Comparative embryology
Comparative Embryology is the branch of embryology that compares and contrasts embryos of different species. It is used to show how all animals are related. Many things are compared, whether or not the organism has a notochord or whether or not it has gill arches. Many components go into Comparative Embryology, and much information about the developmental similarities between species can be taken from its study, which many conclusions can be drawn.
History
The first known person to study of embryos, was Aristotle. He observed different embryos and studied how different animals, who develop in different manners, such as by egg or by live birth, develop differently. He saw that there were two main ways that the egg cell divides. The first way was holoblastic, or where the whole egg divides and becomes the creature, and meroblastic, or where only part of the egg becomes the creature. This was the most comparative embryology had come until the invention of the microscope. Many people contributed to the field of comparative embryology. People from Ernst Haeckel to Charles Darwin to Aristotle have contributed to this field. They noted how different embryos change during development.
Misconceptions
In early years of comparative embryology, many erroneous theories have surfaced. One theory by Ernst Haeckel, a German biologist and philosopher, stated that all organisms go through a re-run of evolution while in development. He believed that to get to a mammal, an embryo first had to be a single-celled organism, then evolve into a fish, then an amphibian, then a reptile, then a bird, and finally reach a mammal. While this theory was widely accepted as the norm, it was disproved many years later.
Goal
The goal of Comparative Embryology is to make sense of how an embryo develops, and of how all animals are related. Comparative embryology also helps to prove evolution, in the sense that all vertebrates develop similarly. The conclusion is that all vertebrates must have a common ancestor.
See also
References
- Comparative Embryology Retrieved 5/21/14
- Embryology Retrieved 5/21/14
- Comparative Embryology: The Vertebrate Body Retrieved 5/22/14
- Embryology Retrieved 5/22/14
- Evidence for Evolution Retrieved 5/22/14
- Comparative Studies Insights Retrieved 5/23/13