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Mammoths may have died after impact from space

May 20, 2013
Courtesy of the University of Cincinnati
and World Science staff

Di­no­saurs aren’t the only an­i­mals that might have gone ex­tinct af­ter dis­ast­ers such as the crash of a space rock in­to Earth. 

New re­search sug­gests wooly mam­moths, the gi­gantic cousins of mod­ern ele­phants, al­so died out as a re­sult of cli­mate change fol­low­ing a cos­mic im­pact—and that blast may have shocked hu­man popula­t­ions as well.

An electron micro­scope image of a car­bon sphe­rule from She­ri­den Cave. (Pho­to cour­tesy K. Tank­ers­ley)


Wooly mam­moths once shook the earth be­neath their feet, send­ing hu­mans scur­ry­ing. But then some­thing much larg­er shook the Earth it­self, ac­cord­ing to the find­ings. 

Ei­ther a com­et scrap­ing the at­mos­phere or a me­te­or­ite slam­ming in­to the Earth caused glob­al-scale com­bus­tion, scorch­ing the air, melt­ing bed­rock and al­tered the course of Earth’s his­to­ry, ac­cord­ing to re­searcher Ken­neth Tanker­s­ley of the Uni­vers­ity of Cin­cin­nati.

That, he pro­poses, was the last gasp of the Great Ice Age.

“Imag­ine liv­ing in a time when you look out­side and there are ele­phants walk­ing around in Cin­cin­nati,” Tanker­s­ley said. “But by the time you’re at the end of your years, there are no more ele­phants. It hap­pens with­in your life­time.” Tanker­s­ley and col­leagues de­scribe ev­i­dence for the event, es­ti­mat­ed to have oc­curred and to have af­fect­ed at least four con­ti­nents about 12,800 years ago, in the re­search jour­nal Pro­ceed­ings of the Na­tio­n­al Aca­de­my of Sci­en­ces.

“The cli­mate changed rap­idly and pro­found­ly” af­ter the in­ci­dent, he said. “Co­in­cid­ing with this very rap­id glob­al cli­mate change was mass ex­tinctions.”

Tanker­s­ley is an ar­chae­o­log­i­cal ge­ol­o­gist. He uses geolog­i­cal tech­niques, in the field and lab­o­r­a­to­ry, to solve ar­chae­o­log­i­cal ques­tions. He’s found what he said are an­swers to some of those ques­tions in Sheri­den Cave in Wy­an­dot Coun­ty, Ohio. It’s in that spot, 100 feet be­low the sur­face, where Tanker­s­ley has been stu­dy­ing geolog­i­cal lay­ers that date to the “Younger Dry­as” time pe­ri­od, about 13,000 years ago. It’s al­so one ar­ea where mam­moths roamed.

About 12,000 years be­fore that pe­ri­od, the Earth was at the Last Gla­cial Max­i­mum – the peak of the Ice Age. Mil­len­nia passed, and the cli­mate be­gan to warm. Then some­thing hap­pened that caused tem­per­a­tures to sud­denly re­verse course, Tanker­s­ley said, bring­ing about a cen­tu­ry’s worth of near-glacial cli­mate that marked the start of the ge­o­log­ic­ally brief Young­er Dry­as.

There are only about 20 ar­chae­o­log­i­cal sites in the world that date to this time pe­ri­od and only 12 in the Un­ited States, he added. “There aren’t many places on the plan­et where you can ac­tu­ally put your fin­ger on the end of the last ice age, and Sheri­den Cave is one of those,” he said.

Tanker­s­ley found ev­i­dence that some­thing came close enough to Earth to melt rock and pro­duce oth­er in­ter­est­ing ef­fects. Fore­most among the find­ings were car­bon spherules, ti­ny balls of car­bon formed when sub­stances burn at very high tem­per­a­tures. These show char­ac­ter­is­tics that in­di­cate their or­i­gin, wheth­er that’s from burn­ing coal, light­ning strikes, for­est fires or some­thing more ex­treme. Tanker­s­ley said the ones in his study could only have been formed from burn­ing rock.

