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Monday, October 19

  1. page Evolution and natural selection edited Evolution People often say we are like our parents. We often look like them, sound like them or…

    Evolution
    People often say we are like our parents. We often look like them, sound like them or do the same kinds of things.
    We are not exactly the same as our parents, though. There are always little changes.
    The same things happens to animals. Baby animals are quite like their parents but not exactly the same.
    The way humans and animals change like this is called evolution.
    Over millions of years, all the little changes can add up into big changes. After a long enough time, the changes can be so big that one type of animal can evolve into a whole new type of animal.
    Natural selection
    Everybody is good at something, and we all have things we find difficult, too. Luckily, most of these things don't really matter - it's nice if you can run fast, but it won't kill you if you can't.
    If you were a cheetah, running fast would be important because you would need to catch antelopes. A cheetah that could not run fast enough would not be able to catch any food and would die. Occasionally a cheetah will be born which can't run fast enough, and it probably will die. It is sad to think about it but that is how nature works.
    Because only fast cheetahs can survive, and because baby cheetahs will be quite like their parents, most baby cheetahs grow up to run quickly. It can seem like nature has "chosen" (or selected) the fastest cheetahs (but of course nobody did the choosing - it is just that only the fastest survived). This choosing by nature is sometimes called survival of the fittest but its proper name is natural selection.
    Adaptation
    When evolution and natural selection work together, it can seem like animals or plants have changed themselves (or been designed) to do a particular job well. This is called adaptation - we say the animals or plants have adapted to survive in their environments.
    It is not only speed which help animals survive. Tortoises are slow but over millions of years, they have adapted by evolving hard shells to protect them. Some animals evolved feathers on their arms and small bodies until they were light enough to fly - we call them birds. Giraffes have long necks so they can reach the highest leaves on trees when other animals have eaten all the lower leaves. Some animals (including humans) have adapted to do more complicated things by evolving opposable thumbs which enables them to grip things. (Imagine trying to hold something with your toes - it's much harder than using your hand!)
    It works for plants, too: Trees are tall so that they can grow above all the others plants to reach the sunlight they need to survive. In fact, some trees have adapted by growing thin trunks very quickly so that they "get there first" (but might be snapped by strong winds) whereas other trees have evolved to grow very thick, strong trunks (but they take longer to grow so they might never see enough sunlight). Nettles have evolved stings to stop animals eating them or treading on them. Other plants have evolved ingenious ways of spreading their seeds far and wide so that more of them will grow.
    What about humans?
    We don't know every detail of our history but scientists and historians think they have worked out most of it.
    We think life started in the sea. Some chemicals mixed together and made something that could copy itself. You might think this sounds pretty unlikely - and you'd be right - but it only needed to happen once, and we think it was about 4,000,000,000 (4 billion) years ago.
    Over millions of years, that life became more complicated. Bacteria evolved into fish, some fish evolved fins and some of those fins became longer and stronger. Most fish can only breathe under water but some evolved the ability to breathe air. Some of the animals that could breathe air started moving around on land, out of the water and their fins evolved into legs. Some of these animals grew stronger back legs and lighter front legs until they were able to stand upright. Some animals evolved fingers and toes so they could climb trees. Some animals grew larger brains so that they could solve problems in order to survive - that's us!

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  2. page home edited ... mountains Australia Evolution and natural selection
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    mountains
    Australia
    Evolution and natural selection
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Saturday, October 25

  1. page Australia edited ... Geography It is the sixth largest country in the world, about the same size as the USA or Bra…
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    Geography
    It is the sixth largest country in the world, about the same size as the USA or Brazil. It is surrounded by water (the Indian Ocean to the West and the Pacific Ocean to the east) and a few smaller countries, like New Zealand and Indonesia. On a globe, it is almost opposite England (but not quite).
    {http://tatfoundation.org/australia.gif} external image australia.gif
    Australia is divided into seven territories, which are a bit like "counties" in England (but much bigger):
    Western Australia
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    7:27 am
  2. page Aborigines edited ... Aboriginal artists discovered they could make paint using the things around them, such as by r…
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    Aboriginal artists discovered they could make paint using the things around them, such as by rubbing rocks together to make coloured dust and mixing them with the end of a dead stick.
    The Dreamtime
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    is called Dreamtime .Dreamtime. There are
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    7:26 am
  3. page Aborigines edited {man man.jpg} The first people of Australia were the Aborigines. (The word "Aboriginal&qu…

