Over the past billions of years, many animals and plants have lived on this beautiful planet. But about 99.9 percent of them died out. This is because they couldn't adapt to (适应) where they lived. To survive, living things must change over time. This is called evolution (进化) .
When reading this article, please remember that every one of us is a lucky dog.We evolve, and we survive! After years of evolution, now we have the abilities to live in the world and enjoy it. Just like humans, other animals on Earth also evolve great abilities. For example, giraffes live on the grassland of Africa. To adapt to life there, they have evolved longer necks to reach the high trees, as well as longer legs to run away from lions and cheetahs (猎豹).
However, evolution also gives giraffes a strange habit: They only sleep for about 30 minutes a day and less than 5 minutes a time, and they sleep standing! Why are they so wakeful? Well, that's because they are so tall. They need longer time getting off the ground and run. Because of this special sleep style, they won't become easy meals for others.
As you see, evolution isn't always perfect. It helps animals to live, but it sometimes also gives them what they don't really want. Don't feel sorry. It's part of natural selection (选择). In order to survive, all of this is necessary.
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Facts About Evolution |
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Why evolution happens |
Humans and other animals on earth need to evolve great abilities to adapt to the . |
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Take giraffes for |
They have evolved longer necks to high trees, as well as longer legs to run away from dangerous animals. |
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They only sleep for a very short time and they sleep standing, or they will be eaten by others. |
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Whether evolution is perfect |
Evolution isn't always perfect. On the one hand, it helps animals to live. On the other hand, it sometimes can not just their needs. |
