2. Hominins
• Most paleoanthropologists believe a
common ancestor to the modern African
Apes (Chimps, Gorillas, Bonobos) and the
Hominins existed approximately 6-7 million
years ago.
• Hominins are habitually bipedal primates.
Modern humans are the only extant (living)
species of hominin.
3. Bipedalism
• The early ancestors of humans and the
ancestors of the African apes appear
very similar.
• The key point of difference between
early hominins and early apes were how
they walked: early hominins were
bipedal, early apes were quadrapedal.
4. Sivapithecus (12.5-8.5
million years ago).
possible ancestor of
modern Orangutans
(quadruped)
Paranthropus Boisei
(2.3-1.2 million years
ago) . Hominin (upright
walker)
5. Bipedalism: Advantages
• We are taller and more intimidating to
predators.
• Walking on two legs is more efficient in terms
of calories used.
• We are able to use our front limbs to carry,
use tools and to hunt and gather more
efficiently.
• We expose less of our bodies to direct
sunlight, allowing for more efficient cooling.
6. Bipedalism
• Given the similarities of early apes and
early hominins, the primary task is to
examine the skeleton to figure out how
this organism walked.
7. Anatomical marks of bipedalism
• Pelvis
• Femur
• Spine
• Foot
• Foramen Magnum
18. Difficulties in building a family
tree
• Creating a “family tree” for extinct species is
very difficult for two major reasons:
• A) The fossil record is incomplete (not all
organisms leave behind a record of their
existence and
• B) Many fossils are too old to derive DNA
from, making genetic comparisons
impossible.
19. Difficulties in building a family
tree
• Family trees of hominin and non-
hominin fossils are constantly being
redrawn as new discoveries are made.
• Additionally, different fossils may be
interpreted as the same species by one
anthropologist…and different species by
another.
20. Lucy
• 1974: Donald Johanson discovered
“Lucy”, a 3 foot 8 inch hominin later
classified as Australopithecus afarensis.
27. Big Brains and Bipedalism
• Bipedalism emerged long before big
brains.
• What started us on the journey to
becoming human was how we moved,
rather then the way we thought. Brain
changes came later.
28. Early Hominins
• The term Early Hominins is used to
describe the hominins that lived before
Genus Homo. They are all found only in
Africa.
• The fossil record indicates that there were
a variety of species of early hominins
adapted to various environments in sub-
Saharan Africa.
29. Robust vs. Gracile
• Hominins and other primates are
described as robust or gracile.
• A robust body is heavy in skeletal
structure and muscle. A gracile body is
more slender and fine-boned.
32. Speech
• Examinations of australopithecines
have determined their vocal tracts were
very similar to apes.
• As such it is unlikely that they used
spoken language.
33. Culture
• While it is safe to assume that the
majority of early hominins (like the
majority of primates) were social
creatures we know only so much about
their culture.
• It does seem to be the case that they
DID NOT make stone tools: that came
later in human evolution.
