39. Fossil inside the body
Anatomy teaches the shape of the body. However, teaching only the shape of the body is not fun but teaching why the body is shaped this way is the fun part. Teaching the ¡°why¡± part is where comparable anatomy, embryology, and evolution study come in. Comparable anatomy studies how human differs from animal, embryology studies how human is transformed inside maternal placenta before birth, and evolution study studies how human has changed from ancestors who lived thousands of years ago.
Let¡¯s take coccyx as an example. <Anatomy> Human has one coccyx below sacrum, and it is palpable. <Comparable anatomy> Other mammals and reptiles have many coccyx and can move their coccyx. <Embryology> Humans also used to have many coccyges inside the maternal placenta. The number of coccyx was reduced to one as the tail disappeared. <Evolution study> The ancestors of human must have had many coccyx like monkeys.
Let¡¯s take heart as another example. <Anatomy> The human heart has four rooms. Oxygenated blood flows through the left atrium and left ventricle. Deoxygenated blood flows through right atrium and right ventricle. Like so, the human heart is composed two atriums and two ventricles preventing the blood from mixing. <Comparable anatomy> The heart of a fish is composed of one atrium and one ventricle allowing the blood to mix. <Embryology> The human heart is made up of one atrium and one ventricle at birth, but later becomes two atriums and two ventricles. In the case of congenital anomaly, operation must be done to form two atriums and two ventricles. <Evolution study> The heart of human ancestors must have had one atrium and one ventricle like fish.
Reading up to now, one might notice something. Comparable anatomy, Embryology, and Evolution study are all related. Comparable anatomy and evolution study are related in this way. ¡°Studying how humans and animal look different lets us know how humans have evolved.¡± This means that the human ancestors are animals. This is the evolutionary theory that creationists disapprove.
Embryology and evolution are also related. ¡°The transformation of human fetus enables us to predict how humans have evolved.¡± This is also a part of the evolutionary theory, and there are many more examples of this theory.
First, a human being originates from a single cell, a zygote made from a sperm and an egg. Therefore, the human ancestor far back must have been a single-celled organism. Second, human at the beginning had a small cerebrum. Therefore, the human ancestor far back must have been dumb. Third, human lived inside the amniotic fluid inside the mother¡¯s uterus. Therefore, the human ancestor far back must have lived in water. Fourth, human at the beginning had webbed hands and feet. Therefore, human ancestors far back must have lived on water like frogs and ducks. Fifth, humans at the beginning had short arms and legs. Therefore, human ancestor far back must have walked on four limbs like a dog. Babies today have short limbs and crawl, which makes me think that stages of development are related with stages of evolution.
In an anatomy lab, there are structures related with comparable anatomy, and embryology. For example, appendix is large and has a function in digesting food in vegetative animals. However, in humans, the appendix is small and has no role in digestion. Therefore, it is okay to remove the human appendix and we call this appendicitis. At the beginning, the human head and neck has gill like fish, and the external auditory meatus is the trace of this. At the beginning, the human¡¯s upper lip was divided like that of rabbit or cat, and philtrum is the resulting remnant.
¡°Structures related to comparable anatomy and embryology are fossils in the human body.¡± I can talk about the human ancestors who lived ages ago to explain this statement. It works the same way as a paleontologist instructor shows fossils in a natural history museum, or the same way as a History instructor shows artifacts of our ancestors. Anatomy lab turns into Nature History museum or museum if anatomy is taught together with comparable anatomy, embryology, and evolution study. Anatomy is a fun subject.