We can get a glimpse into an organism's evolutionary history through embryology. As an illustration, consider terrestrial vertebrates, which include mammals, birds, amphibians, and reptiles. There are numerous parallels between fish embryos and other animal embryos when we examine the early stages of the development of various groups of animals. All of these animal groups have gill arches in their developing embryos. These develop into functioning gills in fish embryos. They go on to develop into the morphological structures that make up our ears in the majority of terrestrial animals. This helps us understand how certain animal traits may have evolved from more basic ones. Cases like these add to the body of evidence showing that lobe-finned fishes are the ancestors of terrestrial mammals.
Embryology offers no proof. The descriptive study of embryos is known as embryology. It has been discovered that embryos from all species have parts that should naturally belong to less advanced organisms. By the time the embryo develops into a fully formed live being, those structures have either vanished or changed into something more adapted to the particular environment. Because the ancestors of the species whose embryo we are investigating truly possessed such qualities and made use of them, we refer to them as atavistic features, from the Latin term for forefather. These traits are numerous. I'll name one. An embryonic human resembles an embryonic monkey almost exactly, down to the tail. Human genes guarantee (nearly invariably) that the tail resorbs, leaving just a little remnant with five tail bones, the coccyx, whereas the genes of the monkey ensure that it is still present at birth. Human embryos, as well as monkeys and many other animals, feature fish-like gill clefts. In our situation, they were born as more beneficial organs.
Therefore, embryology detects phenomena that call for justification. They would just be bizarre if they weren't. Every creature's embryology may be thoroughly examined to build a comprehensive picture that is perfectly compatible with evolution. That is but one piece of the puzzle of findings and information that support the hypothesis (i.e., explanation) of evolution.
To be fair, I should point out that there are alternative hypotheses that might account for the embryological findings as well as the variety and at the same time linear similarity of all living things, whether ancient and modern. Accepting these alternative explanations allows you to forget about learning anything and skip over years of fruitless inquiry in the fields of embryology, paleontology, biology, and anatomy. It also greatly simplifies the process of comprehension. All you need to do is put your trust in the scientifically illiterate authors from two centuries ago who, through no fault of their own, may have known nothing about biology, anatomy, or physiology because those fields didn't even exist at the time. As a result, they could have observed nothing and conducted zero research.
That does however require you to understand that the tens of thousands of scientists who have carried out all the work over the past 200 years have all been frauds, and that there is a massive global conspiracy devoted to disseminating lies and misinformation in order to enrage a small American sect known as creationists. even if the majority of those scientists practice religions similar to those of everyone else. Why? It must be to exact revenge on those hateful Christians, who have undoubtedly caused them terrible, unnamed suffering.
