How do you measure evolution?

Simple.

1. Take a population of organisms. Say, for instance, fruit flies or bacteria.

2. Measure the frequencies of a set of well-defined inherited traits in this population. In other Words, select some properties you know are passed on from one generation to the next, and count how many individuals in the population have this property.

3. Wait until one or more generations have passed.

4. Repeat step 2.

5. Note the difference between the frequencies measured in steps 2 and 4. This difference is called 'evolution'.