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Top 10 Useless Limbs (and Other Vestigial Organs)



In Charles Darwin's On the Origin of Species (1859) and his next publication, The Descent of Man (1871), he referred to several "vestiges" in human anatomy that were left over from the course of evolution. These vestigial organs, Darwin argued, are evidence of evolution and represent a function that was once necessary for survival, but over time that function became either diminished or nonexistent.

The presence of an organ in one organism that resembles one found in another has led biologists to conclude that these two might have shared a common ancestor. Vestigial organs have demonstrated remarkably how species are related to one another, and has given solid ground for the idea of common descent to stand on. From common descent, it is predicted that organisms should retain these vestigial organs as structural remnants of lost functions. It is only because of macro-evolutionary theory, or evolution that takes place over very long periods of time, that these vestiges appear.

The term "vestigial organ" is often poorly defined, most commonly because someone has chosen a poor source to define the term. The Oxford English Dictionary (OED) defines vestigial organs as organs or structures remaining or surviving in a degenerate, atrophied, or imperfect condition or form. This is the accepted biological definition used in the theory of evolution.

In the never-ending search for scientific truth, hypotheses are proposed, evidence is found, and theories are formulated to describe and explain what is being observed in the world around us. The following are ten observations of vestigial organs whose presence have helped to flesh out the structure of the family tree that includes every living creature on our planet.
-- Brandon Miller

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Just because we can survive without these "vestigials" doesn't mean they don't still play a role, however minor it might be. We can survive without a gall bladder, but it definitely has a role to play. A little more research instead of relying on old assumptions might give different results.

Barbara Fitzpatrick wrote:Just because we can survive without these "vestigials" doesn't mean they don't still play a role, however minor it might be. We can survive without a gall bladder, but it definitely has a role to play. A little more research instead of relying on old assumptions might give different results.

The gall bladder isn't on the list. And: an organ can be vestigial even though it still "plays a role." A little more research instead of relying on old assumptions might give different results!

DAR
Speaking of gall bladders... I just talked to a friend today who just had his gall bladder removed a couple months ago (non-emergency). He didn't have insurance and it cost him $12,000. He said it cost $3,000 just to rent the surgery room for the one hour needed. And that was a "discount price" because he paid cash.

D.

Barbara Fitzpatrick wrote:Just because we can survive without these "vestigials" doesn't mean they don't still play a role, however minor it might be. We can survive without a gall bladder, but it definitely has a role to play. A little more research instead of relying on old assumptions might give different results.

The gall bladder doesn't fit even one of the three descriptors in the OED definition. In many, many classes of biology (including evolutionary biology) and biochemistry, I have never heard the gall bladder called vestigial. We can also survive without, say, hands, but that doesn't make them vestigial...

A human vestige that I didn't see on the list (probably because it isn't well known but is a dynamite example) is the plantaris muscle. In tree-dwelling mammals, the plantaris muscle extends from the back of the knee, under the heel, and under the foot. It allows these mammals to "grip" with their feet. In humans, however, the muscle has extremely little motor function, is often atrophied from disuse, sometimes simply disappears into the Achilles tendon, and occasionally is altogether absent.

Savonarola wrote:...(dynamite example) is the plantaris muscle.

DAR
Excellent.