How the concept of ladder of progress took hold

This ladder tells us that evolution has produced changes favorable to the species (like climbing a ladder) and has done it progressively in small proportions. With each change needed for adaptation, the species has become better and better. Various methods have provided the evidence for this ladder of progress. The unearthing of fossils and their study, biogeography which informs us of similar species of trees and animals in various parts of the world and the reasons for such an eventuality, embryology and the study of the remaining vestigial structures in animals and human beings are some of the methods used to collect evidence of the evolutionary progress.