That's No Vestigial Organ, That's My Appendix
A study in the Journal of Evolutionary Biology finds that many more animals have appendixes than was thought, and that the appendix is not merely a remnant of a digestive organ called the cecum. All of which means that the appendix might not be so useless. Steve Mirsky reports
SUBSCRIBE TO Science Quickly
On supporting science journalism
If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
[The following is an exact transcript of this podcast.]
Two years ago, Duke University Medical Center researchers said that the supposedly useless appendix is actually where good gut bacteria safely hide out during some unpleasant intestinal conditions.
Now the research team has looked at the appendix over evolutionary history. They found that animals have had appendixes for about 80 million years. And the organ has evolved separately at least twice, once among the weird Australian marsupials and another time in the regular old mammal lineage that we belong to.
Darwin thought that only a few animals have an appendix and that the human version was what was left of a digestive organ called the cecum. But the new study found that 70 percent of rodent and primate groups have species with an appendix. And some living animals have a cecum and an appendix. If Darwin had known about species that had both organs, he probably would have revised his views of the appendix, the researchers note.
Ironically, it’s natural selection that keeps the human appendix from shrinking away completely. Because smaller ones are more likely to become infected. And keep your genes out of the pool.
—Steve Mirsky
Subscribe to Support Independent Journalism
Great science journalism requires human expertise, time, effort and creativity. And it costs money. That’s why I and the journalists here at Scientific American hope you’ll join our community.
When you subscribe, you are supporting staff and freelance journalists who are passionate about telling science stories that are true, important and compelling. Our editors and reporters are often experts in their fields, which means they understand the nuances of big discoveries and can untangle the breakthroughs from the hype. With a subscription, you are also supporting rigorous fact-checking to ensure the words we publish are precise and accurate. And you’re supporting original illustrations, graphics and photos that bring you closer to an advanced laboratory, an ice sheet in Antarctica or a space mission in orbit. You’re helping us craft other types of high-quality journalism as well: Our newsletters are carefully written, edited and curated by staffers you have or will come to know and love. Our Science Quickly podcast is based on original reporting, collaboration with editors and scientists and exacting production.
Subscriptions keep this engine running so we can continue to deliver thoughtful, rigorous and independent science journalism to you. In an era of viral misinformation, this work is crucial. If you value what we do, I hope you’ll consider joining us as a subscriber
