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Transcript
Paleoanthropology
Paleoanthropology
• The study of human and primate evolution.
• The study of human ancestors.
• The study of ancient populations.
• In order to determine how and when this
evolution happens, we will need to look at
dating methods used in archaeology.
Dating Methods
• Stratigraphy
• Carbon-14 dating
• Dendrochronology
Relative Dating: comparative method which
determines the sequence in time by showing
which specimen is older, but not an exact
date.
Chronometric Dating: determines an “exact”
date for a specimen or site.
Stratigraphy
• Is a relative dating tool
• The older something is, the
deeper it is in the ground.
• Situations where using this
method might be difficult?
Dendrochronology
• Chronometric dating method
• Trees tend to create one growth ring per
year. By counting the rings on the tree, we
know how old it is.
• Width of the ring depends on the moisture
in the air during the year it formed. Ex:
thicker rings = lots of rainfall.
Carbon-14
• Chronometric method
• Is based on the “half-life” of carbon-14 that can be
applied to organic remains.
• 12C is absorbed through plants, cosmic radiation
causes 14C.
• When an organism dies the 14C begins to decay,
the rate of decay (5,730 years for ½) is measured to
determine how old the remains are.
• http://www.youtube.com/watch?v=UTMOXxS
Oy5E
Other Dating Methods
• Thermoluminescence: Radiometric decay;
materials which were heated in the past and
that release stored energy as light once
reheated.
• Obsidian Hydration Dating
• Biostratigraphy: dating a site based on
presence of certain fossil species.
Geologic Time
• The earth is 4.6 BILLION
years old.
• The first primates evolved
about 50 million years ago.
• The first hominins evolved
about 6 million years ago.
• Geologically speaking,
these last two dates are
relatively recent events.
Carl Sagan’s Cosmic Calendar
• Big bang: January 1
• Origin of the Milky Way:
May 1
• Origin of the solar system:
September 9
• Formation of Earth:
September 14
• Origin of life on earth: ~
September 25
• Oldest fossils (bacteria and
blue-green algae: October
9
• First cells with nuclei:
November 15th
Carl Sagan’s Cosmic Calendar
Geologic Time
• Eons: a major subdivision of geologic time.
The history of earth is divided into 4 eons.
• Era: a subdivision of an eon.
• Period: a subdivision of an era.
• Epoch: a subdivision of a period.
Geologic Time
• Precambrian: contains 3 of the 4 eons. 90%
of the earth’s history.
– Hadean eon: 4,300-3,800 Ma. Origin of the earth
prior to any fossil evidence of life.
– Archean eon: 3,800-2,500 Ma. Fossils of first
forms of life. Single-celled organisms.
– Proterozoic eon: 2,500-542 Ma. Oxygen in the
atmosphere, first multicelled organisms.
Geologic Time
• Phanerozoic eon: 542 million years ago to
the present.
– Rapid speciation
– Divided into three geologic eras: the Paleozoic,
Mesozoic, and Cenozoic.
Geologic Time: Paleozoic Era
•
•
•
•
•
The first era of the Phanerozic eon.
542-521 Ma,
First vertebrates (early fish to tetrapods).
First reptiles = first land dwellers.
Therapsids: “mammal-like reptiles.”
Ancestors of early mammals.
Geologic Time: Mesozoic Era
• 251-65.5 Ma.
• Triassic, Jurassic, and
Cretaceous Periods
• “Age of Dinosaurs”
• First mammals (~200 Ma)
• Bird-like reptiles
• End of the Cretaceous
period = mass extinction
of the dinosaurs and many
other organisms.
Geologic Time: Cenozoic Era
•
•
•
•
•
•
65.5 Ma to present.
Primate and humans evolve.
“Age of mammals.”
Earliest primates = 50 Ma.
Earliest primitive apes = 20 Ma.
First hominins = 6 Ma
Fossils
• Paleospecies: Species
identified in the fossil
record. Identified
based on physical
similarities and
differences to other
species.
• Variation within
species: sexual
dimorphism, age, etc.
Paleoecology
• Paleoecology: the
study of past
environments.
• Palynology: the study
of fossil pollen. Plays a
large role within
paleoecology.
Past Behavior
• In order to evaluate the
behavioral patterns of
human ancestors,
paleoanthropologists use
comparative data from
nonhuman primates to
make analogies regarding
past populations.
– Early studies: baboons: due
to their savanna habitat.
Past Behavior
• Today, the chimpanzee is
most often used, because it
is the primate most related
to us.
• The bonobo has also been
used, it is equally related
to us, because these two
species split from each
other AFTER the hominin
line had already diverged
from them.
Key Terms
• Sites: Locations of discoveries; both in
paleontology and archaeology.
• Artifacts: Objects made or modified by
hominins.
Experimental Archaeology
• A subfield of archeology:
the study of manufacture
and use of tools in order to
learn how they were made
and used.
• The only tools once used
by human ancestors which
are still preserved are stone
(lithic) tools.
– How did they use these
tools?
Experimental archaeology can
help tell us!
Paleoanthropologists
Paleoanthropologists: Louis Leakey
• 1903-1972
• His idea to look for
evidence of human
ancestors in Africa was
revolutionary.
• Most famous
discoveries were in
northern Tanzania at
Olduvai Gorge.
Paleoanthropologists: Louis Leakey
• Proconsul Aficanus:
likely a common
ancestor for both
humans and other
primate species.
• Homo Habilis: “handy
man.”
Paleoanthropologists: Mary Leakey
• 1913 - 1996
• Married to Luis Leakey.
• Australopithecus Boisei:
(used to be known as
Zinjanthropus boisei)
• Laetoli Footprints
(belonging to
Australopithecus
afarensis).
Paleoanthropologists: Richard
Leakey
• 1944-present
• Homo erectus,
“Nariokotome Boy” (or
“Turkana Boy”)
• Director of the National
Museums of Kenya
• Head of Kenya Wildlife
Services (KWS)
• Conversationalist:
elephants and rhinos
Paleoanthropologists: Donald
Johanson
• 1943-present
• Worked mostly in
Ethiopia.
• With grad student
Tom Gray, discovered
the partial skeleton of
Australopithecus
afarensis, “Lucy”
(1974)
• Homo Habilis
Paleoanthropologists: Tim White
• 1950-present
• Teaches at Berkeley.
• Ardipithecus Ramidus
(Ardi)
• Worked with D.
Johanson on Lucy.
Additional Resources
• “Lucy’s Legacy,”
Donald Johanson
• “One Life,” Richard
Leakey
• “Origins,” Louis
Leakey
• http://www.time.com
/time/health/article/0
,8599,1882969,00.html