Is Love Biological Bribery? │ How Love Makes Us Human with Dr Anna Machin

How does nature reward you for cooperating with your fellow humans? Through a cocktail of chemicals that works not unlike some illegal substances. Welcome back to our new series on love.

Love is the solution evolution has come up with to make sure we partake in survival-essential cooperation. It does this by producing a cocktail of neurochemicals which motivate and reward us for starting and maintaining our relationships with lovers, family, friends and children.

Oxytocin is the first of these and it's really important at the start of a relationship. It works by lowering your inhibitions to starting relationships with new people. And it does this by quietening the fear centre of your brain, the amygdala. Which means that that nagging voice in the back of your head that saps your confidence is quietened. But oxytocin isn't released alone. Whenever oxytocin is released, dopamine comes with it.

Dopamine is your general body's reward chemicals, so you get it released whenever you do anything that you enjoy. So, it might be drinking a glass of red wine, eating chocolate or viewing pictures of puppies on Instagram. But the relationship with oxytocin and dopamine is really critical for the start of a relationship. First of all, they increase the plasticity of your brain and this means it's more open to change. And it does this in two key areas of the brain: your memory and your learning. So, it enables you to efficiently learn everything you can about this new person in your life and then encode it into your memory. The other thing oxytocin and dopamine do by being together is knock the edges off each other. Oxytocin is a wonderful chemical. It makes you feel euphoric and so relaxed. However, if you just had it on its own you might be so chilled that you actually don't make any effort to start the relationship. So, because dopamine is the hormone of vigour, it's wired into your motor circuits, dopamine acts to motivate you to go across the room and strike up a conversation. So, oxytocin and dopamine are key at the start of a relationship. They are joined by serotonin.

Now you might have heard of serotonin because it's implicated in some depressive disorders, but it's also implicated in obsessive compulsive disorder. And this might give us a hint as to why it's involved in love. When people fall in love, then we see a drop in serotonin, and this is also what's seen in people with obsessive compulsive disorder. So, we think serotonin has a role in the obsessive elements of love, the bit that makes you talk about your new lover all the time or show your friends endless pictures of your baby. It's a key part of love because we have to be slightly obsessed with the people, we're in love with, just so we make the effort to coordinate our lives with them or make sure we know how they're feeling. So, oxytocin, dopamine and serotonin are all really good for the start of the relationship. However, human relationships last for decades and oxytocin in particular is not powerful enough to underpin these relationships in the long-term. Partly because we build tolerance to it. So, we need something much, much more powerful, something that's going to underpin the relationship in the long-term, and that is beta-endorphin.

Beta-endorphin is your body's natural opiate. It's actually released when you are in pain. It's your body's natural painkiller. But over evolution it's been co-opted into our social areas of our brain, so it is what rewards you for actually being in relationships for the long-term. And it can do this because it is addictive like any other opiate. So, the way it works is that when we're with the person we love, we get a wonderful hit of beta-endorphin. It makes us feel euphoric. Those of you who go to the gym might recognise it as being the chemical behind the runner's high. But when we go away from the person we're in love with, we start to go into opiate withdrawal and that motivates us to go back to the person. And that basically is the mechanism that underpins love in the long-term. But beta-endorphin is wonderful because it's released by lots of different behaviours that we can all carry out. So, for example touch, laughter, singing, dancing, exercise all release beta-endorphin. And this means it can underpin human relationships from those between lovers and children and friends and family up to huge football crowds. So, if a long-term relationship is a bit like a drug addiction, what are the side effects?

More on that next time. Subscribe to stay tuned and hit the bell to get notified about new videos. Bye for now.