Lamarck's theory of evolution is based on the fact that

Lamarck's theory of evolution is based on the idea that organisms can acquire new traits during their lifetime through use or disuse of certain body parts, and that these acquired traits can be passed down to their offspring. In other words, Lamarck believed that an organism can change its characteristics over time, and those changes can be inherited by its offspring. This is known as the theory of inheritance of acquired characteristics. However, this theory has been largely discredited by modern science, as it is now understood that genetic information is only passed down through DNA, and not through changes that occur during an organism's lifetime.