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 Exceptions = mesofauna (such as some species of rodent and rabbit) that also went extinct. Many species also didn’t die out, but went through a genetic bottleneck (grey wolves) Emphasize that this is not a “tragedy” but a fundamentally different ecology that went through a radical change. 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! = Megafauna are important because the occupy a somewhat precarious niche space. They are large herbivores that are fewer in number, have a slow reproduction rate, and require lots of calories to survive, making them the preeminent taxa to become extinct in an ecosystem. Like the canary in a coal mine, megafauna act as an early warning system for

ANTARCTIC REGLACIATION MEGAFAUNAL EXTINCTION Cenozoic ANTARCTIC GLACIATION ANTARCTIC REGLACIATION MEGAFAUNAL EXTINCTION THERMAL MAXIMUM ANTARCTIC THAWING 65 Ma 58 37 24 5 2 11,500 yrs Paleocene Eocene Oligocene Miocene Pliocene Pleistocene Holocene

Human Influence 16 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) 15 - 13 Ka

Other Predators Non- human Predators Human Predation Non-human predators forced to hunt less calorically efficient prey Prey population controlled by predators Abundant resources and habitat space Non- human Predators Prey population numbers 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