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Anthea Rowan

I don’t have mine. Chances are, you don’t have yours either – but we’re none the worse off without it. That would be the appendix, often referred to as a useless organ.
We needed it in the past, before we evolved into the humans we are today. Plant-eating animals still need theirs to help digest food, but it’s not a working part of our digestive tract.
The spleen: why it matters, how it works and ways to keep it healthy
The appendix isn’t the only useless organ; we have almost a dozen that have become obsolete for the same reason: evolution has rendered them redundant. Here’s a list of some of the less obvious ones.
The palmaris longus muscle is a muscle that runs from the wrist to the elbow. If you rest the back of your wrist on a table and link your thumb to your little finger, you may notice a band of muscle pop up that runs towards the inside of your wrist. About 16 per cent of humans don’t have one.

 
It was once, scientists think, significant in helping early humans with their grip but when we began to walk upright, we did not need to hang on so hard – because we weren’t swinging through trees – and the muscle no longer served a purpose.
Those people who do still have the muscle have a grip no stronger than those without it. Its does still have one use: tendon grafting; it can be chopped out and relocated elsewhere in your body without affecting the movement of the hand or wrist.
Have you ever wondered what makes goose bumps? Ever noticed bald men don’t get them on the tops of their heads no matter how cold they are? Goosebumps are created when the tiny arrector pili muscle fibres around hair follicles contract.

When we were hairier – when we were swinging through trees using our appendix to digest leaves and our palmaris longus muscle to hang on tight – we made that hair stand on end for two reasons: to keep warm and to look more frightening.
Our hair still stands on end when these little muscles react to cold or emotion.
The auricular muscles are another set of muscles that animals still use daily but which humans don’t need. These muscles control the visible part of the ear – but we’ve lost the ability to as we don’t need to prick our ears to sound, we can turn our heads as our necks have grown more flexible.
Some people can wiggle their ears as a party trick, but cock their ear to sound? Not so much. Your dog can, and your cat. But not you. Nor, interestingly, chimps.

The pyramidalis muscle, which is located in the lower abdomen, is – the clue is in the name – shaped like a triangle. Some people have two. Some have none. And you’re unlikely to know if you do own one unless you’ve had an MRI and thought to ask; it’s hard to tell otherwise.
The function of the pyramidalis, which is very small and tucked down near your groin if you have one (your gynaecologist might meet it if you’re a woman) is to help tense the linea alba, that long muscle that runs down the midline of the abdomen and which you can see on super sculpted people with ironing boards for stomachs. But it doesn’t do much except present as tender in some sportsmen and women who do have one.
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Human embryos develop a tail at between five and eight weeks of growth. Obviously you don’t see people wandering around wagging their tails, so we know that it disappears before a baby is born – the little stub that developed ends up as the lowest of our vertebrae, merging to form the coccyx, or tail bone. (And I know I have one of these, I fell badly on it once and it was excruciating).
Our ancestors had tails, but they shrank as we found ourselves walking upright.
Very, very rarely, babies are born with a little tiny redundant stump of a tail, which can be removed surgically.

The plica semilunaris, or third eyelid, is a fold of tissue found on the inside corner of your eye – next to the tiny bump you can see there. It looks a little like the membranes that some animals can draw across their eyes to protect them and help keep them lubricated – often especially evident in birds. Our little tiny leftover plica semilunaris is a vestigial hangover of the same thing.
Tonsils are a bit like your appendix in that both are only ever removed because they’ve become inflamed and infected thereby presenting a hazard to their host: you.
Some doctors still swear that, like the appendix, they serve a valuable function in fighting infection, but most would agree that when they’ve got to go, they’ve got to go. Nobody seems any the worse for wear in not owning a pair – certainly not the 500,000 children in the US who have them removed every year.

Like the appendix and the tonsils, sinuses are another non-vital organ. Sometimes people are born without sinuses and sometimes they have them surgically removed. They present as four pairs of air-filled holes behind the nose and around the eyes – you may have felt their painful presence when you’ve had a bad head cold, or they swell with sinusitis. They are pockets of nothing, so they make the head lighter and help the voice to resonate.
Doctors agree they do little for us and more for the hosts of bacteria and viruses that decide to take up residence in these nice warm, moist little caves, which is why they’ve been described as “Petri dishes for bugs in our head”.

As we continue to evolve, what else will become obsolete? We still have jaws, obviously, but they are much smaller than they were as our diet has become softer and more refined. Because our jaws are smaller, we battle to fit in all our teeth comfortably, so wisdom teeth are potentially on the way out, too.
And body hair – many of us strip most of it away – serves little function now, other than to form brows and the hair on our heads.


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Wellness

Eight useless body parts – sinuses, tonsils, appendix among them – that human evolution has left behind

C972EJ Throat Tonsils

HACR1G Illustration of the palmaris longus muscles.

Pyramidalis muscle Photo: HANDOUT [FEATURES 2018]

RB8BX8 SINUS ILLUSTRATION

E1JKT8 External anatomy of the human eye (with labels).

FXNM54 Cross section of skin showing hair follicle, sebaceous glands, sweat gland and arrector pili muscle structure, 3D illustration

Unlike dogs and cats, humans and our fellow hominids, chimpanzees, have lost the ability to cock their ears in response to sounds. The auricular muscles are still there, they just don’t work. Photo: AFP

Don’t kiss your health goodbye: all you need to know about mono, the virus that hits teens and young adults hardest

HBX44N Epstein-Barr virus (EBV), computer illustration. EBV, also known as human herpes virus 4, is 1 of 8 herpes viruses that infects humans. It is best known as the cause of infectious mononucleosis (glandular fever), but is also associated with some forms of cancer, including Burkitt's lymphoma. In both infections, the virus infects one type of white blood cell, the B lymphocytes. Infection with EBV is common and usually harmless; additional factors potentiate the development of more serious diseases.

Tina Ardon Photo: HANDOUT [FEATURES 2018]

F3HK0M Adult sisters in kitchen handing glass of rose wine

PP71H0 Young asian woman over isolated background feeling unwell and coughing as symptom for cold or bronchitis. Healthcare concept.

Infectious mononucleosis starts with symptoms including a sore throat and fever. Photo: Alamy

Why the liver is a multi-purpose marvel and how we can help keep it healthy

The liver is a multi-purpose organ crucial to good health, but liver disease is not easy to diagnose because symptoms are often not obvious. Photo: Alamy

Lifestyle

Health & Wellness

Knowledge

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The Human Body

Explainers

Organs


You may know about your appendix, but what about your auricular muscles or plica semilunaris?
These vestigial body parts all became obsolete as we evolved into hominids; so too will wisdom teeth and body hair in due course



You may know about your appendix, but what about your auricular muscles or plica semilunaris? These vestigial body parts all became obsolete as we evolved into hominids; so too will wisdom teeth and body hair in due course.


Medicine

Disease

The human body