Chapter 21: IMAGES FOR LECTURES

NOTES AND WEB LINKS FOR CHAPTER 21.

The Ice Age

Ice Ages and Climatic Change

The Pleistocene Ice Age

Climate and Geography During the Ice Ages

Ice Sheet Maximum and Ice Sheet Melting

Ice Age Vertebrates

The evolution of the woolly mammoth: a fairly complex story can now be told.

The Overkill Hypothesis (and others)

  • How do you keep mammoth meat fresh? Dump it in the lake! News item on the work of Dan Fisher of the University of Michigan: The research project.
  • Megaherbivores. Text of a 1997 talk by Norman Owen-Smith on the role of megaherbivores in the great extinctions.
  • Environmental change. Text of a 1997 talk by Russell Graham arguing that environmental change was a dominant factor in the great extinctions, at least in North America.
  • Hyperdisease.

  • Impact at the beginning of the Younger Dryas cold period at 12,8000 BP. Just a little while ago, this idea seemed dead. But two new papers (summer 2013) present strong evidence that there was some sort of impact. First, Petaev et al. show that there is a large platinum spike in dust particles in the Greenland ice cap, right at 12,800 BP, the time when the anomalous cold climate of the Younger Dryas begins. The platinum was deposited in perhaps 20 years, in keeping with the lifetime of very fine dust in the stratosphere. The impactor may have been an iridium-poor iron meteorite, the authors say.
    Second, Wittke et al. report analyses of 700 spherules from 18 sites at the Younger Dryas boundary. They infer a relatively large asteroid impact, though their calculations are based on relatively few sites compared with the KT data.
    So we have new studies that are not necessarily compatible with one another. Clearly there is more going on than we had thought, and one or more impacts seem to have occurred. Having established that, we can go on to worry about the nature and mass of the impactor(s), and then what their effect on climate and humans and ecosystems might have been.
    Petaev, M. I. et al. 2013. Large Pt anomaly in the Greenland ice core points to a cataclysm at the onset of Younger Dryas. PNAS 110: 12917-12920
    Wittke, J. H. et al. 2013. Evidence for deposition of 10 million tonnes of impact spherules across four continents 12,800 y ago. PNAS 110: E2088-2097.

    The Americas

    The La Brea Tarpits. Actually, this is redundant, because La Brea means "tar".

    Fighting between bull mastodons: a brilliant study by Dan Fisher, October 2003. Science Daily

    Florida

    South America

    Human Arrival in the Americas

    New thinking in this area suggests that fisherfolk spread along the west coast of the Americas before Clovis people occupied the inner continent. The fisherfolk had little or no effect on the continental ecosystem (though I suspect that they affected coastal ecology dramatically).

    The Yana site in the Siberian Arctic. A report in January 2004 documented humans in the delta of the Yana River, on the shore of the Arctic Ocean in Siberia, about 135 E longitude. But the DATE is 30,000 radiocarbon years ago, more than that in calendar years, in glacial times. This is VERY far north for Homo sapiens at such a date, in such a cold climate. There was abundant large-mammal and bird game, but even so, this is extraordinary. It also puts cold-adapted humans within striking distance of the Bering Strait before the last Glacial Maximum at around 20,000 years. Are these the ancestors of the Clovis invaders of North America, or the mysterious fisher folk that might have been pre-Clovis. We do not know yet. The paper was in Science 303: 52-56, and comment, p. 33. National Geographic News

    Pre-Clovis Arrival and the Coast Route

    Evidence from linguistics:

    The Monte Verde site, in Chile

    New evidence of pre-Clovis people at Cactus Hill, Virginia: an article from the New York Times, April 11, 2000.

    The Meadowcroft site: The Meadowcroft site, which suggests pre-Clovis arrival. Feature article, October 2000.

    Kennewick Man from the Columbia valley. On a separate page.

    Europeans as the First Americans? This is mainly the work of Dennis Stanford of the Smithsonian. It's fair to say most people do not believe it. Here is his suggestion

    Survivors

    Australia

    Island Extinctions

    Madagascar: Text of a 1997 talk in which David Burney summarizes extinctions on Madagascar.

    The dodo Europeans killed off the dodo on Mauritius. Long Wikipedia article, updated to 2013.

    Cuba

    The Bahamas

  • The Bahamian crocodile, and other stories

    Polynesia

    New Zealand

    Experienced Faunas

    Northern Eurasia

    Talk in 1997 by A. J. Stuart on European extinctions.

    Pleistocene Mammals in Russia, at the Russian Paleontological Institution

    The most important local extinctions in the Old World took place in habitats that modern humans were invading in strength for the first time. The large mammals were hunted out of the optimum part of their range, and then the last survivors hung on in the inhospitable (usually northern) parts of their range until newly invading humans or climatic fluctuations killed them off. For example, woolly mammoths, woolly rhinoceroses, and giant deer, along with horses, elk, and reindeer, reinvaded Britain from Europe after the ice sheets began to retreat and birch woodland and parkland spread northward. Mammoths flourished in Britain until 12,800 BP at least, but then human artifacts appeared at 12,000 BP, and the largest animals of the tundra fauna quickly disappeared.

    The giant deer called the Irish elk (not Irish, not an elk) survived until about 7700 years ago, in Siberia.

    Neanderthals and CroMagnons in SW France. Press release, September 23, 2003. This study shows that there were practically no differences in hunting practices between Neanderthals and CroMagnons. The data deal with prey species found in caves that were occupied first by Neanderthals and then by CroMagnons.

    Mammoths

    Frozen mammoths from Siberia.

    Ice Age fashions, and the origin of weaving.
    Olga Soffer argues that evidence of woven textiles revises our view of Cromagnons and their contemporaries in Eastern Europe. And she's probably right: for example, is this the long-sought secret weapon of CroMagnons in competition with Neanderthals?

    My wife says that weaving doesn't mean looms, as the newest story suggests, but that's a minor point. Kids begin weaving without looms, and graduate to them.

    The World Today

    The New World syndrome of diseases

    Gila Indians and diabetes: the grim view from the National Institutes of Health:

    And finally, here are a few links that you should only check if you are feeling strong.

    Wrecking the world's ecosystems

    The reference list for Chapter 21

    Page last updated August 26, 2013.

    Most links checked March 26, 2013.

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