What evidence is there for evolution?

For IB Biology, there are three types of evidence for evolution you need to know: fossils, selective breeding and homologous structures.

Fossils are preserved remains or traces of organisms from the past – they include direct evidence like bones, teeth, shells, leaves etc. and indirect evidence like footprints, tooth marks. The fossil record shows that the features of organisms have changed over time. We can see this by dating the fossils to find out when each sample was from.

Selective breeding has shown that artificial selection can cause evolution – race horses, for example, have been bred for speed and are lighter, taller and quicker – these changes in traits and characteristics are examples of evolution.

Adaptive radiation is when organisms diversify from an ancestral species into many new ones – these species may have features that are similar in structure despite being used in different ways – these are homologous structures. One example is the pentadactyl limb which exists in a variety of species – mammals, birds, amphibians and reptiles all share a similar arrangement of bones in their appendages based on a five-digit limb. Human hands manipulate tools, whale and dolphin fins are adapted for swimming and bird wings are adapted from flying.