The study of the formation and development of the embryo is very useful in evolutionary biology in order to determine similarities derived from a common ancestor (i.e. homologies). In consequence, embryology is a discipline used to establish relationships between species and higher taxa. For example, vestigial organs and/or tissues (e.g., tails in humans) can be observed in the embryos during the first stages of development. In this regard, embryology has been an important aspect of the evolutionary theory proposed by Darwin (1859) by evidencing the process of species radiation from their ancient ancestors.
