The genotype, brain structure and biochemistry of boys, is a compliment to the previous blog on the brains and hormones of girls.
At six weeks of gestation, the Y chromosome causes development of gonads, the testes in boys.
Intrauterine development continues with testosterone producing the reproductive tract and male characteristics of the brain and genitalia.
In early development, prior to age five – boys learn and grow by spatial versus sensory learning. Via right hemisphere dominance – boys fidget, move, jump, throw things, walk and explore further than girls.
Boys as infants learn to identify faces and voices later than girls.
Language development is different in boys – they generally use less words and their verbal center is typically only in the left hemisphere.
Boys use their body and movement for learning, communication and enjoyment.
Boys use more gray matter vs. white matter which gives them an ability to focus on tasks more than people.
By nine or ten, boys have less memory, a smaller hippocampus, and less emotional data.
Boys are more impulsive and distractible. They make their decisions with more independence, more speed and less analyzing.
Cortisol and testosterone morph stress reactions into fight responses, drug and alcohol abuse, and high-risk behavior in adolescent boys.
Later puberty than girls, period of brain growth and pruning of unused grey neural cells occurs without much hormonal influence, at ages ten through twelve. Less emotional changes, but similar self-esteem drops to females.
White and grey matter volume peaks at 14.5 for boys, four years later than girls.
Steeper rate of white matter (longitudinally arranged myelinated axons) growth in adolescence for males. Facilitated by exercise – causes cognitive growth, motor performance and complex linguistic abilities to thrive in older adults.
Smaller corpus callosum means less interaction between hemispheres and less ability to verbalize emotions.
Less active frontal lobes mean less verbal in speech and writing.
Less ability in reading emotions and seeing in dim light due to occipital lobe structure.
Less data in parietal lobe in males allows for higher pain tolerance and less need for long-term tactile contact. Lower intimacy imperative in males.
Males tend to hear less, catch less inflections and remember less due to weaker neural connections in temporal lobe.
Testosterone and thalamus structure cause more risk-taking behavior, physically aggression, competition and less emotional processing than females.
Later prefrontal cortex development results in moral and emotional maturation five years later than females.
Rather than polarizing what is uber male and what is uber female, maybe we can shift to another paradigm. Males and females appear to be on this continuum of brain structure, where males have some female aspects and females have some male aspects of brains/biochemistry influencing the degree of right brain or left brain integration. These traits effect boys and girls with various combinations of task/physical or emotional/relational orientation. Perhaps that framing of reality will allow us to appreciate and respect each other’s strengths and personhood and hopefully reduce the unhealthy competition when children become very aware of what it means to be a boy or girl in a community.
In closing, please remember the Lord Jesus Christ as He came – perfectly God and perfectly human – this Christmas Eve. A reflection of the male and female aspects of the Imago Dei spoken of in Genesis 1. May we become more like Him this coming year by the work of the Holy Spirit.
Gurian, M. (2002) the Wonder of Girls: Understanding the Hidden Nature of our Daughters, New
York, NY: Pocket Books
Institute of Medicine (US) Committee on Understanding the Biology of Sex and Gender Differences (2001). Wizemann TM, Pardue ML, editors. Washington (DC): National Academies Press (US).
Jantz, Gregory (2014). Brain differences between genders. In Psychology Today online. Retrieved from: https://www.psychologytoday.com/us/blog/hope-relationships/201402/brain-differences-between-genders
Kirk I. Erickson, Teresa Liu-Ambrose (2016) Exercise, Cognition and Health. In Handbook of the Psychology of Aging (Eighth Edition), sciencedirect online. Retrieved from:
Lenroot, R.K., Gogtay, N., Greenstein, D.K., Wells, E.M., Wallace G.L., Clasen, L.S., Blumenthal, J.D., Lerch, J., Zijdenbos, A.P., Evans, A.C., Thompson, P.M., & Giedda, J.D.. Sexual dimorphism of brain developmental trajectories during childhood and adolescence. In NeuroImage 36 (4) online. Retrieved from: https://www.sciencedirect.com/science/article/pii/S1053811907002340