Traditionally the appendix is the blockbuster of useless body parts – a leader in purposelessness ahead of wisdom teeth and the tailbone.
However, a new study suggests the appendix isn’t vestigial at all – and may serve an important biological purpose.
US scientists studied the timeline of the appendix’s evolution in humans by analysing gastrointestinal and environmental traits from 533 mammal species.
The researchers found the appendix has evolved independently over 30 times in separate species and “almost never” disappears from a lineage once it has appeared. Furthermore their findings contradicted previous hypotheses which have tried to link the appendix with dietary and environmental factors.
The researchers found appendixes were linked with higher concentrations of lymphoid tissue in the cecum – a pouch connected to the small and large intestines.
The scientists suggest the appendix thus may play an important role in the immune system as a secondary defensive organ. They said it could act as a “safe house” for helpful gut bacteria due to its high level of lymphatic tissue and concluded it evolves as part of a larger complex which includes the cecum.
“While these links between the appendix and cecal factors have been suggested before, this is the first time they have been statistically validated,” said the team from Midwestern University in their paper – published in the journal Comptes Rendus Palevol.
For a long time, as with other vestigial body parts, the appendix has been thought to have served a purpose for our primitive ancestors but is not necessary to modern humans. Furthermore the organ has a tendency to become inflamed – an ailment called appendicitis – with doctors often removing the organ altogether.
Those of us who have had their appendix removed shouldn’t be too concerned however, as doctors say serious or long term complications with its removal are rare. Whether or not this is due to other organs compensating for its removal is as yet unclear.