Hominids first appeared between 6-7 million years ago in Africa. They have evolved several times, as evidenced by fossil records. Key adaptations in hominid evolution included bipedal locomotion, larger brains and cranial capacities, changes in skull shape and jaw size, and opposable thumbs. Major hominid species included Homo habilis, Homo erectus, Homo sapiens, and Homo neanderthalensis. Homo sapiens are the only surviving hominid lineage.

1. Hominid Evolution

2. Hominid Evolution
• Hominids family of organism
that includes humans
• First appeared between 6 and 7
million ears ago
• Has evolved several times..we can
tell by looking at fossil
evidence…Skulls in particular

3. Hominid Evolution
• Today researchers believe Hominid
evolution proceed by
• Adaptive radiation is a process by
which a several species evolve from
single ancestral species.

4. Hominid Evolution
• Adaptations in hominid
evolution include …
• Bipedal locomotion-walking
upright on 2 legs
• Large brains- specially
cerebrum; Increase in cranial
capacity
• Changes in skull shape,
including decrease in size of
brow ridge (section of bone
above eye)
• Decrease in jaw size and
angle at which jaw
protrudes from face
• Decrease in the number of
teeth
• Opposable thumbs- adapted
for grasping

6. • Homo habilis-
– Oldest…existed 2 million years ago
– handy man.” fossils found with tools
• Homo erectus means upright human
– Existed 1.6 million years ago to about 200,000 years ago
– Taller and larger brain than Homo habilis
– Smaller teeth than Homo habilis
– Lived in groups (suggest language use) and used fire
• Homo sapiens- means wise human
– Existed about 100,000 to 200,000 years ago
– Some believe they arose directly from Homo erectus while
other believe they arose from Homo Neanderthals (who
descended from Homo erectus)
– By about 40,000 years ago, H. sapiens were physically
identical to modern humans
• Homo neanderthalensis - Neanderthals
– Emerged in Germany 300,000 years ago
– Lived till about 30,000 years ago
– made stone tools and lived in organized social
groups and had organized societies
– Brain was similar in size to modern humans
– DNA evidence now supports this theory…modern
human DNA is 99.7 % identical to that of the
Neanderthals

8. Embryology Zygote formation
Cleavage
4 cells
• Zygote
– When male gamete fertilizes female gamete Morula
– Gametes fuse, making one new cell with
chromosomes from both parents Blastocyst
– Zygote will divide into 2 new cells…each of
those into 4 and so on…
– Cleavage  division of embryonic cells to
form two new cells
• Genetic material is copied before each cleavage
• Blastula
– Hollow ball of cells
• Gastrula
– When blastula implants itself on the uterine
wall (to get nourishment from mother)
– Ball of cells composed of three layers “GERM
LAYERS” (undifferentiated)

10. Gastrula
• Germ layers
– Differentiation
the process by
which a cell
develops in
different ways to
perform different
functions…begins
with the forming of
three germ layers
– Ectoderm
• Outer layer
• Forms skin, nerves
and sense organs
– Mesoderm
• Middle layer
• Forms bones, muscles
and connective tissue
– Endoderm

11. Fetus
• When the structures of the
developing embryo have
become distinguished
• Cells have differentiated into
their permanent role in that
organism