Losing body parts: could continuing human evolution spell the end for some “unnecessary” biological bits and pieces?

Are humans still evolving, or are we already the finished product, was the topic of this week’s Horizon – and feeling the back of my mouth where my absent wisdom teeth would normally go, I wondered whether these, and other body parts, are testament to humanity’s continuing evolution.

A central question at the heart of the programme presented by Dr Alice Roberts was whether, through our use of technology, we have isolated ourselves from natural selection.

As she said, “There is something that makes us very different from any other animals. Something that means that the normal rules of evolution may not apply to us.

“Tens of thousands of years ago, our ancestors began to protect themselves from the environment in a way that no other creatures have managed to do.

“They invented things that made life easier: shelters, tools, and other simple technologies that didn’t exist anywhere else in the natural world. So while polar bears evolved thick coats of blubber to cope with the cold, our ancestors made fires and wrapped themselves in clothes. By helping us adapt to new environments, did our inventions stop us evolving. Has all our technology sheltered us not only from nature but from natural selection itself?”

In other words, Dr Roberts asked, “Has our culture, our technology, stopped us evolving? Are we the same as the people that emerged in Africa 200,000 years ago?”

It’s a fascinating question, and as with most other Horizon programmes, it looked at both the arguments for and against the idea of continuing human evolution, including medical advances (and whether the cure will fundamentally prove more dangerous than the original disease – but that’s a whole other topic).

The programme looked at how Nepalese Sherpas in the Himalayan mountains, living in one of the most inhospitable enviroments in the world, have evolved a different circulatory system to cope with the low oxygen at high altitudes.

But what about other body parts, such as the appendix and wisdom teeth, which are arguably more trouble than they are worth? In the UK, 7% of people will have appendicitis at some point in their lives.

The most common causes of appendicitis, according to the NHS, are infection and obstruction (when something gets trapped in the appendix), although in many cases there is no obvious cause.

If left untreated, the appendix can burst, leading to potentially fatal consequences, and is therefore removed. However, as it says on their website, “Living without an appendix will cause no related problems”.

Although there is some debate about the usefulness of the appendix, with some scientists saying that it acts as a bacterial reservoir which can come in handy after losses during disease, the jury is still out on how truly important it is.

Likewise with wisdom teeth, it appears that more and more people are being born without their full set of four, and some (including me) without any at all (I’m past the age when wisdom teeth are likely to emerge, if all at – just as well, as there’s no more room at the inn).

However, it’s important to remember that traits, such as losing wisdom teeth, don’t evolve for the good of the species as part of some kind of overriding grand master plan – changes like these are said to be the product of random mutations.

There is genetic variation within species, so my lack of any wisdom teeth could simply be an example of this, rather than necessarily any indication of a continuing evolution that results in humanity no longer having those extra four pearly whites.

According to Darwin’s theory of evolution by natural selection, traits would only disappear if they hampered the survival of a species.

Biologist PZ Myers, also known as the blogger Pharyngula, argues that body parts, such as the appendix, which arguably don’t benefit, or significantly disadvantage, humanity, may not disappear at all, and “are retained as entirely neutral characters”.

He said: “I’m also unconvinced by the argument that retention of a feature for 80 million years is necessarily evidence of selection for a specific function.

“The fact that the appendix has an incidental function that can be useful to individuals in specific circumstances does not mean that the appendix isn’t a vestigial organ, nor does it necessarily mean that its retention has been selected for.

“That some modern human populations have significant mortality from diarrheal symptoms (from cholera, for instance) seems to me to be a relatively trivial factor in a study that shows persistence of the appendix over many tens of millions of years, especially when no evidence of differential survival by individuals having or lacking an appendix is known.”

Whether body parts like the appendix or wisdom teeth will be phased out through evolution is unclear, but given that they have stayed in humans for this long, without any concrete purpose, implies that we won’t be seeing the end of them any time soon.

Image courtesy of Flickr user assbach.
  1. Zorina

    you know human evolution is very interesting but I do believe technology contributes to the premise of human being. Technology has aloud us to take our self out of nature and create a whole different world. So although will live on earth we don't live in it. We have completely seperated our selves from mother nature but have the nerve to kill a mouse when it comes in our habbitat when in reality we are in theirs. Which is really ours to beging with. My views of this are influnce by a book I once read called Ishmael greatest book I ever read in my life.

  2. Zorina

    you know human evolution is very interesting but I do believe technology contributes to the premise of human being. Technology has aloud us to take our self out of nature and create a whole different world. So although will live on earth we don't live in it. We have completely seperated our selves from mother nature but have the nerve to kill a mouse when it comes in our habbitat when in reality we are in theirs. Which is really ours to beging with. My views of this are influnce by a book I once read called Ishmael greatest book I ever read in my life.

  3. Zorina

    you know human evolution is very interesting but I do believe technology contributes to the premise of human being. Technology has aloud us to take our self out of nature and create a whole different world. So although will live on earth we don't live in it. We have completely seperated our selves from mother nature but have the nerve to kill a mouse when it comes in our habbitat when in reality we are in theirs. Which is really ours to beging with. My views of this are influnce by a book I once read called Ishmael greatest book I ever read in my life.

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© Melanie Hall 2017