Bringing up girls: Biology and behaviour

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.

Generations of parents and teachers have often used expressions like ‘boys will be boys’ and ‘it’s just a girl thing’ to help describe or justify children’s behaviour.

For some people such phrases are overly simplistic, yet there is a vast body of scientific research suggesting that differences in how girls and boys behave and learn, may be part of the reason why. 

Given that we know so much more about child development and in particular the development of the human brain it seems timely to look at such differences with the insights provided by science.  The following article focuses on girls and explores some of the research and what this means in terms of raising girls.

The male and female brain

Prior to unpacking the biology of sex differences and how they relate to differences in behaviour and learning, it is important to note that there is a vast and growing body of research suggesting that fundamental differences between girls and boys can be explained through looking at the unique structural and chemical differences found within the brain of each sex. 

There is mounting evidence suggesting that the physiology of the female brain plays a tremendous role in how girls engage with the world around them, behave and learn. 

Since the mid 1990s we have learned a great deal about the human brain and importantly some of the most prominent reasons why girls may act and behave the way they do have been uncovered by neuroscientists. 

Indeed, studies looking into the inner workings of the brain suggest that while society and culture play a role in shaping behaviours, there is also much to say about the innate differences that exist between girls and boys. 

This is not to say that neuroscience has finally answered all questions related to nature versus nurture, but rather it has recognised important sex differences in the brain which influence how girls behave with the world around them.  This is evident in the very early days of life.

Social skills and oral language

One of the most significant differences between females and males and well documented is that females have superior social skills. Females show greater eye contact than males, demonstrate superior social understanding and sensitivity to emotional expressions and even show better understanding of social themes in stories. 

The extent to which such superiority is the result of nature or nurture is not completely clear but there does appear to be a biological origin which is evident in infants.

In a ground-breaking study conducted in the United Kingdom, researchers found differences in how one day old girls and boys engaged with their surroundings. 

Quite simply, and prior to any substantive environmental influences, one day old girls were more interested in looking at faces while their male counterparts focused on, and took greater pleasure in, the objects around them. 

This difference was evident across many children with various cultural backgrounds and the researchers concluded that given the children were only a day old, such differences could not be explained by experience. In other words, these differences could only have resulted from innate biological differences. Such biological tendencies are supported by other neuro-scientific evidence and the experiences of those adults who are immersed in the day-to-day interactions of children.

Another prominent difference evident in young children is that girls generally develop the capacity to communicate earlier than boys. 

On average, girls are about eighteen months ahead of boys in terms of oral language and vocabulary development and boys do not seem to catch up until six or seven years of age. 

It is noteworthy that Finland, a country that regularly ranks one of the highest in terms of literacy and numeracy, does not enrol children in school until seven years of age. 

There are a number of reasons for this approach but one of those is founded on a concerted effort to ensure that ‘sex’ differences, as they pertain to communication skills, do not disadvantage boys.  Girls will talk more and with greater fluency early in life and such differences are also due to the fact that the rates of maturation of the brain’s hemispheres are different between girls and boys. 

Multiple studies have shown that the female brain appears to be coded to grow more quickly across the hemispheres with regions of the left hemisphere developing faster in females than in males. The left hemisphere of the brain will also grow to be slightly larger than the right in females while the right side of the male brain will become larger than the left. The significance of this lies in what neuroscientists refer to as the ‘lateralisation’ of brain function or, simply stated, what task each of the hemispheres may be responsible for. 

For example, it is now widely recognised that the left hemisphere is the primary region for comprehending and processing language, and in early infancy girls show left hemisphere dominance for speech perception. Moreover, as they mature, girls begin to use both hemispheres for most language activities. Early dominance in this area means that girls generally speak sooner and with greater proficiency than boys. 

Aside from how language appears to be lateralised between the hemispheres there are also some structural differences that impact on the processing of language as well as other important functions.

