Not a fact anymore

The human appendix is a useless vestigial organ with no biological function.

What we know now

The appendix contains abundant immune tissue and may help maintain or restore gut microbial communities. It is not essential, and most people can live normally after it is removed.

Why it changed

Research in anatomy, immunology, and the microbiome showed organized lymphoid tissue and distinctive microbial communities in the appendix, replacing the simple idea of a useless remnant.

Status
Superseded
Category
Medicine
Accepted for
≈122 years
Accepted approximately
Late 19th through much of the 20th century
Changed approximately
Late 20th century–present

In evolutionary biology, “vestigial” does not necessarily mean completely useless. A structure can lose much of an ancestral role while keeping or gaining other functions.

Some proposed microbiome functions remain under study. The correction is to the absolute claim that the appendix does nothing.

Evidence

Sources and what they establish

Current evidence

Historical context

Related entries

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