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Why boys wrestle, play fight and fidget

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Father and sons skateboarding


Whether you have a boy or a girl you may have wondered what science can tell you about the role of the brain in shaping your child's behaviour. In this two-part series author, speaker and academic Dr Michael Nagel, explores gender differences from a neurological perspective and opens the door to a greater appreciation for how we parent, educate, and support our children.

“Stop fidgeting!”, “Sit still!”.  How many times have you heard someone say either of these things to a young boy? And how many times have you seen boys unable to follow such requests?

Science tells us that because of their biological makeup, sitting still is just not an easy proposition for boys. 

Most boys regularly appear to be in a state of perpetual motion and some much more so than others. Even when they are looking at books or reading you can see boys tapping their feet or fidgeting in some fashion. 

Importantly, this is not necessarily some type of behavioural problem but is actually a biological imperative given some of the chemicals swirling around in the bodies and brains of boys.

In fact, research into the development of the male and female brain suggests that brain development during pregnancy goes a long way towards shaping these types of behaviours.  

From the beginning it is important to consider that all children start off anatomically identical and this includes the brain of every child.

It is the introduction of additional male hormones triggered by a boy’s Y chromosome during first trimester that is not only responsible for the development of the sexual organs and other physical differences but also for creating a ‘male’ brain.

These changes suggest that the reason why boys generally act differently to girls is at least partially due to the brain’s biological makeup. 

Parents and educators alike witness some of these differences every day. 

A shorter attention span and being more adept at learning spatially, along with needing more rest and being in a seemingly constant state of motion are just some of the ways adults can see how boys differ from girls.

There are multiple factors that contribute to these differences and to the endless energy and movement of a boy that are beyond the scope of this article. However, there are two important chemicals that help us to understand why movement is not only more pronounced in boys than in girls, but is also so very important for their overall development. These two biological elixirs include testosterone and serotonin.

Prior to looking at how testosterone and serotonin impact on the behaviour of boys it is noteworthy that movement and physical activity are, in themselves, incredibly important to both boys and girls.

Given how technology has become so pervasive in our lives, the important links between movement, physical activity and healthy development cannot be stressed enough. All children need to move, and movement is integral to all aspects of development, and this is especially true when testosterone is meandering through the minds and bodies of boys.

Playful aggression is hardwired into males and not just in our species but in most primates. Moreover, testosterone also appears to be a major contributor to the constant movement and energy levels of boys and as such is not something that can easily be switched off simply by command. This is also exacerbated by another chemical called serotonin.
Dr Michael Nagel

The role of testosterone

Most people are aware that testosterone is the primary male sex hormone and is associated with a range of behaviours including mating and aggression. 

Some studies have even linked testosterone with various levels of anti-social behaviour, criminality, and gambling. 

In terms of boyhood, it is important to note that there have been many studies linking testosterone to inattentiveness, impulsivity, physicality and movement. 

Testosterone not only fosters male physical characteristics but also aggressive and competitive behaviours, territoriality, and later in life, sex drive. 

Testosterone is the reason why boys find things more interesting than people and why they engage in exploratory and rough and tumble play. 

As boys grow into men, high levels of testosterone tend to make males more aggressive and/or ambitious, have larger muscles, and be more dominating. And while it is true that females do have testosterone, it is not the prominent sex hormone in girls. 

For females, progesterone and estrogen are the dominant hormones which in turn foster female physical growth and promote bonding and attachment behaviours and incline girls towards cooperation over competition. 

Testosterone can also act much more differently in boys than in girls. For example, there is a substantive body of research telling us that testosterone and a boy’s amygdala operates somewhat differently than that of a girl.

The amygdala is a structure deep in the emotional part of the brain that helps to weigh up danger and elicit a fear response along with numerous other behaviours.

In males the amygdala is not only larger than in females but is also rich in testosterone. In simpler terms this means that the interplay of increased levels of testosterone in a larger amygdala is one of the reasons why young boys are far more inclined to engage in playfully aggressive, or rough and tumble, behaviours.

Playful aggression is hardwired into males and not just in our species but in most primates. Moreover, testosterone also appears to be a major contributor to the constant movement and energy levels of boys and as such is not something that can easily be switched off simply by command. This is also exacerbated by another chemical called serotonin.

How serotonin impacts behaviour

Serotonin is a neurotransmitter. Neurotransmitters are chemicals secreted at the synapses of a neuron that allow neurons to ‘talk’ to one another. The communication which results from an electro-chemical impulse between neurons and neurotransmitters influences all aspects of our behaviour. Serotonin is one such type of neurotransmitter and is linked primarily with processing emotions and acting as a calming mechanism.  

