As you will know, we are descended from apes, but even before that our very early ancestors were almost certainly fishy and the legacy of our aquatic past can be found in the modern human body — and specifically, when things go wrong.
Roughly 370 million years ago when our very great, great grandparents shimmied ashore, fins became limbs and we acquired the ability to breathe on land as well as under water.
But there was a price to pay: hernias, hiccups and even (for some) an extra finger or toe.
Common triggers include guzzling fizzy drinks and eating too much — this distends the stomach, irritating the diaphragm, which contracts
I was thinking about this a few days ago after a really bad case of the hiccups.
Hiccupping occurs when you get sudden, involuntary contractions of your diaphragm, a big sheet of muscle that lies horizontally just below your lungs.
This makes you breathe in very quickly, which in turn snaps your vocal cord shut, making the ‘hiccup’ sound.
Common triggers include guzzling fizzy drinks and eating too much — this distends the stomach, irritating the diaphragm, which contracts.
Everyone has their own DIY remedies for hiccups, including bending over and drinking from the wrong side of a glass of water or getting a friend to jump out and try to scare you. If those techniques don’t work, and they probably won’t, then you could try a handful of ice cubes pressed against the side of your neck.
This will disrupt the messages being sent along your vagus nerve, a major nerve which runs from your gut to your brain and which, among other things, causes your diaphragm to contract. Having sex may also help, as this stimulates the vagus nerve.
Indeed I came across a report in a medical journal from 2020 about a 40-year-old man who’d hiccupped continuously for four days and was cured by having sex with his wife.
Or you could try simply holding your breath. Breathe in, then breathe out and try to hold as long as you comfortably can . . . I can do a minute but for many people it might be shorter. If that doesn’t work the first time, then do it again.
Using a paper bag to breathe in and out for 20-30 seconds will also do the trick.
Why does that work? Well, holding your breath drives up carbon dioxide levels in your blood, which in turn dials down a circuit in your brain called a central pattern generator, and that stops the hiccups. We have lots of these circuits in our brain and they help regulate different unconscious behaviours, such as walking, swimming, breathing, or chewing.
We seem to have inherited the particular central pattern generator that sometimes triggers hiccups from a distant fishy ancestor. When they first came out of the seas, they had gills, so they could breathe under water, but would also have needed lungs, and been able to readily switch between the two. Tadpoles, which are very distantly related to us, have a circuit in their brains which allows them to do this, and which is dialled down by carbon dioxide.
The reason that men are particularly prone to hernias is because our sexual plumbing is remarkably odd
We have a similar circuit, perhaps so that when we first begin to suckle milk we can safely drink and breathe at the same time. The downside is it occasionally misfires, triggering hiccups. Hiccupping is normally short lived, and more annoying than dangerous.
There is another design fault in humans, again inherited from our fishy ancestors, which can lead to a condition which is far more inconvenient, painful and sometimes even fatal: an inguinal hernia. Around 25 per cent of men, and just 2 per cent of women, will develop this at some point.
It occurs when part of your intestines pushes through a weakness in the muscle wall, causing a bulge, somewhere near your groin.
You know it’s a hernia because though coughing or straining makes it appear, it can normally be pushed back or disappears when you lie down. You should see your doctor if you develop one, and experience any sudden, severe pain, difficulty emptying your bowels, or you cannot push the hernia back in — this can be a medical emergency.
The reason that men are particularly prone to hernias is because our sexual plumbing is remarkably odd.
Sperm are produced and stored in our testes, but then have to travel through a series of tubes to the penis — and instead of going straight there, these tubes go up towards your waist, loop over your pelvis, then have to travel all the way back through the pelvis to the penis.
This long and meandering journey leads to weaknesses in the abdominal wall, and hernias. Why does it go this circuitous route? Because your testes start life up in your chest, near your heart, and then later travel south.
And they start up there because that’s where fish keep their testes.
Another odd, but much rarer thing that happens, and which may be linked to our fishy origins, is polydactyly — people who have more than five digits on each hand.
A few years ago I filmed with a lovely Brazilian family who all have an extra, fully working finger, as well as six toes.
No one knows exactly how this occurs, but one theory is that this is a throwback to our past, when the first amphibians that crawled on land had anywhere between six and eight digits on each limb.
Over time, their descendants lost a few, so that most of us have to get by with just five. The Brazilian family I met were all immensely proud of being different, and they assured me there were lots of benefits to having an extra finger, including being better at computer games. Unlike hiccups and hernias, extra digits can be useful.
My kids recently gave me some wireless headphones, and I’m totally addicted to them. But I’ve also just learnt that using headphones, or earbuds, for more than an hour a day, particularly at a volume over 70 decibels (roughly the level of a vacuum cleaner) is likely to put my hearing at risk. And that matters as loss of hearing increases the risk of dementia. So keep the volume down to a level where you can still hear someone talking to you.
It’s time to retire the idea you can be ‘fat but fit’
Can you be fat but fit? In other words, can you be extremely overweight but still be healthy? I was recently on a radio programme discussing this with someone who argued passionately that weight shouldn’t matter and that we are overly obsessed with numbers on a scale.
Now I agree that scales alone are unreliable, that fat shaming is awful and that telling other people to lose weight never works. But the bad news for the very overweight is that this does matter and even if you’re currently healthy, you’re unlikely to stay that way. That’s according to lots of research, including a recent study, published in Diabetologia, the journal of the European Association for the Study of Diabetes, by researchers from Glasgow University. They looked at data collected from more than 381,000 men and women
Their findings were shocking: after 11 years people who were obese (ie with a BMI over 30), but healthy at the start of the study were 420 per cent more likely to develop type 2 diabetes, 76 per cent more likely to suffer heart failure, and nearly 20 per cent more likely to have had a heart attack or stroke compared with people with a healthy weight.
On the basis of these results, Dr Frederick Ho, who led the study, thinks the term ‘metabolically healthy obesity’ (ie what many might call fat but fit) should be retired.I would recommend keeping an eye, as I do, not only on your weight, but your waist size, your blood sugar levels and blood pressure.
And if any of those numbers are high, or rising, do something about it.