    {man man.jpg}
    The first people of Australia were the Aborigines. (The word "Aboriginal" means "the first" or "earliest known".) It is believed that they came to Australia around 50,000 years ago and were the first group of humans to travel from Africa. They would have travelled through India, Malaysia, Borneo and Papua New Guinea. The final journey to Australia was over sea and would have been made by raft or canoe.
    There are approximately 500 Aborigines living in Australia today. They live in small clans or tribes, each having their own language and territory. Aborigines don't usually have beards but often have lots of hair on their heads.
    Aboriginal problems
    When the British first went to Australia, they wanted the land for themselves. Even though there were Aborigines living there, the British made a law saying that the land of Australia belonged to nobody so they were allowed to claim it as their own. Many Aborigines suffered because their land was stolen in this way.
    Aboriginal art
    {http://www.aboriginalartshop.com/wp-content/uploads/aboriginal%20painting%20-%20colour.jpg}
    {frill_necked_lizarda.jpg}
    Aboriginal art has survived for thousands of years and remains as one of the oldest types of art. Aboriginal artists usually based their wonderful art work on patterns, animals and landscapes.
    Aboriginal artists discovered they could make paint using the things around them, such as by rubbing rocks together to make coloured dust and mixing them with the end of a dead stick.
    The Dreamtime
    Aborigines believe that they have animal, plant, and human ancestors who created the world and everything in it. This process of creation is called Dreamtime . There are many songs and stories about Dreamtime, which aboriginal people have passed down to their children for many years.

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    7:26 am
  4. page Australia edited ... Most of Australia is very hot and dry but the climate is cooler in the south and east, so most…
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    Most of Australia is very hot and dry but the climate is cooler in the south and east, so most people live here. Because Australia is so dry, most cities are near the outside, near the sea, and not many people live in central areas (called the Outback).
    When people from Europe first discovered Australia, they found people already living there. Those people are called Aborigines.
    Territories of Australia

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    7:11 am
  5. page Territories of Australia (deleted) edited
    7:11 am
  6. page Australia edited ... Most of Australia is very hot and dry but the climate is cooler in the south and east, so most…
    ...
    Most of Australia is very hot and dry but the climate is cooler in the south and east, so most people live here. Because Australia is so dry, most cities are near the outside, near the sea, and not many people live in central areas (called the Outback).
    When people from Europe first discovered Australia, they found people already living there. Those people are called Aborigines.
    Sport in Australia
    Australian wildlife
    Housing in Australia

    Territories of Australia
    Australia's weather and climate
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    7:10 am
  7. page Australia edited Australia {https://upload.wikimedia.org/wikipedia/commons/thumb/b/b9/Flag_of_Australia.svg/500…

    Australia
    {https://upload.wikimedia.org/wikipedia/commons/thumb/b/b9/Flag_of_Australia.svg/500px-Flag_of_Australia.svg.png} Australia is a
    ...
    the world). ItIts capital city is called Canberra and its flag is a small Union Flag with white stars on a dark blue background.
    Geography
    It is the sixth largest country in the world,
    about the
    ...
    USA or Brazil andBrazil. It is surrounded by oceanwater (the Indian Ocean to the West and the Pacific Ocean to the east) and a
    ...
    not quite).
    Aborigines

    {http://tatfoundation.org/australia.gif} external image australia.gif
    Australia is divided into seven territories, which are a bit like "counties" in England (but much bigger):
    Western Australia
    South Australia
    Northern Territory
    Queensland
    New South Wales
    Victoria
    Tasmania
    People
    Most of Australia is very hot and dry but the climate is cooler in the south and east, so most people live here. Because Australia is so dry, most cities are near the outside, near the sea, and not many people live in central areas (called the Outback).
    When people from Europe first discovered Australia, they found people already living there. Those people are called Aborigines.

    Sport in Australia
    Australian wildlife
    Housing in Australia
    Territories of Australia
    WeatherAustralia's weather and climate
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    7:04 am

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