Evolutionists often cite comparative embryology as evidence for universal common descent. This idea originated from recapitulation theory, which assumed fetal development mirrors evolutionary history, but is this really plausible or simply imaginative speculation?
The concept known as recapitulation theory, which posits that fetal development mirrors evolutionary development, was formulated by Étienne Serres in the 1820s, predating Charles Darwin's *Origin of Species* by several decades. This theory was grounded in the earlier work of Johann Friedrich Meckel. Ernest Haeckel, known as Darwin's bulldog, is infamous for promoting evolutionary theory with a fraudulent embryo chart that remained in textbooks long after being debunked.
Today the field of evolutionary biology of using comparative development processes of different species to figure out ancestral relationships is called Evolutionary Developmental Biology. It is based on the fact that only a relatively small fraction of an organism’s genome controls the developmental process. Hox genes are among are one such gene that is nearly universal among organisms commonly studied in this manner. Comparing these genes is often used as evidence for common ancestry.
The problem with this idea is that it ignores the fact that independently created organisms would still have similar hox genes if they were similar biologically, because of their use in the developmental process. What their similarity actually does is show a common source. If these organisms developed by naturalistic evolutionary process then these similarities would be evidence for common dissent.
If they were designed by an intelligent designer the same similarities would be evidence for a common designer. Consequently, calling such similarities evidence of universal common descent evolution actually presupposes common descent, and is just investigating the details. This makes the claim that this is evidence of universal common descent evolution a form of circular reasoning. This is because they are actually starting with the presupposition of universal common descent and excluding the possibility of a common designer, before looking at any evidence.
The following are examples of the specific similarities claimed as evidence for universal common descent. While they are commonly claimed as evidence for universal common descent, it turns out that each of them serves a useful developmental purpose, is being mislabeled in favor of universal common descent, or results from developmental problems.
Some examples include:
- Lanugo is very thin, soft, often colorless hair that sometimes covers a fetus or newborn. It is the first hair produced by fetal hair follicles, appearing around the sixteenth week and covering the body by the twentieth week. Usually shed before birth at seven to eight months, it may occasionally be present at birth but typically disappears within a few weeks. Despite being claimed as evidence for universal common descent, it provides insulation to the unborn child, indicating that it serves a useful purpose, suggesting the possibility of design.
- The so-called yolk sac in the early development of human beings is a classic example of labeling something under the presupposition of universal common descent and then using it as evidence for the same. This form of circular reasoning is frequent when evolutionists are presenting so-called evidence for universal common descent. In the case of humans and other mammals, the so-called yolk sac serves the purpose of producing blood early in the development process. Unlike the actual yoke sac in egg-laying animals, this structure does not supply food but simply serves the process of producing blood cells. It has been superficially referred to as a yoke sack by evolutionists and a wishful thinking and desperation to find evidence for their theory.
- Another claim frequently used by evolutionists as evidence for universal common descent is the fact that terrestrial frogs and salamanders hatch out of their eggs fully ready for land life, but while in the larval stage, they had many of the same features as aquatic larvae. First of all, the most this implies is that the terrestrial species had common ancestors with similar semi-aquatic species. This means that it could be a simple environmental adaptation rather than extensive evolution. Furthermore, because they are similar animals, even if they are not actually related, they are both similar kinds of amphibians. It makes sense from a design standpoint that they would have similar developmental features, but the aquatic variety simply hatches earlier in the process.
- Here is yet another example of using labeling to make something look more friendly to universal common descent evolution than it really is. The label of gill like or gill slits is used, sticks in the minds of those who hear it and it then becomes evidence for universal common descent, once again circular reasoning. Ultimately, these are just developmental structures that develop into different structures within each Organism. Yes, and fish these folds become gills, but in other organisms such as humans, they become completely different structures within the head and neck.
So, even though evolutionists claim evidence from embryonic development, the claims are based on a combination of friendly labeling and similarities in the early stages of structures that do not necessarily have any relationship. There is nothing within any example that has ever been claimed where the structure is non-functional, and in some cases, even the genes involved are completely different. In some cases, labeling and the use of Ernest Heckles’ debunked embryo chart make for better propaganda than science.
