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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 brain) which allows for greater muscle attachment
sites needed for aggressive facial displays
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It is very likely that large
teeth and large jaws are associated with diets high in fibrous plant food
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These stresses are resisted by the ​brow ridges above the eye sockets and
the ‘siminian shelf’​ that strengthens the inside of the lower jaw
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● Canine teeth ​in males and females are the same size in humans but in apes they are
much larger in males
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​ Not the case in humans
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● Hair loss helped as our ancestors lived in tropical Africa and lived and worked
outside, so it helped to evaporate sweat and keep cool by having thin hair
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● Apes had a shorter ​Pharynx tract​ this was one of the reasons they cannot have
spoken language
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● Increase in brain size is mainly due to the increase in
size of the ​cerebrum​
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● Wernicke’s area ​is a sensory region concerning the
interpretation of sound
● Broca’s area ​is a motor region, responsible for the interpretation of sound into
meaningful sequences
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● Cranial capacity changed from about 400cc to 1500cc
Apes have a much smaller brain size 450cm​3 ​vs 1400cm​3
Chimpanzee’s have a brain size of 400cm​3

Apes (quadrupedal)

H
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Pelvis is long and narrow

Pelvis short and
wide

Supports organs above​, also must allow
for bigger head during birth
Changed ​shape of the hominin pelvis
beneficial in locomotion:
Changes ​position of muscle attachmen​t
more efficient locomotion;
Carrying angle​ – more efficient
locomotion because movement
notside to side (or implied) /
balance /stability when walking

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