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1. Prehistory: the Paleolithic Period
Australopithecus
Height:
1-1.40 m
Brain size:
400-500 cm
3
Dated:
4.2-1.5 million years
They had simian features, but
a more developed brain and
were bipeds. They lived in open
woodland. They ate fruit, seeds,
roots, root vegetables and some
meat.
1. THE PROCESS OF HOMINISATION
Gorillas, chimpanzees and human beings all belong to a group of mammals called
primates
. These species, including modern humans, descend from a common
ancestor.
Hominisation began with the appearance of a bipedal primate species in east Africa.
The members of this species walked on their back legs and are therefore considered
the first
hominids
.
The most significant anatomical changes that occurred during hominisation were:
❚
Bipedalism
, which occurred as a result of changes in the anatomy of the pelvis
and skull. The
upright position
enabled hominids to move around on their back
legs and use their front limbs to make and use tools
1
.
❚
The development of
opposable thumbs
, that is, the ability to press the thumb
against the other fingers of the hand. This enabled them to hold objects firmly,
making it easier to
do manual tasks
and make tools with greater precision.
❚
The gradual
increase in the size of the skull
and
brain
, and the development
of the forehead, which is associated with an
increase in intelligence
.
❚
The changes in the larynx, which made the development of
language
possible.
❚
The gradual reduction in the size of the
jaw
and teeth and the development of
the chin.
Genes are the part of a cell where an individual’s physical characteristics are
stored. This is the genetic information that children inherit from their parents. If
a change occurs in this genetic information (a mutation), this can be passed on
to the next generation. If this change becomes hereditary, this species changes
or a new species is created.
When two species (the one that has mutated and the original one) share the
same environment, the one that is least adapted will probably decrease in
number until it disappears. This explains why we are the only surviving hominids.
This theory is called evolution by natural selection and was developed by the
British naturalist Charles Darwin.
During the time of
Australopithecus
, the climate changed and the wooded
areas where they lived became savannahs with less vegetation. It became
increasingly difficult to obtain food. The genus
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Homo
adapted best to this
new situation.
1
tool
:
an implement used for a
particular function
2
genus
:
the category between species
and family, in the classification of living
things
A succession of changes in these ancestors occurred over time, resulting in the
emergence of different species of hominids.
The process of hominisation refers to the series of changes which gradually
occurred in these new species. From that shared ancestry, evolutionary
developments occurred over millions of years. This eventually led to the appearance
of the first human beings.
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