Evidence of Evolution

Evolution typically occurs over many years, at a pace that is often difficult for us to observe in real time. Yet organisms share similarities that are due to common ancestors - species that lived in th past that are not alive today.

If two species have many similarities, they likely share a recent common ancestor that also had those characteristics.
Anatomical Evidence refers to similarities in body parts -anatomy.
- This can include fossil evidence and embryological similarities
Genetic Evidence is the shared DNA between two species
- Mutations build up in genes and non-coding DNA over time and is passed on from generation to generation.

Anatomical Evidence

Body structures can show similarities, but they can also be misleading.

Homologous Structures - similar features due to a common ancestor of both species.

Vestigial Structures - small useless structures that are the remains of a useful structure in an ancestor.

Analogous Structures - similar features favored by the environment that are NOT due to a common ancestor.

Genetic Evidence

DNA is passed on from generation to generation. Most genes control the development of proteins that are essential for life, but mutations occur randomly and can be passed on to offspring.

Important genes don't tolerate mutation very well.
- Silent mutations that code for the same amino acid are very rare
- Defective proteins can make it harder to survive and reproduce, thus they don't get passed on.
The DNA in between genes is much more likely to accumulate mutations.
- Natural selection can't act on DNA that doesn't code for proteins.
- This "Junk DNA" often has many more differences when you compare the DNA of two individuals.