Fallacious yet widespread and documented beliefs courtesy of Wikipedia.
Evolution does not plan to improve organism's fitness to survive. For example, an incorrect way to describe giraffe evolution is to say that giraffe necks grew longer over time because they needed to reach tall trees. Evolution doesn't see a need and respond to it. This mistaken view is known as Lamarckism. A mutation resulting in longer necks would be more likely to benefit an animal in an area with tall trees than an area with short trees, and thus enhance the chance of the animal surviving to pass on its longer-necked genes. Tall trees could not cause the mutation nor would they cause a higher percentage of animals to be born with longer necks.