The first ‘people’ to walk on two legs probably stood up about four to five million years ago in eastern Africa. But things started long before then: ten million years ago, the Earth’s climate was changing and the wet forests were disappearing. These were the natural home (or habitat) of apes. As the forests got smaller, so apes slowly evolved into animals that started to walk on two legs. But why did they need to do that? Scientists tell us that walking on two legs does not use as much energy and the sun shines on less of our bodies, so we don’t lose so much water. We can also carry things, see more because we are taller and reach for things higher up on trees. Another idea is that there were more lakes then than there are now and standing on two legs made fishing less dangerous.
The
Beginnings of Human Life
The first ‘people’ to walk on two legs
probably stood up about four to five million years ago in eastern Africa. But things
started long before then: ten million years ago, the Earth’s climate was
changing and the wet forests were disappearing. These were the natural home (or
habitat) of apes. As the forests got smaller, so apes slowly evolved into
animals that started to walk on two legs. But why did they need to do
that? Scientists tell us that walking on two legs does not use as
much energy and the sun shines on less of our bodies, so we don’t lose so much
water. We can also carry things, see more because we are taller and reach for
things higher up on trees. Another idea is that there were more lakes then than
there are now and standing on two legs made fishing less dangerous.
The first ‘people’ are now called
Australopithecus. This word comes from the Latin ‘australis’, which means
‘south’ and the Greek one ‘pithekos’ or ‘man’. They died out about
two million years later, maybe around two million years ago.
Of course, you might ask how we know
all this. Nowadays, we have about two thousand skeletons or
parts of skeletons from early versions of human beings;
only a hundred years ago, there were only five to ten bits of skeleton. This
doesn’t seem much, but scientists say that it’s the quality –
not the quantity – that is important.
For instance, if we find leg bones,
we know if the animal walked on four legs or two, because of the size of
the bones. Another important question is how we know where to look for
very early ‘people’. An obvious answer is to look where there
are apes.
After Australopithecus, scientists thought
that ‘homo habilis’ came along. They believed they were the first real
human beings because their skulls were much bigger than
Australopithecus. This meant they were probably more intelligent. But a few
years ago, we found a skeleton and it was very nearly the same as
Australopithecus. So, perhaps, habilis was not really homo (or man) at all.
This makes us think about the
all-important question: what makes a human being? Obviously, walking on two
legs is important and so is intelligence. If a skeleton has a large skull,
this probably means that it has a big brain and so is cleverer. There will also
be tools for killing animals and cleaning their skins and bones.
Bigger brains need a lot more food than smaller ones. A brain needs twenty-two
times the food that muscle needs. So, at the same time, we know that
people needed more and better food. Early human beings needed root vegetables
and meat to grow so fast, but they also had to learn other ways
of getting these.
Big cats found it easier to get meat
because they could run faster but man learnt how to frighten the big
and dangerous animals away from the meat they had killed and to eat it for
himself. They also learnt that they had to share food to survive –
especially if they wanted children.
This is a major difference
between apes and
human beings. After a short time, young monkeys must look after themselves, but
human children continue to get the food that their parents find. Because of
this longer time with their stronger mothers and fathers, not so many die. This
is not a biological change or a climatic one – but a change in social
organisation or how people live together and look after each other.
So, around two million years ago, there
were different kinds of early ‘people’ living at the same time. Did they have
sex and make children together? We think they probably did not or, if they did,
they were unlikely to produce children. Chimpanzees, for instance, do not
make families with gorillas; lions are not the same as leopards. They may look
the same or similar to us, but they might look very different to each other!
Another thing is that we don’t know if
they show interest in the same ways. A chimpanzee makes certain signs to show
that she wants to have sex, but does a different type of monkey understand
these? Now, we know that homo sapiens has some Neanderthal blood and so sex
between species did happen and children were the result – but not
enough for all the different types of early hominid to mix into one.
We think then that there were many
different types of early hominids – perhaps about fifteen – but they
did not make families or groups together. Most died out. They were experiments that
lived for hundreds of thousands of years but then did not change enough
to survive.
The first ‘homo sapiens’ probably developed about
100 – 150,000 years ago. They certainly came from hominids walking on
two legs, but only from one group of them. It was this new group that moved out
of Africa because the continent started to become dry and there was less food.
So, the reasons we change have a lot to do with climate. We have not developed in one line, with one successful species going to another. There were a lot of mistakes too. We have been on the planet for about a hundred thousand years – not very long – and the thing that will probably kill us is that our children nearly all live to make more children of their own. There are simply more and more of us every year. It can’t continue forever.
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