Evidence for Evolution - Anatomy & Geography
Biology: IB Diploma Higher Level, topic 3.2.2
The Evidence for Evolution by Natural Selection
The theory of evolution by natural selection has evidence from multiple scientific fields. This includes geological, molecular, biochemical, and physical evidence.
Anatomy and embryology
- An example of anatomical evidence for evolution is the presence of structures in organisms that share the same basic form.
- For example, the bones in the appendages of a human, dog, and whale all share the same overall construction resulting from their origin in the appendages of a common ancestor.
- Over time, evolution led to changes in the shapes and sizes of these bones in different species, but they have maintained the same overall layout.
- Scientists call these synonymous parts homologous structures.
Vestigial structures
- Some structures exist in organisms that have no apparent function at all, and appear to be residual parts from a past common ancestor.
- These unused structures without function are called vestigial structures.
- Examples of vestigial structures include wings on flightless birds, leaves on some cacti, and hind leg bones in whales.
Geographical evidence
- The geographic distribution of organisms on the planet follows patterns that are best explained by evolution in conjunction with the movement of tectonic plates over time.
- Broad groups that evolved before the breakup of the supercontinent Pangaea (about 200 million years ago) are distributed worldwide.
Test yourself on Evidence for Evolution - Anatomy & Geography
Which of the following is an example of a homologous structure?