One of these structures is a band of tissue that connects the right and left hemispheres and is known as the corpus callosum.  The corpus callosum acts as a bridge between the thinking areas of each hemisphere and allows for the flow of information from one hemisphere to the other. Numerous studies have identified that the corpus callosum of females maintains greater neural density and is thicker and more bulbous than its male counterpart.  In simple terms this means that females have a greater number of connections between the hemispheres and consequently greater efficiency and cross talk between each hemisphere.

The importance of relative size and neural density in the corpus callosum as it relates to particular behaviours and attributes generally depends on particular cognitive functions.  In terms of fluency and articulateness in language, the degree of connectivity in relation to the number of neural connections between the hemispheres has been shown to be of great significance. 

Moreover, studies beyond those focusing on the brain tell us that females, as compared to males, typically have higher verbal IQs, greater proficiency in a range of language related tasks and abilities as well as superior verbal fluency.  In practical terms what all of this means is that girls talk more and with greater fluency than boys and this capacity is intimately linked to a girl’s emotional skill set.

Emotional awareness and the ‘intimacy imperative’

A further early sex difference is related to emotional awareness, and can be found in a young girl’s sensitivity to facial expressions. This sensitivity has been linked by a number of neuroscientists to lower levels of testosterone in females. 

Neuroscientists believe that because the female brain is not immersed in high levels of testosterone in the womb a girl arrives in the world better at reading faces, hearing human vocal tones and empathising with others.  

Moreover, studies have found that infants and toddlers with lower foetal testosterone demonstrate higher levels of eye contact, better communication skills and larger vocabularies.  And while some boys do arrive with those types of skills, it is generally girls who are born with the innate abilities for immediately connecting with the people around them. 

A girl’s need for connecting with others could be described as an ‘intimacy imperative’.  Indeed, the evidence suggests that connecting with others is perhaps one of the most important aspects of a girl’s emotional well-being. Girls appear programmed to engage in social harmony and intuitively know how to use this in both positive and negative ways; generally speaking, this is true of females of all ages.

For example, there is an abundance of research demonstrating that female aggression is most often seen through damaging relationships.  For females, social exclusion, reputation damage and ignoring individuals replaces physical violence and can be more damaging long term.  In other words, when girls want to hurt someone they do so by disrupting any measure of social harmony or engaging in what some researchers have coined as ‘relational aggression’.  It is worth noting that relational aggression has been observed in over one hundred different societies, suggesting something more than culture may be at work in terms of this type of behaviour.

The importance of relationships for girls cannot be understated.  Arguably relationships are important in the lives of all children, however it should come as no surprise that during the early days of toddlerhood and childhood, boys and girls seek out, and engage in relationships very differently. 

Anyone who has ever raised, lived or worked with small children has witnessed examples of such differences.  From even the earliest days boys are more likely to be aggressive, competitive, boisterous and prefer toys that make noise and can be manipulated (a diplomatic way of saying pulled apart or destroyed).  Girls on the other hand are much more sociable, passive, talkative and show greater capacities for listening, concentrating and paying attention. 

What does this mean for raising girls?

So, what does this mean for parents of daughters, caregivers and teachers of young girls?  First, it means that we should accept that boys and girls will engage with the world differently and have different priorities in terms of play, learning and relationships. Second, while relationships are important and both boys and girls require social interaction for all aspects of development, positive relationships are that much more important for a girl’s overall sense of self and well-being.

It is, therefore, imperative that the innate needs of girls are nurtured by adults through fostering positive relationships and monitoring when relationships go wrong between girls, their friends, siblings and/or any significant adults.  

And finally, girls are good at, and love to communicate which means that adults need to be empathetic and enthusiastic listeners. As a father of a daughter, and in spite of the work I do, I learned the hard way that sometimes all that my daughter wanted was a sympathetic ear to hear her thoughts and a shoulder to comfort her when needed. 

In the end, girls and boys will behave and engage with the world differently and as such it is important to recognise that much of this is innate and as such should be nurtured in a way that meets the needs of the young girls in our lives.