Last updated: February 2, 2026
Anatomical features in the human body interpreted as vestiges of evolutionary history.
Vestigial structures are anatomical features or behaviors that are retained during the process of evolution in a given species, but have lost most or all of their original function. While they may have served a purpose in the organism's ancestors, they are now often reduced in size or complexity.
These structures are not necessarily useless; some may have adapted to new functions or retain minor roles. Within evolutionary theory, they are considered significant evidence for evolutionary change over time and common descent.
Vestigiality points to features that were functional in ancestral species but are no longer essential (or functional at all) in the current form, yet persist due to inheritance.
The vermiform appendix is a small, finger-like pouch attached to the large intestine. In plant-eating vertebrates, the corresponding organ (the cecum) is much larger and helps digest cellulose found in plants.
It's believed that the human appendix is a remnant of a larger cecum used by our herbivorous ancestors for digesting tough plant material.
While long considered useless and prone to infection (appendicitis), some recent research suggests the appendix might serve as a reservoir for beneficial gut bacteria or play a minor role in the immune system. However, its removal does not cause significant long-term health problems, indicating it's not essential for survival or normal function, fitting the definition of vestigial.
Wisdom teeth are the final set of molars that typically emerge in late adolescence or early adulthood. For many people, they cause problems because the modern human jaw is often too small to accommodate them.
Our ancestors had larger jaws and a coarser diet that required more chewing power and led to more tooth wear. These extra molars were likely beneficial for processing tough foods like roots and raw meat.
Changes in diet (softer, cooked foods) and potentially changes in jaw size during human evolution have made these third molars largely unnecessary and often problematic, leading to impaction, crowding, and infection.
The coccyx is a small, triangular bone at the base of the spine, formed by the fusion of several vertebrae. It's the remnant of a tail possessed by our primate ancestors.
Tails are used by many mammals for balance, communication, and swatting insects. While humans lost the external tail, the underlying bony structure persists.
Although it's a vestige of a tail, the coccyx isn't entirely useless. It serves as an attachment point for several muscles, tendons, and ligaments of the pelvic floor, providing support for pelvic organs.
Rarely, infants are born with a short, soft-tissue tail extending from the coccyx (a human tail), a condition known as an atavism, which further highlights this evolutionary remnant.
Attached to hair follicles are tiny muscles called arrector pili. When these muscles contract, they cause the hair to stand on end, resulting in what we call goosebumps.
In our furrier ancestors, erecting the hairs served two main purposes:
Since modern humans have significantly less body hair, goosebumps provide negligible insulation and have little effect on our appearance. They remain as a physiological reflex inherited from our ancestors, triggered by cold or strong emotions (like fear or awe).
Vestigial structures are considered evidence for evolution, as they demonstrate continuity between modern organisms and their ancestors.
The human body contains numerous examples of structures considered vestigial: anatomical features that appear to reflect ancestral forms. Examples include the appendix, coccyx, wisdom teeth, and arrector pili muscles.
These structures are interpreted within evolutionary theory as inherited traits that have diminished in function compared to their roles in ancestral species. Some retain minor functions, while others serve little apparent purpose in modern humans.