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Lecture

Jan 24 2012 notes.pdf


Department
Anthropology
Course Code
ANT203Y1
Professor
Xueda Song

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Paleoanthropology: Reconstructing Early Hominin Behavior and Ecology
Hominin
distinctive hominin characteristics include bipedal locomotion, large brain size, and
tool-making behavior
these characteristics have evolved at different rates throughout the evolutionary
history of hominins
hominin (as opposed to "hominid") is preferred as it reflects evolutionary
relationships
(image: compare traditional classification of hominoids, based on
morphology/adaptation, and the revised classification)
now hominids includes all great apes, and hominins specifies humans
Four main events in human evolution
arboreal to terrestrial
bipedalism
encephalization
culture/civilization
Two models for this evolution:
1. upright locomotion led to large brain (intelligence) and "humanity"
2. large brain (intelligence) led to bipedalism, which led to "humanity"
evidence suggests that the first model is more likely
Olduvai Gorge
source of a lot of evidence on the earliest hominin evolution
excavations 1930s-1980s by Mary and Louis Leakey
well-documented and correlated sequence of geological, paleontological,
archaeological, and hominin remains over the last 2 million years
paleontological evidence of over 150 species of extinct non-human animals with
clues to ecological conditions of early hominin habitats and fossilized hominins
Mioecene: very different environment in most of Africa than 2-3 million years ago
onwards
Paleoanthropological fieldwork and analysis includes evidence of...
dating
paleoecology
archaeological traces of behavior (esp. when toolmaking begins)
anatomical evidence of hominin remains
Required steps for interpreting the data - see textbook/slide
Looking to reconstruct lifeways - in terms of diet, environment, technology, and social
systems
Experimental archeology
used to understand how artifacts were made and used by reconstructing prehistoric
techniques
e.g. stone tool (lithic) technology, direct percussion, pressure flaking; analysis of

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microwear, analysis of phytoliths, analysis of bone (see: taphonomy)
Reconstruction of Environments and Behaviour
how early hominins evolved, why the process occurred by studying what is known
from the record
environmental explanations depend on environmental conditions at the time
environmental determinism directly links simple environmental changes to a
major evolutionary shift in an organism
this can be an oversimplification of the evolutionary process
Stable Carbon Isotopes are produced in plants in differing proportions and depending on
environmental conditions
they are analyzed in their proportions contained in fossil remains of hominins or
other animals (who ate the plants) to reconstruct aspects of ancient environments
Environmentally-based hypotheses
evolutionary pulse theory suggests arid climate during the Pliocene and Early
Pleistocene Africa stimulated hominin evolutionary development (example of
environmental determinism)
East African climate grew cooler 12-5mya; forest "fringe" habitats and
transitional zones became widespread; some hominoids exploited drier
grasslands in the fringes and others, wetlands
adaptations followed, including bipedalism, tool use, and dietary
specialization
see graphic illustration pulses of cold
Efficient (or Habitual) Bipedalism
efficient bipedalism as a primary form of locomotion is seen only in hominins
frees hands for carrying objects, making and using tools; hunting, gathering
seeds and nuts, and feeding from bushes
thermoregulation (better for sweating if upright; less surface area exposed to
direct sunlight)
better field of vision (i.e. further over the landscape
efficient means of covering long distance, provisioning by males of females
with dependents
Chapter 11: Hominin Origins in Africa
Mosaic evolution: a pattern of evolution in which the rates of evolution in one
functional system vary from those in other systems
ex. in hominin evolution, the dental, locomotor, and neurological (esp.
brain) systems all evolved at different rates
the bipedal adaptation
earliest hominins are all from Africa and date from after 6 Ma
most became extinct - why? were any of them our direct ancestors?
bipedal adaptation suggests most dramatic changes occurred in the pelvis
key: human ossa coxae
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