Humans and the Pleistocene Megafaunal Extinction

Kelsey T. Stilson

Cultural and Climate Revolution

• Migrations change both humans and the ecosystem.

Shared Space

Humans

Ecosystem

Climate

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!

=

Cenozoic

Paleocene Eocene Oligocene Miocene Pliocene Pleistocene Holocene

65 Ma 58 37 24 5 2 11,500 yrs

THERMAL MAXIMUM

MEGAFAUNAL EXTINCTION

ANTARCTIC GLACIATION

ANTARCTIC THAWING

ANTARCTIC REGLACIATION

Human Influence

• 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)

16 Ka

15 - 13 Ka

Other Predators

Non- human Predators

Prey population numbers controlled by Predators

Abundant resources and habitat space

Human Predation

Non-human predators forced to hunt less calorically efficient prey

Prey population controlled by predators

Abundant resources and habitat 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