Show Me the Science with Luke O'Neill

Why do some people love wine, while others can’t stand it? Why did Covid strip food of its pleasure for so many? And how much of what we call “taste” is really happening in the nose, the brain, and even our memories?
This week's podcast takes on a listener-requested topic: the science of taste and flavour. Professor Luke O’Neill explains why taste is far more complex than the tongue alone, with up to 80% of flavour driven by smell and only around 20% by taste itself. He walks through the five core tastes — sweet, sour, salty, bitter and umami — and explains how specialised receptors in the tongue, nose, throat and even the stomach detect chemicals in food. These discoveries were so fundamental they led to Nobel Prizes.
The episode also explores how nerves shape flavour: why chilli feels hot, mint feels cool, and fizzy drinks tingle. Texture matters too. Creaminess, crispiness, and mouthfeel all shape how food is experienced. Vision and psychology play their part as well, from expectation bias to the power of nostalgia, famously captured by Proust’s madeleine.
Genetics turn out to be crucial. Some people find coriander tastes like soap; others find it fresh and citrusy. Some recoil from sprouts, broccoli, chilli or umami-rich foods, while others seek them out. Finally, Luke looks at how chefs have been quietly mastering this science for centuries, using fat to enhance flavour, stacking umami to build intensity, and manipulating texture and aroma to transform how food tastes.
This episode was prompted by listener requests from Stephen and Eoin. If there’s a science topic you’d like Luke to tackle next, you can email [email protected].

Ireland, like much of Europe, is in the middle of a serious flu outbreak. This week’s podcast focuses on why this year’s influenza wave is hitting so hard, who is most at risk, and what actually helps.
Professor Luke O’Neill explains why flu thrives in winter, spreading easily indoors where ventilation is poor. He outlines the classic flu symptoms — high temperature, severe fatigue, aches and pains, cough and runny nose — and why this strain is leaving many people bedridden for days rather than just mildly unwell. Flu is currently a bigger problem than Covid — widespread immunity has made Covid more benign, while influenza continues to evolve, throwing up new variants every winter.
The episode looks at who needs to be especially careful, and why flu season is such a concern for hospitals, with emergency departments under pressure and trolley numbers rising. Luke also discusses why this year’s vaccine has been less well matched than usual, after the virus mutated on its way from the southern to the northern hemisphere — and why it still matters.
And if flu symptoms do strike, Luke’s advice is simple: rest, stay hydrated, manage fever and pain, and don’t panic.

Every January, millions of us promise that this will be the year we finally change our habits. We’ll sleep more, stress less, move our bodies, eat better, learn something new, or finally tackle the clutter that’s been quietly judging us from the corner of the room. But by spring, most of those resolutions are long forgotten.
On this week’s podcast, Professor Luke O’Neill digs into what research really tells us about New Year resolutions — why we make them, why so many fail, and how we can dramatically improve our chances of sticking with them.
Luke explains why the pandemic triggered a surge in resolution-making, how the brain responds to fresh starts, and why January gym memberships soar even as long-term attendance collapses. He also shares evidence-based strategies that actually work, from setting specific and measurable goals to harnessing social support, using apps, and learning new skills that boost brain health as well as motivation.
This isn’t about willpower or guilt. It’s about understanding how humans change — slowly, imperfectly, and with the right conditions. If you’re setting intentions for the year ahead, this is the science you want on your side.
You can email Luke with questions or suggestions for future episodes at [email protected].

For his Christmas podcast, Professor Luke dives into one of the oldest, strangest and most delightful human behaviours: kissing. And yes, there really are scientists who study it. Kissologists? Why not. Someone has to keep the flame of enquiry burning under the mistletoe.
Kissing isn’t new. In fact, our primate ancestors may have been at it 21 million years ago. Humans, chimpanzees, bonobos and orangutans all kiss, and the trail of evolution suggests the ancient snog goes back to a shared forebear long before Christmas was invented.
So why do we do it? Luke’s answer brings joy to his immunologist’s heart: kissing is fundamentally about the immune system. It’s bonding, soothing, socially rewarding… but it’s also a biological exchange of information. When we kiss, we taste another person’s immune profile through their saliva. We’re wired to choose partners whose immune systems are similar enough to blend but different enough to give our potential offspring an advantage — the Goldilocks zone of mate selection.
Kissing is also bound up in how humans live. We’re pack animals; our wellbeing depends on social closeness. For parents, early kissing and mouth-to-mouth feeding once helped babies survive. For adults, it floods the brain with oxytocin — the same hormone released during breastfeeding — building trust, comfort and connection.
And yes, kissing is… messy. Saliva production surges to dissolve bacteria. Mouth microbes are swapped. Germs hitch a lift. Glandular fever is the classic “kissing disease,” especially among teenagers, and herpes simplex moves easily through saliva. The upside? Some research shows kissing can reduce allergic reactions — including a study where hives became less severe after a 30-minute smooch.
The benefits stack up: reduced stress, better bonding, endorphin release, raised heart rate, improved mood, and even potential perks for your complexion. A deep kiss works 24 facial muscles, stimulates circulation and boosts collagen. Science says the Christmas kiss might be good for your skin as well as your soul.

It’s that time of year when the big nights out collide with the biological reality of the morning after… and Professor Luke is here to explain exactly what’s going on in your head, your liver and your rattled nervous system.
Hangovers are ancient — literally. Chimps get tipsy on fermented fruit, so our ancestors were drinking alcohol millions of years before the first Christmas party. Humans began brewing around 10,000 years ago… and the first hangover probably arrived right on cue.
Luke breaks down why hangovers feel so grim: the acetaldehyde formed when alcohol is broken down in the liver; the dehydration caused by alcohol acting as a diuretic; and the rebound in neurotransmitters like glutamate that may fuel “the fear”, the “living horrors”, and that uneasy post-session anxiety listeners know too well.
He runs through the classic symptoms — headache, fatigue, nausea, tremors, dizziness, sweating, irritability and a heart that seems to have joined a drum circle — and explains why some drinks make it all worse. Darker alcohols carry extra chemicals like tannins and methanol that crank up the misery, while clearer spirits tend to be less punishing.
Luke also notes a surprising trend: alcohol consumption in Western countries has fallen by a third since 2001, while alcohol-free beer is booming. Even French vineyards are pulling up vines because people are drinking less wine. Maybe we’re finally copping on — and our livers are grateful.
And of course, we get to the good stuff: how to avoid a hangover, and how to treat one. Hydrate between drinks, rotate in 0.0% options, eat beforehand, skip the full Irish, take B-vitamins or clove-based remedies if they help you, steer clear of paracetamol, and leave “the hair of the dog” to folklore. Sugar helps, rest definitely helps, and moderation helps most of all.
Luke’s holiday message? Enjoy yourself — but pace yourself. Your future self will thank you when the sun rises on December 26th.