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Hominins
This is the Hominid sub group made up of human and their human like ancestors
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Several other hominin forms are now
extinct such as Homo Habilis and Australopithecus
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This means they they
are not only capable of walking on two legs, but that it is their habit to do so
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The features of Hominins ultimately relate to their bipedal lifestyle
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Describe trends of biological evolution with respect to skeletal changes linked to
bipedalism
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Humans have taken this to the extreme and walk on two
legs all of the time
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It is
thought that being bipedal allowed humans to exploit the ground niches, which probably
offered more variety of food at a time when forests were shrinking
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This change to bipedalism was
probably the most important step in our evolution because it freed the hands, allowing us to
take advantage of our larger brain
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● The human pelvis is relatively short and strong in a bowl shape in order to carry the
weight of an upright body whereas Apes have a longer narrower pelvis
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This brings the knees and feet nearer the midline, which enables more efficient two
legged walking compared to chimpanzees
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In apes the knees bend outwards under the hips as their
femur angled into the knee so when they lift one foot off the ground they lose
balance
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This produces a swaying
movement as they walk
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This is so that the eyes can face forwards when standing
upright
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Their feet are
also flat
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● Human​ hands​ are much smaller than a chimpanzee’s, the thumb is relatively long
and more mobile
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A
chimpanzee's hand is not suited to a precision grip but human hands can have both a
power grip and a precision grip
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Like all primates both can grip
objects with a ​power grip​, but only humans can also use a ​precision grip​
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Apes had a ​flatter brain case​ (smaller b

Summary of adaptations for bipedalism

Position of the foramen magnum

Moved from the back to the centre of the skull – this
allows the skull to balance on top of the spine and
less energy expenditure is required by the muscles in
the neck to keep the skull upright
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This improves
balance
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This allows the
weight of the chest to sit above the pelvis, rather
than further forward
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Pelvis shape

The pelvis has become more bowl shaped (broad and
short)
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The bowl shaped pelvis also increases the surface
area for the attachment of large buttock muscles
(gluteus maximus)
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This assists the upper body to be
positioned above the centre of gravity for walking
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Knee joint

The bottom of the femur (the knee joint) has a
buttress of bone called the lateral condyle, that stops
the sideways deflection of thigh muscles during
walking
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The toes are short, with the big toe beside the
others and forward thrusting (ie it is
non-opposable)
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(b)​ ​The weight is placed on the outer edge with
the inner side elevated into an arch
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Femur (thigh bone)​: Bipedal standing increases the weight on each leg, and the area of the
joint surfaces​ of the femur (upper leg bone) reflects this
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Hands​: As apes developed the habit of brachiating, the thumb became reduced, using the
fingers more as hooks
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More significantly the
first metacarpal (hand bone at base of thumb) is connected to the wrist by a ‘saddle’ joint,
which enables the thumb to be brought across the hand so that it can touch the tip of the
first or any other finger
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Humans also have an independent muscle / tendon dedicated to
flexing the last joint of the thumb (apes cannot flex their thumb independently)
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Changes in skull and endocranial
Apes

H
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Foramen magnum
on angle/back of
skull

Foramen magnum
central/bottom of skull

Vertical spine with skull on top

No Broca’s and
Wernicke’s areas

Broca’s and Wernicke’s
areas present

Used for language

Less folding of
cerebral cortex

Cortex much more
folded

Related to memory, attention,
language, awareness, thought, etc…
developed as social structure allows

more time, and hands free to carry
out abstract tasks
Cerebellum less
developed

Cerebellum more
developed

Needed for balance, as well as
coordination and tool use

Trends in human cultural evolution between hominins
with respect to tool manufacture and use
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g
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Mousterian ​first used by Neanderthals
● Sophisticated tools which were finely worked, made of stone
but often
had other materials attached for more accurate handling
● These tools require high levels of skills and time to learn and
make e
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spear, axes, scrapers etc
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● Tools included things like needles, ropes, nets, snares
etc
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Farming and domestication:
● Early humans were nomadic hunter-gatherers, relying on what was present in the
environment and moving as the population grew or resources ran out
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Then millet, rice, soya beans,
yams, maize,
● beans, cotton etc
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They were able to produce more
food than they needed so traded with other people for other things they needed
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● Made technological advances (e
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wheel, plough, hoe) which eventually led to the
Industrial revolution
Disadvantages of farming
● Their diet was restricted to what they could grow
● They become more dependent on the weather for their crop growth
● Because there was a higher population disease carrying and disease causing
organisms flourished as
● they had more people closer together to infect e
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rats, fleas, viruses etc
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is quite time consuming
● People begin to fight over ownership of animals and territory

The discovery of fire and development of tools also helped in terms of acquiring food
aswell as preserving and eating food for later

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