The spherules al­so were found at 17 oth­er sites across four con­ti­nents – an es­ti­mat­ed 10 mil­lion met­ric tons’ worth – fur­ther sup­port­ing the idea that what­ev­er changed Earth did so on a mas­sive scale, he said.

“Some­thing came close enough to Earth and it was hot enough that it melted rock – that’s what these car­bon spherules are. In or­der to cre­ate this type of ev­i­dence that we see around the world, it was big,” Tanker­s­ley said, con­trast­ing the ef­fects of an event so mas­sive with the 1883 vol­can­ic ex­plo­sion on Kra­ka­toa in In­do­ne­sia. “When Kra­ka­toa blew its stack, Cin­cin­nati had no sum­mer,” he noted. “That’s just one lit­tle vol­ca­no blow­ing its top.”

Tanker­s­ley said while the cos­mic strike had an im­me­di­ate and deadly ef­fect, the long-term side ef­fects were far more dev­as­tat­ing – si­m­i­lar to Kra­ka­to­a’s af­termath but many times worse – mak­ing it un­ique in mod­ern hu­man his­to­ry. Tox­ic gas poi­soned the air and cloud­ed the sky, he ar­gues, caus­ing tem­per­a­tures to plum­met. 

The roil­ing cli­mate would have chal­lenged plant and an­i­mal popula­t­ions, pro­duc­ing what Tanker­s­ley has clas­si­fied as “win­ners” and “losers” of the Young­er Dry­as. He said in­hab­i­tants of this time pe­ri­od had three choices: move to where they could make a si­m­i­lar liv­ing; down­size or ad­just their way of liv­ing to fit the cur­rent sur­round­ings; or die. 

Hu­mans at the time were just as re­source­ful and in­tel­li­gent as we are to­day, he adds, and man­aged to fit among the first two groups. Mam­moths were not so lucky.

“Whether we want to ad­mit it or not, we’re liv­ing right now in a pe­ri­od of very rap­id and pro­found glob­al cli­mate change. We’re al­so liv­ing in a time of mass ex­tinction,” Tanker­s­ley said. “So I would ar­gue that a lot of the lessons for sur­viv­ing cli­mate change are ac­tu­ally in the past.”

Hu­mans of the Young­er Dry­as were hunter-gath­erers. When ca­tas­tro­phe struck, they found news ways and new places to hunt game and gath­er wild plants, he said. Ev­i­dence found in Sheri­den Cave shows that most of the plants and an­i­mals liv­ing there al­so en­dured. Of the 70 spe­cies known to have lived there be­fore the Young­er Dry­as, 68 were found there af­terward. The two that did­n’t make it were the gi­ant bea­ver and the flat-headed pec­ca­ry, a sharp-toothed pig the size of a black bear.

Tanker­s­ley al­so cau­tions that the pos­si­bil­ity of anoth­er mas­sive cos­mic event should not be ig­nored. Like earth­quakes, tsunamis and vol­ca­noes, these types of nat­u­ral dis­as­ters do hap­pen, and as his­to­ry has shown, it can be to dev­as­tat­ing ef­fect.

“One ad­di­tion­al cat­a­stroph­ic change that we of­ten fail to think about – and it’s be­yond our con­trol – is some­thing from out­er space,” Tanker­s­ley said. “It’s a re­minder of how frag­ile we are. Im­ag­ine an ex­plo­sion that hap­pened to­day that went across four con­ti­nents. The hu­man spe­cies would go on. But it would be dif­fer­ent. It would be a game chang­er.”


