Download Humans and the North American Pleistocene

Humans and the Pleistocene Megafaunal Extinction

Kelsey T. Stilson

Cultural and Climate Revolution • Migrations change both humans and the ecosystem. Humans Ecosystem

Climate

Shared Space

Novel System

Stepped Global Extinction Events

Barnosky, AD; Koch, PL; Feranec, RS; Wing, SL; Shabel, AB. Assessing the causes of late Pleistocene extinctions on the continents. Science (New York, N.Y.) 2004 Oct 1; 306(5693): 70-5.

North America

• American Horse, Mammoths, Mastodons, Lions, Cheetahs, Giant Ground Sloths, Camels, Glyptodonts, Indricotheres, Saber-toothed cat, Dire wolves, Peccaries, Tapirs… • Exceptions

Why do we look at Megafauna? • Megafauna = 44+ kg (100 lbs) • Early indicators of climate change!

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Cenozoic ANTARCTIC REGLACIATION

ANTARCTIC GLACIATION THERMAL MAXIMUM

65 Ma

58

Paleocene

MEGAFAUNAL EXTINCTION

ANTARCTIC THAWING

37 Eocene

24 Oligocene

5 Miocene

2 Pliocene

11,500 yrs Pleistocene

Holocene

Human Influence 16 Ka

15 - 13 Ka

• Overkill (Blitzkreig) Hypothesis: Paleoindians hunted the megafauna to extinction (Paul Martin)

• Timing is right, but the evidence is limited for complete human responsibility. Too few taxa Few kill sites • ‘Sitzkrieg’ Hypothesis: other ways humans alter the environment (Jared Diamond)

Other Predators Human Predation

Non- human Predators Non-human predators forced to hunt less calorically efficient prey

Prey population numbers controlled by Predators Prey population controlled by predators

Abundant resources and Abundant resources and habitat habitat space space

Hyperdisease • Brought over by humans or dogs with the migration over beringia. • Extremely deadly • This would require the virus or bacteria to ‘jump’ between different Orders, something that has never been observed in modern biology.

Bolide Impact

Guthrie, Dale R. New carbon dates link climatic change with human colonization and Pleistocene extinctions. Nature Vo. 441. Issue 7090 p.207

Implications for the Future Overkill, Over-chill, Over-ill… • Humans today affect the ecosystem, how far back does this go? • Depends on culture • How will we change as we change our environment?

Thank You! Special thanks to Professor Mark Carey, Professor Sam Hopkins, and Dr. Edward Davis