Embryological Evidence of Evolution — Summary & Examples

(Video) Evidence for Evolution

by Teacher's Pet

Embryology is the study of, you guessed it, embryos. An embryo is made from the first divisions of a fertilized egg and sperm cell. During early development, you wouldn't be able to tell the difference between a cat, a human, or a bat embryo.

Scientists have figured out that species who evolved from a recent common ancestor have very similar patterns of embryonic growth and development. The same groups of cells develop in the same order for these species despite the fact that adult forms of the species look very different. In this video, Teacher's Pet explains the embryological evidence for evolution.

How Can Embryos Be Used to Show Evidence of Evolution?

Embryology, or the study of embryos, can help us find plenty of evidence to support the theory of evolution. For example, vestigial structures such as tails or gills in humans can be found in embryos early during their development.

Another major piece of evidence is Hox genes. Hox genes control the development of an organism from head to tail. Hox genes are similar in most multicellular eukaryotes, even between insects and humans. You can use the small changes in Hox gene DNA to see where different species diverged from their common ancestor.

Comparative Embryology vs. Comparative Anatomy

(Video) What Is the Evidence for Evolution?

by Stated Clearly

Embryology offers an inside look at the development of an organism. An embryo of an organism is the fertilized egg as it goes through the processes of development that is specific to that species. When looking at how the animal develops from an embryo to an adult, you can compare the processes with those of other organisms to help determine evolutionary similarities.

Embryological Evolution

An embryo goes through a number of stages before it develops into a fetus and eventually into a living offspring. Studying the structures that develop during an embryo's various stages of growth is called embryology and can be used to show the genetic similarities that suggest certain patterns of evolution.

Most embryos look similar in their early stages, but as they develop, the differences between species become more obvious. Embryos of organisms that have a closer genetic relationship to one another tend to look similar for a longer period of time since they share a more recent common ancestor.

In early embryonic stages, embryos will often form structures that will not be present in the organism's final form.

For example, human embryos develop a tail in the beginning stages of our development. However, further along in the process, certain genes kick in that absorb the tail cells, leaving us with a nub referred to as a vestigial tail. The development of this vestigial tail suggests that we had a tail at some point in our evolutionary history, but adaptations and evolutionary shifts made tails unnecessary for our survival.

Historic Theories

Early on, a major player in the progression of embryology was a German scientist named Ernst Haeckel. While studying vertebrate embryos, he came up with many (exaggerated) drawings to illustrate the biogenetic law (recapitulation theory). This was a theory stating that "ontogeny recapitulates phylogeny". In much simpler terms, this means embryos develop in a way that mirrors how their ancestors evolved over time.

Although this hypothesis was proven to be incorrect, it was still a major influential idea of the 18th century.