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Dinosaurs aren’t the only animals that might have gone extinct after the crash of a space rock into Earth. New research suggests wooly mammoths, the gigantic cousins of modern elephants, also died out as a result of climate change following a cosmic impact—and that blast may have shocked human populations as well. Wooly mammoths once shook the earth beneath their feet, sending humans scurrying. But then something much larger shook the Earth itself, according to the findings. Either a comet scraping the atmosphere or a meteorite slamming into the Earth caused global-scale combustion, scorching the air, melting bedrock and altered the course of Earth’s history, according to researcher Kenneth Tankersley of the University of Cincinnati. That, he proposes, was the last gasp of the Ice Age. “Imagine living in a time when you look outside and there are elephants walking around in Cincinnati,” Tankersley said. “But by the time you’re at the end of your years, there are no more elephants. It happens within your lifetime.” Tankersley and colleagues describe evidence for the event, estimated to have occurred and to have affected at least four continents about 12,800 years ago, in the research journal pnas. “The climate changed rapidly and profoundly” after the incident, he said. “Coinciding with this very rapid global climate change was mass extinctions.” Tankersley is an archaeological geologist. He uses geological techniques, in the field and laboratory, to solve archaeological questions. He’s found what he said are answers to some of those questions in Sheriden Cave in Wyandot County, Ohio. It’s in that spot, 100 feet below the surface, where Tankersley has been studying geological layers that date to the “Younger Dryas” time period, about 13,000 years ago. It’s also one area where mammoths roamed. About 12,000 years before that period, the Earth was at the Last Glacial Maximum – the peak of the Ice Age. Millennia passed, and the climate began to warm. Then something happened that caused temperatures to suddenly reverse course, Tankersley said, bringing about a century’s worth of near-glacial climate that marked the start of the geologically brief Younger Dryas. There are only about 20 archaeological sites in the world that date to this time period and only 12 in the United States, he added. “There aren’t many places on the planet where you can actually put your finger on the end of the last ice age, and Sheriden Cave is one of those,” he said. Tankersley found evidence that something came close enough to Earth to melt rock and produce other interesting effects. Foremost among the findings were carbon spherules, tiny bits of carbon formed when substances burn at very high temperatures. These exhibit characteristics that indicate their origin, whether that’s from burning coal, lightning strikes, forest fires or something more extreme. Tankersley said the ones in his study could only have been formed from burning rock. The spherules also were found at 17 other sites across four continents – an estimated 10 million metric tons’ worth – further supporting the idea that whatever changed Earth did so on a massive scale, he said. “Something came close enough to Earth and it was hot enough that it melted rock – that’s what these carbon spherules are. In order to create this type of evidence that we see around the world, it was big,” Tankersley said, contrasting the effects of an event so massive with the 1883 volcanic explosion on Krakatoa in Indonesia. “When Krakatoa blew its stack, Cincinnati had no summer. Imagine winter all year-round. That’s just one little volcano blowing its top.” Tankersley said while the cosmic strike had an immediate and deadly effect, the long-term side effects were far more devastating – similar to Krakatoa’s aftermath but many times worse – making it unique in modern human history. In the cataclysm’s wake, toxic gas poisoned the air and clouded the sky, he argues, causing temperatures to plummet. The roiling climate challenged plant and animal populations, producing what Tankersley has classified as “winners” and “losers” of the Younger Dryas. He said inhabitants of this time period had three choices: move to where they could make a similar living; downsize or adjust their way of living to fit the current surroundings; or die. Humans at the time were just as resourceful and intelligent as we are today, he adds, and managed to fit among the first two groups. Mammoths were not so lucky. “Whether we want to admit it or not, we’re living right now in a period of very rapid and profound global climate change. We’re also living in a time of mass extinction,” Tankersley said. “So I would argue that a lot of the lessons for surviving climate change are actually in the past.” Humans of the Younger Dryas were hunter-gatherers. When catastrophe struck, they found news ways and new places to hunt game and gather wild plants, he said. Evidence found in Sheriden Cave shows that most of the plants and animals living there also endured. Of the 70 species known to have lived there before the Younger Dryas, 68 were found there afterward. The two that didn’t make it were the giant beaver and the flat-headed peccary, a sharp-toothed pig the size of a black bear. Tankersley also cautions that the possibility of another massive cosmic event should not be ignored. Like earthquakes, tsunamis and volcanoes, these types of natural disasters do happen, and as history has shown, it can be to devastating effect. “One additional catastrophic change that we often fail to think about – and it’s beyond our control – is something from outer space,” Tankersley said. “It’s a reminder of how fragile we are. Imagine an explosion that happened today that went across four continents. The human species would go on. But it would be different. It would be a game changer.”