Paleoanthropology. -The study of human origins and evolution. -Paleoanthropologists use two terms that are easily confused:. Hominoid : refers to the group that contains the great apes and humans. Hominid : refers to branches of the evolutionary tree closest to humans.
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-The study of human origins and evolution
-Paleoanthropologists use two terms that
are easily confused:
Hominoid: refers to the group that
contains the great apes and humans.
Hominid: refers to branches of the
evolutionary tree closest to humans.
2) Members of the genus Homo, with all
species extinct except one:
-This is close to the volume of a modern day
Modern humans have a brain volume of about
1,300 cm3 in size.
This tripling in size is associated with trends such
as the development of complex language and
had long prognathic jaws, similar to modern
day gorillas and chimpanzees.
During human evolution, the development of
shorter jawbones resulted in a flatter face with
a more pronounced chin.
Along with the change in jaw shape came a new
pattern of dentition (teeth), and a flattening in
the zygomatic arches around the eyes.
bones, and the flattening of the zygomatic
arches on the sides of the skull.
Also note that the modern human does not
have a sagittal crest.
clear that our ancestors walked on all four limbs
when they were on the ground.
The evolution of bipedal locomotion was linked
to key structural changes in the skeletons of
The pelvis of hominids evolved to be flatter and
Less narrow than those of the apes.
Our feet evolved to have all of the digits facing
forward, aiding in balance for walking.
In hominoids, the size difference between males
and females is a major feature.
Ex: In gorillas and orangutans, the size difference
is sometimes more than two times.
In humans, the average difference is 1.2 times.
and the Origin of Bipedal Posture
Australopithecus africanus: first discovered in
1924 by Raymond Dart.
“Southern Ape of Africa”
Discovered in a South African quarry, the fossil
Evidence was clear that A. africanus walked on
two feet, and had human-like hands and teeth.
Age: 2-3 million years
complete skeleton was found.
Nicknamed “Lucy”, she stood only about 1
The new species was named for the region in
which it was found.
The age given for A. afarensis is approximately
3.5 to 4.5 million years old.
confirmed evidence that A. afarensis walked in
a bipedal manner.
Skeletal evidence also indicated that A. afarensis
also led a partially arboreal existence.
Discovered in 1995 by Mary Leakey, A. amanensis
is one of the oldest known australopithecines.
Fossils found include parts of jawbones, arm
and leg bones. A complete skeleton has not yet
Dentition is marked more “ape-like”, with larger
canines and a parallel jaw structure.
A fossilized arm joint is more human like than
A relative of A. afarensis, this species had a very thick and heavy skull.
This species had a sagittal
Age: 2.1 – 1.6 mya
Disagreement exists over the placement of
both A. robustus and A. bosei in the hominid
It is widely held now that both
are relatives of A. africanus.
Age: 2.3 – 1.1 mya
2) Scientists believe that divergence between
Australopithecus and Homo occurred
between 3.0 and 2.5 million years ago.
and then to the more specialized A. robustus and
the variant A. bosei.
4) The other major branch led to Homo habilis,
the earliest member of the genus Homo.
5) Portions of the H. habilis population gave rise
to Homo erectus, and part of the H. erectus
population led to development of Homo sapiens.
7) Examination of the trends in evolution indicate
that not all organ systems have evolved at the
The concept that different features of an organism
evolve at different rates is known as mosaic evolution.
8) Efficient bipedal movement is a trait that
appeared very early, and it is probably the single
most important development in the emergence