Of all the facts in The Origin of Species, embryology was the most important in support of the theory. In a letter to Asa Gray in September 1860, Darwin wrote – “embryology is to me by far the strongest single class of facts in favor” of the theory.

Then, just two months before the release of the first edition of The Origin of Species in September 1859, Darwin wrote to Charles Lyell, “Embryology in Chapter VIII is one of my strongest points I think.”

Darwin was fascinated by embryology. Writing in his autobiography, Darwin recalls: “Hardly any point gave me so much satisfaction when I was at work on the Origin, as the explanation of the wide difference in many classes between the embryo and the adult animal.”

To the point, Darwin writes – “We have seen in the first chapter that the homological [similar] structure of man, his embryological development and the rudiments which he still retains, all declare in the plainest manner that he is descended from some lower form.”

Darwin along with Fritz Müller (1821–1897) and Ernest Haeckel (1834–1919) were following in the footstep of Karl Ernst von Baer (1792–1876). Baer promoted the concept that a species’ embryological development (ontogeny) retraces the species’ entire evolutionary development (phylogeny).

In the case of man, then, the human embryo begins as a single cell and is progressively transformed into a tadpole, then to a fish, to an amphibian, to a monkey, and finally to man. In other words, at the different stages of development, the embryo is actually a series of ancestor species. The sequences of the embryo retrace the steps of evolution. Haeckel coined this process with the now-famous phrase “ontogeny recapitulates phylogeny.”

In the case of the appendix, then, the rise and fall of the appendix should be seen in the human embryo to demonstrate our presumed evolutionary human ancestry—from a functional to a non-functional organ. The question is does the evidence match the theory? The answer is – NO.

The reasons why the answer is NO, include  

• The appendix is not consistently found throughout the animal kingdom, occurring in only a few diverse mammals
• Not until the fifth fetal week does the appendix begin to develop
• Only after the fifth fetal month does the proximal end start differentiate into the true caecum
• Maximum growth of the appendix does not occur until after birth when the neonate takes on essential bacteria to reside in its colon
• Lymphoid follicles do not appear in the appendix until two weeks after birth at the same time that colonization of the large bowel with bacteria.

Contrary to the theory, at no point in the development of the appendix in the human embryo does arise and decline into a vestige organ. Rebecca E. Fisher, Ph.D., Postdoctoral Fellow from the Center for Functional Anatomy & Evolution Johns Hopkins University School of Medicine, in a review article entitled “The primate appendix: A reassessment” concludes that “the evolutionary history of the appendix has also proven difficult to trace.”  

The evidence on the development of the appendix now clearly stands to demonstrate the utter fallacy of the long-standing “ontogeny recapitulates phylogeny” theory of evolution.

Jerry Coyne’s (2009) contention in Why Evolution is True that, “our appendix is simply the remnant of an organ that was critically important to our leaf-eating ancestors, but is of no real value to use” is another clear example of deception used in the promotion evolution. The evidence is clear: the appendix is not an evolutionary leftover.