4th August 2017

Trials and tribulations continued in July with a significant knee injury. I've been having meniscus problems in my knee for the last seven months and now I'm waiting for a scan. It looks like it needs surgery so I'll be out of action for a while.

Today’s newsletter is all about how biology interacts with psychology. If you want to know what gets in the way of making good decisions then read on...

Reading time: 5 mins

Criminals and Naughty kids - who is to blame?

the Prefrontal Cortex and decision making

It’s easy to think that naughty kids and criminals are bad people who make bad choices. Most humans love to judge and criticise the behaviour of others. The more hideous the behaviour, the more our emotions get stirred.

You see, one of our tribal tendencies is the love of justice. For hundreds of thousands of years, we lived in small tribes. Back then it was critical that everyone contributed to the survival of the tribe. Any behaviour that would threaten the survival of the tribe, wouldn’t be tolerated.

Not so long ago, people like you and I were celebrating public hangings and stoning people to death. If you’re a Braveheart fan like me, think of William Wallace getting hung, drawn and quartered!

So we don't hang people anymore but the media thrive on our primal lust for justice and public shaming. But the question I want to begin with is this:

Is this an out of date way of thinking about criminals? Are they to blame or were they destined to commit the crime?

First a little caveat: 

I want conversations that embrace complexity. I don't want to simplify things so they become polarised. Villain or victim, good or bad, sinner or saint. If you don't condemn, you condone. If you try to understand, it's as if you're justifying. These conversations are everywhere in modern society. But they breed narrow-minded, judgemental and discriminatory thinking. Every criminal should pay for their crimes but I want to introduce a nuance to the conversation.

Allow me to introduce you to someone that has inspired me of late. His name is Robert Sapolsky and he is an American neuroendocrinologist and author. He is a professor of biology, and neurology at Stanford University. His insights into stress, developmental biology, primate behaviour and toxoplasmosis are mind blowing. After hearing him speak on a podcast called 'The Joe Rogan Experience' I was captivated. I watched his TED talks, listened to his lectures on YouTube and bought his books (links to follow).

What I want to introduce you to now, is a part of the brain called the prefrontal cortex. This region of the brain governs much of our behaviour. Let’s see what Wikipedia has to say about it:

This brain region controls the planning of complex cognitive behaviour, personality expression, decision making, and moderating social behaviour.


The prefrontal cortex controls executive function. This affects our ability to determine between:

  • good and bad
  • better and best
  • same and different
  • future consequences of current activities

The prefrontal cortex also helps us to work toward a defined goal and predict the outcomes of our actions. The big one for this story is that it influences “social control" AKA the ability to suppress urges. Failure to suppress urges leads to socially unacceptable outcomes.

The scientific consensus states that the prefrontal cortex might not fully develop until the age of 25. For some, they develop sooner and for some it will never fully develop.

The Marshmallow Test

In the past, I have spoken about The Marshmallow Experiment and its ability to predict success in life, whatever that means! Researchers placed one marshmallow in front of a child. They got told that if they could wait for 15 minutes they would get rewarded with a second marshmallow. Children able to delay gratification went off to achieve more successful lives. The impulsive children had less successful lives. 

Researchers went on to discover the regions of the brain involved in this task. The two regions were the prefrontal cortex and ventral striatum. They found higher levels of activity in the prefrontal cortex in participants who delayed immediate gratification in favour of a greater reward later on. Fascinating, right?


So what affects the development of the prefrontal cortex? 

According to Robert Sapolsky, there’s quite a lot:

  • How hungry you are:
    • Hypoglycemic states (low blood sugar) reduce prefrontal cortex function.
  • How tired you are:
    • Consistent lack of sleep reduces activity in the prefrontal cortex.
  • How much pain you’re in:
    • The more pain you suffer the lower the activity in the prefrontal cortex.
  • If you're a male, your testosterone levels:
    • The higher your testosterone levels the lower the activity in the prefrontal cortex.
  • How stressed you are:
    • Too much of the stress hormone, cortisol, makes the prefrontal cortex atrophy (shrink). 
  • How traumatised you’ve been in the last five months:
    • Psychological trauma and sustained stress atrophy (shrink) the prefrontal cortex.  
  • What versions of a number genes do you have:
    • Some genes will give you a less developed prefrontal cortex.
  • How much stress you were exposed to when you were a foetus:
    • The more stressed your mother was the less developed your prefrontal cortex will be.
  • How much lead you were exposed to:
    • Exposure to lead reduces the development of the prefrontal cortex
  • What your nutritional status was when you were a foetus:
    • Babies receiving less nutrition in the womb have a lesser developed prefrontal cortex.
  • If your ancestors had a culture of honour:
    • Some studies suggest that some cultures are more impulsive where honour gets involved.

As you see there are many environmental factors influencing our ability to control our behaviour. It's clear to me that some people cannot control their own behaviour. They do not have the same ability as others to pause and think:

  • “Is this a good idea?”
  • “What will happen if I steal that car?”
  • “Who will get affected if I burgle this house?”

There is a reason why the majority of criminals come from the poorest estates. There’s also a reason why some people achieve remarkable things in life. Our impulsive behaviour is inextricably linked to the development of our prefrontal cortex.

So we should think twice before we criticise people for committing crimes. Especially when we know so little about their upbringing and their prefrontal cortex. Because some people literally cannot control their behaviour!

If you enjoyed this developmental biology lesson you have to learn about toxoplasmosis. Parasites also have some scary influences on our behaviour! And Robert Sapolsky is your man...


Best of the Month

Best book

The title says it all! This book is a refreshing take on life, that I am thoroughly enjoying.

Best podcast 

If you've read either of my mammoth blogs on fat and cholesterol then you'll know I'm passionate the stuff. The STEM-Talk podcast has been invaluable in my own education. In this interview, Dr David Diamond talks about the real science of fat, cholesterol and Statins. This is a must.

If you missed either of my blogs on fat, please find the links below:

Best article

Get to the bottom of your food cravings and learn why it's so hard to cut carbs, with Steven Guyenet...

Best of YouTube

This was one of the best documentaries I've watched in a long time. A fascinating story full of mystery about the origins of Maori's in New Zealand. Well worth the watch especially if you love New Zealand as much as I do!

That's it for this month's newsletter.

Please feel free to pass this onto friends and loved ones.

All the best

James @