Home Page

Young Girls and

Part I:
Understanding the
Island Syndrome

Part II:
Biology and

About Harley

The Island

Site Map

Harley Hahn
Home Page

Send a Message
to Harley

Free Newsletter


Part 2: A Link Between Biology and Technology

(September 15, 2010)

The Female and Male Brains

As you know, men and women tend to think differently in a variety of important ways. What you may not know is these differences are more than cultural: they are based on physical differences between the male and female brains due to the influence of sex hormones, especially on the developing nervous system. As you would imagine, the details are complex and not completely understood. Here, however, is a basic summary that is good enough for our purposes.

The human nervous system starts to develop early in the life of the fetus; as it develops, it is sensitive to the influence of sex hormones. By 6 weeks of age, the male fetus starts to produce male sex hormones called "androgens", the most important being testosterone. Without testosterone, the fetus naturally develops a female nervous system. With testosterone, the fetus develops into a male nervous system.[14] In relative terms, this early dose of testosterone is a large one. In fact, its effects are just as important as the later, more obvious surge of testosterone that begins at puberty.

At about 8 weeks of age, the fetus' nervous system begins to develop, at which time it is exquisitely sensitive to the presence or absence of male hormones. If there is no testosterone, the fetus will develop a female nervous system. Under the influence of testosterone, the fetus will develop a male nervous system.[15]

Anatomically, the differences are small, but they do become significant later in life. In fact, certain areas of the child and adult brain will be larger or smaller, depending on whether or not testosterone was present during the earliest stage of life. Specifically, the female brain will develop more neurons and more connections in the parts of the brain responsible for verbal skills, emotion, and processing gut feelings. In the male brain (under the influence of testosterone), these areas will be smaller and less developed. However, there will be significantly more growth in the areas of the brain responsible for sex and aggression.

The differentiation of male and female brains takes place in two main stages, both under the influence of sex hormones.

Throughout childhood, these anatomical differences do effect behavior. For example, girls tend to be more verbal than boys, and boys tend to be more competitive and aggressive than girls. It is during puberty, however, under the influences of sex hormones, that behavioral differences widen. Thus, the differentiation of male and female brains takes place in two main stages, both under the influence of sex hormones.

To start, at about the 8th week of development, the fetus' nervous system becomes either masculine or feminine. Later, during puberty, under the influence of more sex hormones, the job is completed.

We are now ready to take another look at the examples we discussed earlier, and start tying it all together. We'll begin with Reina, the Queen of Text Messaging.

Jump to top of page


A Link Between

The Island Syndrome
1. What Is the Island Syndrome?
2. What's in the News?
3. Difficult Questions
4. Why the Nature of Communication...
5. No Man Is an Island
6. Putting a Name to the Malaise
7. The Lady and the Psychiatrist
Living in the Bubble
8. What's in the News?
9. The Three Mandatory Machines
10. Life in the Bubble
11. Why We Keep On Keeping On
12. The Lady and the Psychiatrist
The Importance of the Brain's Biochemical Environment
13. What's in the News?
14. The Story of Dave
15. Importance of Neurotransmitters
16. The Stuff of Moods, Feelings and...
17. What Does Dave Need?
18. The Lady and the Psychiatrist
19. Introduction to Part II
20. The Island Syndrome
21. Excessive Text Messaging
22. Excessive Pornography Use
23. Understanding the Biology
24. Hormones and Neurotransmitters
25. The Pleasure Center
26. Too Much, Too Fast: Craving and...
27. The Female and Male Brains
28. Biology of Excessive Text Messaging
29. Biology of Excessive Pornography...
30. Conclusion: The Island Syndrome...
31. References