Johnson suggests the fungus research is superb evidence for when the decline began, but it is not as good at confirming exactly when the extinction was completed, especially over larger areas where sparse populations might have persisted. The DNA finds, on the other hand, can detect late survivors, he says, “maybe very close to the actual time that the last individuals were alive, at least in Alaska.” The bones analyzed from the period roughly in between show that the extinction process afflicted many species simultaneously. Those fossils came from the contiguous U.S., which back then was separated from Alaska by the massive Laurentide and Cordilleran ice sheets and so, Faith notes, could explain why the pattern of extinction differed up there.

So what caused the decline? The jury’s still out, says Willerslev’s collaborator Ross MacPhee of the American Museum of Natural History in New York City. Johnson notes that archaeologists are turning up evidence of humans in the New World before Clovis, and he suggests they overhunted the megafauna. The beautifully crafted fluted spear points linked with the Clovis might reflect strategies that developed once the giants became rare and harder to hunt, Johnson adds.

Even if scientists cannot definitively finger the killer, research into the megafauna disappearance “is directly relevant today because we are in the middle of a mass extinction and one for which we know the cause—us,” Gill says. “Large animals are among the most threatened today,” she points out, and no one wants Africa to follow the ancient experience of the Americas.

This article was originally published with the title Lost Giants.

5 Comments

1. 1. Rustning 09:52 AM 1/30/10

   There is little doubt given the slaughter sites already documented that incoming "native americans" were the alien intrusion that tipped the scales to extinction.

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2. 2. jtdwyer in reply to Rustning 11:06 AM 2/2/10

   It seems to me that discovery of preserved slaughter sites establishes the presence of humans coterminous with at least some species of megafauna, but does not preclude any other cause of extinction. Of course, no assessment can be made from your breif comment.
   
   Correlation does not establish causation. It often amazes me how the existence of preserved evidence is interpreted to be a representative population sampling. Evidential preservation often occurs only in very specific circumstances under very special conditions. The absence of preserved evidence does not establish that events or conditions did not occur, except in the cases where preservation is highly probable. The best example of this that I can recall is the paleontologist who asked: “…if a meteorite suddenly destroyed all the dinosaurs, where are all the fossils?” Apparently, this eminent scientist did not realize that, for example, vaporization is not a condition favorable to preservation.

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3. 3. katesisco 01:09 PM 2/12/10

   More and more evidence is accumulating that a significant event happened around 10,000 ya. And another event has been identified as around 5,000 ya. Harappa and the recently discovered site in Mesopotamia indicate large population centers devastated. Most interesting is the 'large population'.

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4. 4. cofu 04:47 AM 2/13/10

   The dynamic model of the globe a site www.mammoths.narod.ru - has proved what events occured on a planet in stages II - IV, these events
   are proved by traces of processes on continents, and also the separate information which appears in scientific publications; separation
   the scientific organizations, separation of scientists, absence the uniform coordination Center on a planet - does not allow to have for given time of this civilization a real picture of changes on continents in recent times - not abstractly, and is concrete on stages; if such Center
   already there is it even worse

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5. 5. Extremophile in reply to Rustning 02:46 PM 2/13/10

   Rustning,
   
   sorry, big doubt is far more appropriate. A small group of people, more unlikely than likely to be big hunters, killed all the big game of an entire continent? Think twice.
   
   Your theory cannot be verified, I believe, it can't even be validated.
   
   Even if men came before or during the extinction of mammoths and other big animals, this would not prove that they have done it.
   
   There is no smoking gun. There is in fact no gun at all.

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