Homework
Guided Reading – Recent Hominids (#22-31)
Need ear buds/headphones for Monday!!
Learning Target
I can explore various hominids from the
skull lab and describe the evolution of
hominids.
What are the changes that led to
hominids and bipedalism in East
Africa?
Place events in order under their correct
change: Geologic; Climate; Habitat & Species
1.
Savanna grasslands form in East Africa
2.
Central Africa is all tropical (apes are diverse)
3.
East Africa became cooler & drier due to mountain range and change in
ocean currents
4.
West Africa remained a tropical rainforest
5.
Bipedal primates evolve in East Africa
6.
Great Rift Valley forms isolating East Africa & connection of North &
South America
Geologic Change
8MYA all of central Africa was tropical
 6MYA Great Rift Valley forms isolating East Africa
 North & South America are joined by Central
America

Climate Change

East African climate became cooler & drier due to
mountain range and change in Atlantic ocean
currents
Habitat Change
In East Africa tropical rainforests became savanna
 West Africa still existed as a tropical rain forest

Species Change

Primates of East Africa adapted becoming bipedal
The Great Rift Valley
Remember: There have been hundreds
of fossilized hominin specimens found
since the mid 1800s.
The earliest hominins
(Australopithecines) are only
found in Africa, while
members of our own genus
(Homo) migrated into Europe
and Asia.
Hominid Jigsaw
Each person will have 1-2 hominids to read and take
notes on
 Once everyone at the table is finished, share your
notes for a completed worksheet
 Bring your completed worksheet to me for the next
page – use your notes to answer each question
 Use notes on evolution in ISN to complete the maps
on the back page. Use article to help you.

Australopithecus afarensis
The species A. afarensis is one of the better
known australopithecines, merely with
regard to the number of samples attributed
to the species. Possibly the best-known
specimen of afarensis is "Lucy“, a 3.2 million
year old partial skeleton found in 1974 at
Hadar, Ethiopia in East Africa. Afarensis
fossils are found from 3.9-3.0 million years
ago. This species is also extremely
important in that there is good evidence
that the species was bipedal in a human-like
manner. Their pelvis and leg bones far
more closely resemble those of modern
humans. Afarensis had an apelike face with
a low forehead, bony ridge over the eyes, a
flat nose and no chin. They had protruding
jaws with large back teeth. Cranial capacity
varied from 375 to 550 cubic cm. The skull
is similar to that of a chimpanzee, except for
the more humanlike teeth. Females were
substantially smaller (3’6”) than males (5’).
They likely had a vegetarian diet of fruits,
seeds and soft roots.
Australopithecus boisei
Specimens attributed to A. boisei have been
found mostly in Ethiopia, Tanzania, and
Kenya in East Africa. Boisei had large and
extremely powerful jaws with a sagittal
crest along the top of their skulls. These
adaptations allowed them to feed on hard
low-quality foods like hard roots and nuts.
Because of this it has been given the
nickname “nutcracker man”.
A. boisei existed between 2.1 and 1.1 million
years ago. It was similar to robustus, but the
face and cheek teeth were even more
massive, some molars being up to 2 cm
across. The brain size is very similar to
robustus, about 530 cubic cm. A few experts
consider boisei and robustus to be variants of
the same species.
Australopithecus robustus and boisei are
known as robust australopithecines,
because their skulls in particular are more
heavily built. They have never been serious
candidates for being direct human
ancestors. This lineage may have died out
due to overspecialization to a specific
environment, and when the environment
changed, evolution could not keep up.
Homo habilis
H. habilis is nicknamed the "handy man“. This is
because it was the first hominid with fossil
evidence of tools found with its remains. Its diet
included some meat but mostly vegetation.
Habilis existed between 2.4 and 1.5 million years
ago. It has some similarities to australopithecines.
The face is still primitive, but it projects less than
early Australopithecines. The back teeth are
smaller, but still considerably larger than in
modern humans. The average brain size, at 650
cubic cm, is considerably larger than in
australopithecines. Brain size varies between 500
and 800 cubic cm. The brain shape is also more
humanlike. It may have had the capability of
basic speech. Habilis is thought to have been
about 5’ and about 100 lbs in weight, although
females may have been smaller.
Habilis has been a controversial species.
Originally, some scientists did not accept it as its
own species, believing that all habilis specimens
should be assigned to either the
australopithecines or Homo erectus. Habilis is now
fully accepted as a species, but it is widely
thought that the 'habilis' specimens have too wide
a range of variation for a single species, and that
some of the specimens should be placed in one or
more other species.
Homo erectus
H. erectus existed between 1.8 million and
300,000 years ago. Like habilis, the face has
protruding jaws with large molars, no chin,
thick brow ridges, and a long low skull, with a
brain size varying between 750 and 1225 cubic
cm. Early erectus specimens average about 900
cubic cm, while late ones have an average of
about 1100 cubic cm. The skeleton is a little
more robust than those of modern humans, but
still very similar. Their diet was varied but did
include some meat. Studies of skeletal fossils
indicates that erectus may have been more
efficient at walking than modern humans,
whose skeletons have had to adapt to allow for
the birth of larger-brained infants. Erectus is the
first hominid with evidence of migrating out of
Africa. Homo habilis and all the
australopithecines are found only in Africa, but
erectus was wide-ranging, and has been found
in Africa, Asia, and Europe. There is evidence
that Erectus probably used fire and their stone
tools are more sophisticated than those of
habilis.
Homo neanderthalensis
Neanderthals existed between 230,000 and 30,000
years ago. The average brain size is slightly larger
than that of modern humans, about 1450 cubic cm,
but this is probably correlated with their greater
bulk. Like erectus, they had a protruding jaw and
receding forehead. The chin was usually weak. The
midfacial area also protrudes, a feature that is not
found in erectus or sapiens and may be an
adaptation to cold. Neanderthals mostly lived in
cold climates, and their body proportions are
similar to those of modern cold-adapted peoples:
short and solid, with short limbs. Men averaged
about 5'6" in height. Their bones are thick and
heavy, and show signs of powerful muscle
attachments. Neanderthals would have been
extraordinarily strong by modern standards, and
their skeletons show that they endured brutally
hard lives. A large number of tools and weapons
have been found, more advanced than those of
Homo erectus. Neanderthals were very good
hunters, that relied heavily on meat in their
generalized diet. They were the first people
known to have buried their dead, with the oldest
known burial site being about 100,000 years old.
They are found throughout Europe and the
Middle East.
Homo sapiens
Modern forms of Homo sapiens first appear about
120,000 years ago in East Africa. They have a
generalized omnivore diet. Modern humans
have an average brain size of about 1350 cubic
cm. The forehead rises sharply and eyebrow
ridges are very small. About 40,000 years ago,
tool kits started becoming more sophisticated,
using a wider variety of raw materials such as
bone and antler, and containing new implements
for making clothing, engraving and sculpting.
Fine artwork, in the form of decorated tools,
beads, ivory carvings of humans and animals,
clay figurines, musical instruments, and
spectacular cave paintings appeared over the
next 20,000 years. They migrated across the
globe and into the Americas by about 12,000
years ago
Even within the last 100,000 years, the long-term
trends towards smaller molars and decreased
robustness can be measured. The face, jaw and
teeth of 30,000 year old humans are about 2030% more robust than ours. Interestingly, some
modern humans (aboriginal Australians) have
tooth sizes more typical of early sapiens. The
smallest tooth sizes are found in those areas
where food-processing techniques have been
used for the longest time.