Lecture #9—Evidence from Anatomy and Embryology This lecture continues describing evidence showing that evolution has occurred. The anatomy and embryology of animals are two topics that were well studied even in ancient times. The trends that are obvious even to early scholars were hard to explain with the Creation Model, except to say that the Creator simply designed organisms this way. The Evolution Model, however, clearly predicts that such trends should occur. Anatomical Principles: The concept of homology is critical to understand. Closely related organisms have similar structures which they inherited from their common ancestor (e.g. the skeleton of vertebrates are very similar). So we see that the forelegs of birds, mammals, reptiles, amphibians, and some fish all have the same pattern (humerus, ulna, radius, carpals, metacarpals, and phalanges) The Creation Model which says these animals are separate creations does not explain this similarity, but the Evolution Model does; the animals all have a common ancestor that had this bone arrangement. Superficial similarities in appearance that are not homologous (i.e. they have not inherited the structure from a common ancestor) are called analogous structures or homoplasies. An example would be the bat wing and the insect wing; they are built very differently and have evolved separately. It is important to know that the fossil record shows this evolutionary sequence: Consequently, when we study the anatomy of these animals we should expect to find trends that reflect this temporal sequence. Thus, we see this in the circulatory system (heart) where fish have a 2 chambered heart, amphibians 3, reptiles 3.5, and birds and mammals 4. Respiration trends are clear: fish have gills, amphibians have gills and lungs, reptiles have simple lungs, and birds and mammals have complex lungs. You should be able to describe this in some detail. are anatomical structures that do not appear to have a Vestigial Structures function or have a reduced one. This does not make sense to believers in the
Lecture #9—Evidence from Anatomy and Embryology This lecture continues describing evidence showing that evolution has occurred. The anatomy and embryology of animals are two topics that were well studied even in ancient times. The trends that are obvious even to early scholars were hard to explain with the Creation Model, except to say that the Creator simply designed organisms this way. The Evolution Model, however, clearly predicts that such trends should occur. Anatomical Principles: The concept of homology is critical to understand. Closely related organisms have similar structures which they inherited from their common ancestor (e.g. the skeleton of vertebrates are very similar). So we see that the forelegs of birds, mammals, reptiles, amphibians, and some fish all have the same pattern (humerus, ulna, radius, carpals, metacarpals, and phalanges) The Creation Model which says these animals are separate creations does not explain this similarity, but the Evolution Model does; the animals all have a common ancestor that had this bone arrangement. Superficial similarities in appearance that are not homologous (i.e. they have not inherited the structure from a common ancestor) are called analogous structures or homoplasies. An example would be the bat wing and the insect wing; they are built very differently and have evolved separately. It is important to know that the fossil record shows this evolutionary sequence: Consequently, when we study the anatomy of these animals we should expect to find trends that reflect this temporal sequence. Thus, we see this in the circulatory system (heart) where fish have a 2 chambered heart, amphibians 3, reptiles 3.5, and birds and mammals 4. Respiration trends are clear: fish have gills, amphibians have gills and lungs, reptiles have simple lungs, and birds and mammals have complex lungs. You should be able to describe this in some detail. Vestigial Structures are anatomical structures that do not appear to have a function or have a reduced one. This does not make sense to believers in the