were far from the only pre-historic culture to make art. The Solutreans, whom we met as possible pre-Clovis colonizers of North America, produced beautiful relief sculptures of horses and bison, as well as pictographs and friezes. Their successors, the Magdalenians, were the “cave painters” of Lascaux in the Dordogne region of France. The archeologists who discovered their artwork named their culture the “Age of the Reindeer.” Others later renamed it for a rock shelter at what became the type site at “La Madeleine” in the Dordogne.
Magdalenian art included not only the multi-colored cave murals, but engraving, sculpture, jewelry, ivory carvings, and much more. Like the Clovis, they went beyond necessity to turn their tools into art, as witness the “Lortet Reindeer,” an implement made from an antler and decorated with engraved depictions of fish and reindeer.
Professor Michael Jochim has noted that “The Younger Dryas in Europe has long been recognized as a period of significant environmental and cultural changes.” One of those changes was a decline in the quality of Magdalenian art as the Mesolithic Era, the middle period of the Stone Age, began. The Magdalenians gave way to the Azilian culture, whose tools and artwork were pale shadows of their predecessors, just as the Folsom points never matched the beauty of those of Clovis.
One team of scientists, reflecting on the disappearance of such art forms during the YD, wrote, “There is a growing consensus that the influence of these changes in prehis
toric humans offers a point of reflection for current humanity, also confronting a rapid climate change.” One result of such reflection is to realize that societies under extreme stress no longer have time for art. Of course, individual artists continue to work and may even use stressful events as inspiration, as Picasso did with the German bombing of Guernica during the Spanish Civil War. But art no longer imbues an entire society, one of the many finer and distinctively human creations lost when the quest for survival takes over.
Unlike the dinosaur killer, the YD impactor may have been a killer of human cultures, such as the Magdalenian. On our present foolhardy trajectory, art, education, and science itself may be among the victims of our self-induced Anthropocene.
As we have seen, the rise of agriculture in Western Asia began with the YD. The Abu Hureyra site contains irrefutable evidence of a nearby impact at the same time. If cosmic impact was at least partly responsible for the inception of agriculture at Abu Hureyra and at other sites in western Asia, archeologists will have to take that fact into account as well.
MEGAFAUNA
We have discussed the loss of the Pleistocene megafauna of North America and its possible causes, noting that both the overkill and climate change hypotheses have serious weaknesses. Similar extinctions occurred at many other times and places during the Pleistocene. As one review article noted,
Fifty thousand years ago, continents were populated with more than 150 genera of megafauna (animals >44 kg). By 10,000 years ago, at least 97 of those genera were gone.
The debate over climate change vs. human hunters that we have reviewed among North American scientists has been repeated around the world. In some cases, as with the Moa in New Zealand, extinctions can be traced directly to humans, helping to keep the overkill hypothesis alive in other venues. But if an ET event contributed to the megafaunal extinction in North America, or acted as a trigger, archeologists will have to adjust their thinking to consider that the YD extinction was a unique event that cannot be used as a guide for Pleistocene extinctions at other times and places.
CLIMATE CHANGE
By the end of the 1980s, new evidence had come to light from ice cores and other sources showing that the climate can change abruptly — on a scale of decades and even years. This is no surprise to readers of this book, but at the time, coming as it did with the recognition of global warming, “abrupt climate change” became something else that scientists and the public needed to learn more about. If the climate can change rapidly on its own, how fast will it change when we prod it?
Reflecting this growing concern, in 2002 the National Research Council published, “Abrupt Climate Change: Inevitable Surprises,” defining the term to mean a change that “takes place so rapidly and unexpectedly that human or natural systems have difficulty adapting to it.” The report went on to state,
The quintessential abrupt climate change was the end of the Younger Dryas interval about 11,500 years ago, when hemispheric to global climate shifted dramatically, in many regions by about one-third to one-half the difference between ice-age and modern conditions, with much of the change occurring over a few years.
But if a cosmic event caused the YD, then it is not the quintessential example of abrupt climate change after all.
ICE SHEET BREAKUP AND OCEANIC CIRCULATION
Consider the timing of four major YD events: (1) the great plumbing shift that cut off water flowing to the Gulf of Mexico and diverted it into the North Atlantic; (2) the collapse of Lake Agassiz; (3) the draining of its Western European counterpart, the giant Baltic Ice Lake; and (4) the breakup of the Greenland ice sheet margin at or close to the YD onset.
Recall that Lake Agassiz, the giant ice-age lake that straddled several Canadian provinces (see Figure 17) and parts of the northern U.S., had drained to the south, down the Mississippi and into the Gulf of Mexico. Then as the Laurentide ice sheet melted and its front retreated northward, ice dams disappeared, new outlet channels opened, and the drainage suddenly switched. Lake Agassiz now discharged eastward through the St. Lawrence system and into the North Atlantic, and northward through the Mackenzie River system and into the Arctic Ocean. The best estimate of the cut-off of the fresh meltwater into the Gulf of Mexico is 12,940 ± 170 years ago, and, independently, the beginning of the outburst from Lake Agassiz dates to 12,940 ± 150 years ago.
