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We'll be right back.

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In reality, the herbivores can not reduce the food for certain reptiles and there are fewer plants and, logically, fewer herbivores.

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If a group of lizards has straighter legs and can run faster, they will hunt more herbivores, eat better, reproduce more frequently and their number will increase.

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On the contrary, slower reptiles will decrease in number when competing for food with the best adapted.

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Charles Darwin called this process natural selection back in the 19th century.

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But how do living beings manage to develop those characteristics that make them better?

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Let's say that in most cases it is a matter of luck.

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Its manual of construction and functioning instructions, that is, its DNA, changes, it suffers mutations.

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The DNA is the substance of the cells where the instructions are written in the form of phrases called genes that form books called chromosomes.

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Most of the mutations are bad and produce defective living beings.

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However, sometimes favorable mutations occur that make living beings better adapted to the environment,

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such as the increase in body size.

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When natural selection takes place, living beings evolve and new species are made

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better adapted to the environment, which can survive more easily.