Yesterday afternoon I finally finished reading F.J. Cole's History of Comparative Anatomy from Aristotle to the Eighteenth Century. As discussed in this post, an underlying theme of the book is that the main purpose of comparative anatomy is to help find which organs may be homologous between different species.
The early anatomists did occasionally notice homologous organs between otherwise very different species. For example, Belon in the mid-16th century compared the human and bird skeletons and noted what he thought were the homologous bones in the 2 types. However, neither he nor any of his successors could make heads or tails of their findings. They could not, for example, explain the puzzling anatomical relatedness of certain "fishes", such as dolphins and whales, to terrestrial mammals. Cole writes:
We thus see that Belon demonstrated the importance of comparative studies as early as 1555, but the significance of the homologies then disclosed was not recognized by himself, or by Goethe, pondering similar facts, over two hundred years later. The lapse of time therefore had left the situation almost unchanged...Descriptive anatomy had served its purpose, and could do no more.However, the early anatomists were not totally lost and they did have an underlying rationale of sorts. Cole explains:
...community of structure might be established between two organs without the inference being drawn that they were historically related. Such community was often regarded as evidence of design in the sublime scheme of the Creation, in which case organisms were as independent of each other as are the variations on a theme in a musical composition...But why would an intelligent designer have put mammals in the sea? Such questions were, however, not allowed. Therefore, creationism was, and still is, a cul de sac. Creationism, by its very nature, did not allow for speculation outside its narrow limits and could not lead to understanding. Once the dead end was reached, all progress necessarily came to a halt. Cole continues:
Progress depends on the influence of some energizing and integrative speculation, sound or unsound, which is sufficiently bold and provocative to attract supporters and opponents, eager to investigate its validity. Without such a stimulus the observer is for ever groping in the dark for the switch he cannot reach.Eventually, a new road was found and the cul de sac was completely avoided and left behind.
We know now that the theoretical basis of comparative anatomy is the genetical history of animals, or in other words the principle of evolution.Cole’s book dates from 1949. Creationists are still and will always be groping in the dark.