Meanwhile, far across the Atlantic stood the Baltic Ice Lake, a huge body of freshwater that had formed in front of the northward-retreating Scandinavian ice sheet, where today we find the Baltic Sea. The Baltic Ice Lake began to collapse precisely at the YD onset. Finally, at the same time, the margins of the Greenland ice sheet began to break up and collapse.
Using conventional thinking, it is hard to explain why these four events, separated by thousands of miles and each with its own climate, should all have occurred at nearly the same time. The YDIH can explain them.
Some of these potential paradigm shifts may in time take place, others may not, and still others may emerge. We know that great scientific changes are best recognized with the advantage of hindsight. But if scientists are willing to “live with provisionality,” they can use the Younger Dryas Impact Hypothesis to learn more about our planet and our place upon it.
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WHAT IF THERE HAD BEEN NO YOUNGER DRYAS?
THE 1000-YEAR HEAD START
The Younger Dryas changed ocean circulation, global climate, human cultural evolution and history, the evolutionary development of terrestrial animals, and more. If the impact hypothesis is correct, as with the dinosaur killer, a random, unpredictable event launched the YD. Alter the history of the solar system an infinitesimal amount, and the KT or YD impacts might well not have occurred, though others would have. For an event of such moment as the YD, and especially one with direct and historic effects on our modern world, it is only natural to ask which of those changes might not have happened without an ET event at the YDB, and what might have happened instead. Here we leave strict science and enter the realm of informed speculation.
Part of the difficulty in explaining the long-standing mystery of the YD in the Northern Hemisphere has been that the astronomical alignments that control Earth’s climate were going in the wrong direction to produce cooling. At the onset of the YD about 13,000 years ago, the Earth was undergoing warming that would have continued until about 10,000 years ago, more than a millennium after the YD ended. Thus the YD began suddenly, continued for 1,300 years, and ended suddenly, all the while thumbing its nose at our astronomical timekeeper.
Without the trigger of the ET event, the immense draining of Lake Agassiz and other proglacial lakes that the warming was causing, instead of happening simultaneously, would have been spread out over a longer period. Instead of a single great plumbing shift, there might have been many smaller, asynchronous leaks. Then, without that single, large pulse of freshwater onto the North Atlantic Ocean, the oceanic conveyor might have weakened but not shut down entirely. Instead of the YD cooling, warming might have continued unabated. This line of thought suggests that without an ET event, there would have been no YD nor any of the multitude of changes that it brought.
Imagine yourself a geologist in the future, trying to interpret the geological record to understand the changes that preceded the deadly Anthropocene. Without the ET event and the rapid cooling it caused, the YD might not have happened at all, or had much smaller effects. Would it have stood out in the geological record from the two-dozen similar Pleistocene temperature oscillations? If not, future geologists would likely place the Pleistocene-Holocene boundary at the termination of the last ice age, about 14,500 years ago. Without the YD cooling then, the warming would have continued and the Holocene would have had a 1,000-year head start. When we think of the changes that have occurred in every aspect of human society in just the last 200 years, the mind boggles to imagine what such a running start might have meant for humanity by the twentieth century. The beneficial advances in medicine, science, and technology that have marked the
last 200 years might have come centuries earlier. Then comes the sobering realization that so might have an Industrial Revolution and its apparently inevitable product: global warming.
HUMAN CULTURE
Without the return to glacial temperatures in the Northern Hemisphere brought about by the YD, the large ice sheets would have melted faster and sea level would have risen faster, possibly blocking the migration route down the Pacific Coast. But the ice-free corridor would have opened earlier, giving the pre-Clovis people a head start into the rest of the hemisphere. Millennia later, without the setback of the YD, instead of disappearing, Clovis might have continued and expanded as the dominant culture in the Western Hemisphere and lasted for millennia.
Regardless of when the first people arrived in North America, they reached the southern tip of South America in a remarkably short time — if by the ice-free corridor, in only 1,000 years. Just imagine what they could have accomplished had they possessed domesticated horses and camels for transportation and the two of them plus the other large mammals for food.
This line of thinking calls to mind the question that Jared Diamond posed in his prize-winning Guns, Germs, and Steel. To paraphrase: “Why did Native Americans not turn out to be at least the equal in invention and accomplishment of the Europeans who arrived on their shores?” Could part of the answer be, “Because of the setback of the YD and its aftershocks in the Western Hemisphere?”
After all, from the onset of the YD at about 12,800 years ago to arrival in the Western Hemisphere of mounted Conquistadors in the 1500s, over 11,000 years passed. Had there been no YD, had Clovis continued and flourished, there is no reason to believe that they and their successors would have proven any less intelligent and inventive than Europeans. And in all those millennia, might not the early Americans have developed immunity to some of the genocidal germs that the Europeans would bring with them? Might not they have invented gunpowder, learned to sail out of sight of land in wind-powered vessels, and reached Europe?
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