The giraffe example is often used to explain not only
Lamarckian evolution, but also to show that Lamarck’s
explanation was wrong and that Darwin’s was correct. The
typical textbook teaches that the giraffe’s neck did not get
slightly longer after each generation because of stretching
to reach the upper leaves of trees, but because taller giraffes
had a selective advantage since they could reach the higher
tree leaves.12