Transcript 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!
=
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