Explain how the scientific theory of evolution is supported by observed evolutionary change

The theory of evolution is the statement that species change over a long period of time. Species such as the blue butterfly have adapted to their surroundings, and have slowly evolved into that of a red butterfly. The blue butterflies were eaten by birds that could only see blue, so the butterflies changed their physical appearance so as not to get eaten by the birds. Charles Darwin supported his theory of evolution by sailing around the world aboard the HMS Beagle. He found that some birds had thick, short beaks to crack open large seeds better, but some still had long, thin beaks that were of no use to them. He discovered that giraffes with longer necks had an advantage that giraffes with shorter necks did not. Charles Darwin supported his theory with lots of evidence while he sailed on the Beagle. 
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