Serotonin also plays a role in the control of eating, sleep and arousal, as well as the regulation of pain and various moods. Researchers associate high levels of serotonin with high self-esteem and social status while low levels of serotonin have even been linked to depression, impulsivity, risky behaviour, aggression, anger, and hostility. 

When serotonin levels are normal or elevated we feel good, when they are low we feel awful. People suffering from chronically low levels of serotonin are often clinically depressed and given medication to enhance the uptake of this feel good chemical in the brain. Significantly, and not unlike so many other chemicals in the brain, serotonin operates and fluctuates differently in males and females.

For those who raise and work with children, it is important to remember that both boys and girls have serotonin, however, for boys their level of this important chemical is often impacted by testosterone and other chemicals.  

Serotonin is also not processed as well in the brains of boys. In practical terms this often results in boys having lower levels of serotonin from time to time resulting in a greater predisposition to fidget and act impulsively. Therefore, asking a fidgeting boy to stop squirming or to sit still might be as successful as asking that same boy to hiccup on demand; when the uptake of serotonin in the brain is low, then fidgeting is often a common occurrence. 

As parents or educators, it might be sensible for us to adjust our expectations rather than trying to force boys to do something that is physiologically difficult for them. One way of doing this is to allow boys opportunities to move around and engage in physical activity when they appear restless or ‘fidgety’. 

That’s the paradox… promoting physical activity, especially high to low intensity activity, helps to calm the restless boy by altering their biochemistry. This isn’t about tiring a boy out, but rather about providing opportunities for him to balance out the chemical milieu of his mind. Moreover, taking a restless boy and putting him in a situation where he is expected to sit still for long periods of time or play quietly on demand is not always going to end well for anyone.

Top tips for parents

So, let’s wrap things up! You do not have to be an expert in neuroscience to know that boys tend to be in perpetual motion. Given the chance, they run, chase, dig, climb, build and destroy. 

It is rare to find young boys sitting quietly and listening and they seem naturally wired for movement. 

Testosterone and serotonin play a significant part in this behaviour and physical activity and play help mediate the impact of these chemicals. 

It is also noteworthy to emphasise that sedentary behaviour is not part of any child’s natural makeup.

Professor Japp Panksepp1, one of the world’s leading authorities on human and animal behaviour, believes that all children learn to control themselves and regulate their emotions better through play.

Therefore, in order to promote healthy social and emotional development it seems self-evident that rather than simply trying to curtail or stop a boy’s need to move, an alternative would be to provide him with plenty of opportunities to counteract the effects of testosterone and serotonin by allowing for plenty of activities where he can use up some of the seemingly boundless source of energy. 

In other words, appreciate that boys are built for activity. If he can’t sit still then give him opportunities to move in a way that harnesses and utilises that seemingly restless energy!  

And finally, it is significant to note that boys bond by doing things with other boys and with the adults around them as well, so foster opportunities to do so through playful activities. 

Boys, by their nature, are designed to be active, to throw things, to compete, to learn by doing and to explore the world around them even when the world, or at least the adults in it, would like them to slow down. And most importantly, if he can’t sit still, why try to make him? Instead, and rather than trying to correct a boy’s innate desire to move, accept his high activity levels and provide him with safe and developmentally appropriate opportunities to engage with the world in a physical manner whenever possible.


With a degree of understanding of, and compassion for, a boy’s biology this can be achieved by:

  • Appreciating, rather than bemoaning, the fact that boys are built for movement and activity. To that end, create opportunities, with the appropriate boundaries, for such activity. Provide boys with plenty of opportunities to move, and make physical activity a part of a task as much as possible.
  • Providing ‘brain breaks’ when necessary. If you are trying to have boys engage in some form of quiet activity and they are fidgety, wriggling around or annoying others then that is your cue to get them, and the other children, moving. As alluded to earlier, high intensity to low intensity activities help to calm the restless mind.
  • Not relying on screens as a babysitter… boys, and girls for that matter, do better when they are engaging with people instead of devices.
  • Providing boys with stress/squeeze balls or other handheld items that boys can manipulate during desired listening or quiet times. It turns out that when boys’ hands are active in this way it helps to calm them and limit fidgety behaviour.
  • Alternating quiet and physical activities and putting boys to work with jobs that require movement when you can.


1 Panksepp, J and Biven, L (20012). The Archaeology of Mind: Neuroevolutionary Origins of Human Emotions. New York:  W.W. Norton & Company.