Since the change makes sense because the age of the earth makes sense. I think If the Earth didn't change, evolution would happen much more slowly, if it happened at all. Change in the environments is a driving force for evolution; if the environment were static, then the same biological designs that worked today, would work tomorrow, and the day after that, and the day after that. Adaptation would reach a peak and then evolutionary progress would slow to a crawl. An old earth is important to evolutionary theory because evolution takes time. Significant evolutionary change generally only happens over many generations; in the case of some organisms, a generation can last decades.