Evolution Keeps Reinventing The Appendix

The once thought useless human appendix has evolved at least 29 times and been lost a maximum of 12 times, yet evolution keeps bringing it back. In a comparative study of mammal species, researchers mapped when the appendix appeared, disappeared, and then re-emerged across multiple evolutionary lineages. They found that once the appendix evolves, it almost never vanishes completely and tends to show up again in different branches of the mammal family tree.

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