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: Some [[variation]]s are [[heredity|hereditary]] which means they are passed on from parent to [[offspring]].
: If a [[heredity|heritable]] [[variation]] gives a member of the [[species]] an advantage over the others in its environment, then it is more likely to survive and reproduce. This is natural selection where some [[variation]]s cause [[organism]]s to die while other [[variation]]s cause [[organism]]s to have more [[offspring]].
{| class="wikitable"
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|[[File:GiraffeEvolution1.png|center|300px]]
|[[File:GiraffeEvolution2.png|center|300px]]
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| style="height:20px; width:200px; text-align:center;" |Millions of years ago all [[Giraffe]]s had short necks. [[Variation]] meant some [[Giraffe]]s were a little bit taller than others. Those [[Giraffe]]s could get to the higher leaves in trees. This meant they could eat more. The shorter [[Giraffe]]s couldn't get enough food and died. So the taller Giraffes survived and their [[offspring]] [[inherit]]ed their slightly longer necks.
| style="height:20px; width:200px; text-align:center;" |After a few generations all the [[giraffe]]s had slightly longer necks, but because of [[variation]] some had even longer necks still. This meant they they were more likely to get food, survive and have children than the shorter [[giraffe]]s. So their offspring [[inherit]]ed these even longer necks.
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|[[File:GiraffeEvolution3.png|center|300px]]
|[[File:GiraffeEvolution4.png|center|300px]]
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| style="height:20px; width:200px; text-align:center;" |This process of [[evolution]] repeated again and again.
| style="height:20px; width:200px; text-align:center;" |Millions of years later, after many generations, eventually all the [[Giraffe]] had very long necks.
|}
{| class="wikitable"