Gaby
Our bodies are like museums of evolution. We walk on two legs because our common ancestor evolved that trait millions of years ago. Yet we still carry organs and functions that have outlived their original purpose—some of which we casually call unnecessary.
Take the appendix, for example. Once it played a major role in digesting plant matter, but Charles Darwin argued it had become redundant as our diet changed.
Wisdom teeth helped ancient humans chew raw roots and tough meat, but today they’re often nothing more than a dental complication because our food is largely processed.
And here’s another example that might give you chills: our ancestors used to fluff up body hair to protect against cold and predators. Now, excess hairiness is more likely to be the butt of a joke.
Why do vestigial body parts and functions persist?
Probably because they don’t harm us, says Matthew Ravosa, director of the Center for Functional Anatomy and Evolution at Johns Hopkins University School of Medicine.
Some organs have been repurposed as environments, behaviors, and selective pressures changed. The appendix is a prime example, Ravosa added. Calling the appendix harmless would be an exaggeration, however.
The appendix, once thought to be vestigial, may now play a role in gut health by helping the immune system combat pathogens. It contains a high concentration of immune tissue and beneficial bacteria that can help restore the gut microbiome after illness or antibiotic use. That evidence has challenged the long-held view that the appendix is useless.
It isn’t always clear which body parts are truly vestigial and which still serve a function, even if that function has shifted. Still, we’re increasingly seeing people born without body parts once considered common. Research cited by Popular Science shows roughly 35 percent of people are now born without wisdom teeth.
Meanwhile, the palmaris longus muscle (a muscle in the forearm) shows up in some people and not in others. It once helped with climbing and grasping, but today it’s functionally unnecessary for most tasks. Some people are born without it, and its absence does not affect grip strength.
As our diet, medical care, and technology continue to change, are we on the verge of losing even more body functions? As with many questions about the future, there’s no clear answer.
“There’s no sign we know what awaits us in the future,” Ravosa says. “The pace of technological change that can influence evolution is so rapid that everything is far less predictable than you might think.”
“We learn about vestigial organs when we look back,” he added. “We’ll just have to sit and watch, because we can’t predict the future.”
