Useless Body Parts: Vestigial organs
Why have humans and other animals stopped using certain organs and functions which were once crucial for survival?
Charles Darwin is one of history’s most famous naturalists. Living in the 19th century, he became celebrated for his theories on evolution. In his seminal work On The Origin Of Species he described how similar animals were likely to be related by common ancestors, rather than be completely unrelated. As subsequent generations are born, traits and features that did not bring a survival benefit to that species were eliminated. That, in a nutshell, is the theory of evolution.
As a consequence, some organs and traits left in the body lose their function and are no longer used. This applies to modern human beings as much as other creatures; some of our physical attributes and behavioural responses are functional in other animals, but they do not seem to be of any benefit to us. These evolutionary remnants that no longer serve any purpose are called vestigial organs, though this can apply as much to behaviour and other body structures as it does to actual organs.
Evolution has also adapted some existing features to help us in new ways, in a process known as exaptation. For example, birds’ wings not only help them to fly but keep them warm too. These changes in function may take thousands of years to develop, and in some cases the original role is eventually eliminated from subsequent generations altogether
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This article was originally published in How It Works issue 56
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