A fungus found within ancient mammoth dung is providing scientists with clues about how the large ancient mammals collectively known as megafauna went extinct. The fungus, Sporormiella, produces spores in the dung of large herbivores. These are then preserved in the layers of mud and can provide an index of the number of these animals, or megafauna, that roamed the environment at a particular time [BBC News]. For a new study, researcher Jacquelyn Gill collected and analyzed spores in sediment samples from an Indiana lake and several sites in New York.
From Gill’s analysis, published in the journal Science, she concluded that North American megafauna began a slow decline around 15,000 years ago and vanished about 1,000 years later. The data suggests megafauna started going extinct much earlier than previously though, which basically wipes out two theories of their extinction.
There are several theories surrounding the extinction of North American megafuana, but there are a lot more questions than answers. Much of the uncertainty surrounding the extinction of the North American megafauna, which includes mastadons, saber-tooth tigers and giant ground sloths, is due to a scarcity of evidence and difficulty pinning down the timing of events. Several major events occurred around the same time the animals disappeared: Major environmental upheaval associated with the end of the Ice Age; an asteroid explosion over North America; and the arrival of man [Wired.com]. But the new data points to an extinction culprit other than an asteroid or comet impact, because the impact is believed to have occurred long after the megafauna began their decline.
If humans were responsible for the extinction, it would have to be settlers that came along before the Clovis people, which is another debate in itself. The Clovis culture is thought to have been the first civilization to take hold in North America around 13,300 years ago–after the bulk of the megafauna extinctions, according to the new analysis. But some researchers believe that earlier settlers walked the land before the Clovis people, and could have hunted the mastodons and mammoths. The new study adds crucial info to the fossil record, but it is likely to kindle, rather than quench, the debate over megafauna extinction.
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Image: Barry Roal Carlsen, University of Wisconsin-Madison
November 20th, 2009 at 9:23 am
It’s virtually always some change in the environment which drives evolution and extinction, at least until humans developed the technology to destroy entire species.
I can’t believe that a relative few hunter/gatherers had a key role in the extinction of various species of mega-fauna, unless those species were already at a dangerously low breeding population.
I still think we must look to environmental changes driven by climate shifts as the basic culprit here. These climate changes are cyclical in nature, and are somewhat predictable as well. The larger the animal the more food it needs and the more likely it is to become extinct during geologically rapid changes in global or local climates. Of course, the larger and more specialized preditors quickly follow suit. This has been the pattern for hundreds of millions of years, until recently when we humans have developed large populations and profound technologies.
November 20th, 2009 at 10:19 am
The only thing that changed in North America was the introduction of man. Ice ages came and went, and the fauna flourished. It collapsed when a relentless predator invaded all spheres of the landscape, one that killed carnivores, herbivores, and omnivores with equal disregard. Native American culture shows a disconnect between the earliest cultures, Mound Builders, Anasazi, etc. and the later cultures. This disconnect is attributable to the need for redefinition as a culture that enjoyed plenty, to one based on scarcity. This would be consistent with the die off. I think the title of this article is misleading and ignores the findings in the report in exchange for a vindicating headline. No one holds anyone responsible in a civil manner for killing off ice age mammals, but facts are facts.
November 20th, 2009 at 12:23 pm
Perhaps the extinction of megafauna like the great cats was what made successful colonization by man possible?
November 20th, 2009 at 2:25 pm
Fact is, there were simply not enough of these early humans to wipe out various species of mega-fauna over the entire continent, or even a major portion of it. Let’s not forget the demise of the Clovis culture because of some climate changing. Small groups of hunter/gatherers, and these early peoples existing in close-knit family units, just could not destroy large populations of widely spread animals. A mastodon or mammoth is no easy mark for the best of hunters, and elephants even posed danger and difficulty for modern hunters armed with high-powered fireams.
Ice ages did come and go, but a lot of various fauna went extinct nonetheless. This was without any humans around at all.
November 22nd, 2009 at 10:18 am
Mega fauna had a much longer gestation, followed by a single offspring, dependent on its parent for much longer than mammals today. It doesn’t take much to disrupt a population. Its hard to be dismissive of mans role when his spear points are found in Mammoth bones. Man also spread across this continent in just a few hundred years- and he wasn’t eating tofu..
November 23rd, 2009 at 7:55 pm
Why can’t we just compromise and say that it was really just a combination of all of these factors? ;)
November 23rd, 2009 at 8:50 pm
I hold with “Bystander,” but I would still lay a heavy burden on human hunters. History and archaeology have repeatedly shown that humans with primitive weapons have killed off many species, e.g. the elephant birds of Madagascar and the moas of New Zealand.
November 30th, 2009 at 2:35 pm
It would be a lot easier for man to kill off a species in a relatively small geographical area like both Madagascar and New Zealand than such an incredibly large land mass like North America. I tend to agree more with the environmental factors than the relatively sparse hunter/gatherer in such a varied geographical range like North America. Please don’t forget that it take s about 5-7 days to drive across Canada – and that is with modern modes of transportation and highway systems. There would be more likely to be pockets of survival of a fauna species if it was mainly man doing the damage in this case. When it takes a lot of ingenuity and many hunters to take down a single Mastadon the numbers just don’t pan out for man being the major factor in the mega fauna extinction in North America.
November 30th, 2009 at 3:18 pm
There are many reasons why a fauna might become extinct. Lack of food could be one, due to disaster or climate change. The great pandas of China are expected to die off because the bamboos that make up their principal diet are disappearing due to development. (Flora disappears too). A great disaster isn’t necessary. My branch of my family is disappearing because my ex-wife and I chose not to have children, and I am now in my 80’s. Some animals are known to make similar choices when faced with stress.
December 1st, 2009 at 12:55 am
Too many typos, which make reading ambiguous !
December 1st, 2009 at 5:26 am
Early hunters had a habit of killing moe than they needed. Bison in America, for example, were driven over cliffs. While a lot of butchering then commenced, and creation of hides, many animals died unnecessarily. The big animals reproduced slowly. Any ‘herd’ of mastodons drven over a cliff could have disastrous consequences. The idea that hunters surrounded these animals and killed them one-by-one, as Clovis artifacts indicate happened a few times, does not preclude the fact that a herd of mastodons driven over a cliff by using torches, etc. to spook them would wipe them out much more quickly than the practice as used on bison. Cooperating human hunters can do tremendous damage in a short time to large herbivores. And even one spear wound, as we know from watching Animal Planet and the death of Enid, can be fatal.
December 2nd, 2009 at 12:47 pm
Michael, in comment 1, says, “It’s virtually always some change in the environment which drives evolution and extinction, at least until humans developed the technology to destroy entire species.” Keep in mind that an influx of humans _is_ a change in the environment. Especially if their hunting practices make a sizable dent in the rate of reproduction of existing species. You don’t have to take out a lot of megafauna to shift the net growth rate from 0 (stable), to minus.