Characteristics are of two types namely, homologous characteristics or analogous characteristics.
• Homologous characteristics are organs that have the same basic structure and origin, but different functions.
For example, mammals, birds, reptiles and amphibians have four limbs with the same basic limb layout because they have inherited the limbs from a common ancestor. These limbs have been modified to perform different functions.
• Analogous characteristics are organs that have different structures and are of different origin, but perform same functions.
For example, the design of the wings of bats and the wings of birds look similar because they have a common purpose – to fly.
