Summary
Reduced features retained from ancestors that have lost most of their original function, such as the human appendix.
In depth
Examples include the human appendix and tailbone, pelvic bones in whales and wings of flightless birds. These organs have lost most or all of their original function, although some retain a new minor function.
They are expected when function declines and selection is relaxed.
Vestigial does not mean useless: the human appendix may serve as a reservoir for beneficial gut bacteria, but is reduced compared with that of herbivores, and removal is generally tolerated. Other vestiges include wisdom teeth, the ear-moving muscles, goosebumps, and the eyes of cave fish and blind mole rats, which are covered by skin.
They are explained by reduced selection or by costs of maintenance: when a structure no longer benefits survival, mutations accumulate and it shrinks over time. Genetic vestiges, such as pseudogenes for smell receptors, are common in humans, which have about 400 working olfactory genes and many broken ones.
Example: some snakes and whales have tiny pelvic and limb bones, which show descent from four-legged ancestors.
Frequently asked questions
What is Vestigial Structures?
Reduced features retained from ancestors that have lost most of their original function, such as the human appendix.
Which area of biology covers Vestigial Structures, and how advanced is it?
Vestigial Structures is one of the 53 topics in Evolution. It is rated Beginner, so it suits learners who are starting out in biology. Related topics in this area include Homologous Structures, Common Ancestry, Analogous Structures.
Can you give an example of Vestigial Structures?
Some blind cave fish retain eye remnants under skin.
What should I learn before Vestigial Structures?
Vestigial Structures is a Beginner topic, so no earlier topic is required. Other Beginner topics in Evolution that pair well with it include Evolution, Natural Selection, Charles Darwin.
What topics are related to Vestigial Structures?
The closest topics to Vestigial Structures are Homologous Structures, Common Ancestry, Analogous Structures, Selective Sweeps. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Vestigial Structures?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Vestigial Structures. To practise the whole of Evolution, use the Evolution quiz.
How is Vestigial Structures different from Homologous Structures?
Vestigial Structures: Reduced features retained from ancestors that have lost most of their original function, such as the human appendix. Homologous Structures: Body parts with similar structure from a common ancestor but different functions, like a human arm and bat wing. Read both side by side and note what each one explains.
How should I study Vestigial Structures step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Homologous Structures and explain the difference aloud. Finally, take the Evolution quiz and come back to this page for any question you miss.