Evolution of the Male & Female Brain
Sexual Function & Arousal, Orgasm, Hormones, Hypothalamus, Pituitary Gland, The Limbic System, Left Right / Emotion Reason

Evolution of the Brain: Sex & Survival

3.4 billion years ago - Life appears. According to the fossil record, relatively complicated organisms like bacteria already existed when the earth was only one billion years old.

450 million years ago - the first Fishes. They posessed a very small brain, the first one that had existed on the earth up to that time.

300 million years ago - the first Reptiles. The brains of our reptile forebears were divided into three compartments: a front compartment for smell, a middle compartment for vision, and a rear compartment for balance and coordination. The basic instincts of survival - sexual desire, the search for food and the aggression responses of 'fight-or-flight' - were wired into the the diencephalon (a region between the smell brain and vision brain).

200 million years ago - the first Mammals
When the mammals evolved out of the reptiles, their brains began to change. First they developed a new package of instincts, related to the reptilian instincts for sex and procreation, but modified for the special needs of a mammalian lifestyle. Chief among these was the instincts for parental care of the young.

120 thousand years ago - Homo Sapiens appears. The growth of the cerebral cortex reached explosive proportions in the last million years of human history, culminating in the appearance of Homo Sapiens.
The primitive region in the brain, that held the circuits for the instinctive behavior of the reptile and the old mammal, was now completely enveloped by and buried within the human cerebral cortex. Yet this ancient command post is still active within us; it still vies with the cerebral cortex for control of the body, pitting the inherited programs of the old brain against the flexible responses of the new one.

Evolution of the Human Brain: Sex and Survival
http://primatesociety.com/Into/survival/timeline/textEvol.html - From the book: 'The Enchanted Loom, Mind in the Universe' by Robert Jastrow

The Hypothalamus

The hypothalamus is an exceedingly ancient structure and unlike most other brain regions it has maintained a striking similarity in structure throughout phylogeny and apparently over the course of evolution.
The hypothalamus is fully functional at birth and is highly involved in all aspects of endocrine, hormonal, visceral and autonomic functions and mediates or exerts controlling influences on eating, drinking, the experience of pleasure, rage, and aversion. The hypothalamus is the central core from which all emotions derive their motive force. The hypothalamus is also sexually differentiated. That is, structurally and functionally the hypothalamus of men and women are sexually dissimilar.

The Hypothalamus: Differences in Men and Women
http://brainmind.com/LimbicPrimer.html - 'The Limbic System. Foundations of Social, Sexual, Emotional Behavior, Love & Memory.' (Rnawn Joseph, Ph.D. The Brain Research Laboratory)

Nature vs Nurture: Male and Female Brains

In recent years, neuroscientists have found that male and female brains are wired differently because of the role of testosterone and other male hormones during gestation. Brains growing under the influence of male hormones are slightly larger and have denser concentrations of neurons in some regions.

Male brains also contain a greater proportion of gray matter, the part of the brain responsible for computation, while women have relatively more white matter, which specializes in making connections between brain cells

Average IQ is the same among men and women.

Intelligence tests have found that men, on average, perform better on spatial tasks that require mentally manipulating objects. Men also do better on tests of mathematical reasoning. Women tend to do better on tasks requiring verbal memory and distinguishing whether objects are similar. The relative strengths tend to even out, studies indicate.

If men do have a slight advantage in math ability, is the difference really biological, or are exceptional girls and women intimidated by cultural stereotypes and discouraged from cultivating their talents from an early age?

The Boston Globe. Matt Crenson, Associated Press. February 28, 2005

Nature vs Nurture: Male and Female Brains. Biology, Hormones, Culture
http://www.boston.com/news/nation/articles/2005/02/28/nature_vs_nurture_divides_academia/

Differences Between Male and Female Brains

From the essay: "Scientists working at Johns Hopkins University, reporting in the 'Cerebral Cortex' scholarly journal, have discovered that there is a brain region in the cortex, called inferior-parietal lobule (IPL) which is significantly larger in men than in women. This area is bilateral and is located just above the level of the ears (parietal cortex).

Furthermore, the left side IPL is larger in men than the right side. In women, this asymmetry is reversed, although the difference between left and right sides is not so large as in men. This is the same area which was shown to be larger in the brain of Albert Einstein, as well as in other physicists and mathematicians. After allowing for the natural differences in overall brain volume which exist between the brains of men and women, there was still a difference of 5% between the IPL volumes (human male brains are, on average, approximately 10 % larger than female, but this is because of men's larger body size).

Another study by the same group has shown that two areas in the frontal and temporal lobes related to language (the areas of Broca and Wernicke, named after their discoverers) were significantly larger in women, thus providing a biological reason for women's notorious superiority in language-associated thoughts. Using magnetic resonance imaging, the scientists measured women had 23% (in Broca's area) and 13% (in Wernicke's area) more volume than men."

Differences Between Male and Female Brains
http://www.cerebromente.org.br/n11/mente/eisntein/cerebro-homens.html

Prefrontal Cortex Controls Sex Urges, Sexual Arousal in Primitive Brain Area (Limbic System)

As most teenage boys know, it's not easy to keep hormones in check. While humans can control their level of sexual excitation with some effort, a new study suggests that this skill is a fairly recent gift from evolution.
By studying men watching pornographic videos, researchers in Canada have pinpointed areas of the brain that become active when the men tried to avoid being stimulated. In evolutionary terms, these regions of restraint are newer than the more primitive areas where the sexual urges arise in the first place.
Only primates have prefrontal cortexes. That region of the brain, located right behind the forehead, is most advanced in humans and is involved in analytical thinking, multitasking and problem solving.
The men's prefrontal cortexes turned on when they tried to control themselves. By contrast, erotic feelings prompted activity in older parts of the brain, including the region known as the limbic system, and the neocortex, which allows people to be aware of their feelings.

Prefrontal Cortex Controls Sex Urges, Sexual Arousal based in Primitive Brain Area (The Limbic System)
http://www.edwardtbabinski.us/male_brain/ - By Randy Dotinga November 29, 2006.

Arousal in Women, Viagra & Erotica: 'All in the Mind'

Scientists have concluded that women achieve most sexual satisfaction through the stimulation of their brain and not any other organ. After eight years of tests involving 3,000 women, Pfizer, the company behind Viagra, the little blue pill that has transformed men's sex lives, has abandoned efforts to prove that the drug works for females too.
Studies found that even though Viagra induced a greater pelvic blood flow in women. they did not feel substantially more aroused.

Read More: Female Sexual Stimulation, Viagra & Erotica: 'It's All in the Mind'

Report on Pornography, Right and Left Sides of Brain

The visual image is processed by the right side of the brain; print by the left. The latter is rational and analytical; the former holistic and pattern-recognising. Left brain/right brain research is beyond the scope of analysis of this paper, but clearly questions need to be asked about the impact of the visual (whether photographic or film) image on the brain, particularly the male brain, which recent research indicates has much less connection between its left and right halves than the female brain, and therefore possibly much less opportunity for the rational left to control the impulses generated by the impressionistic right.

'Sexual Offenders and Pornography: A Causal Connection?' by Marlene Goldsmith, Chairman, Legislative Council Standing Committee on Social Issues, Parliament of New South Wales

Report on Pornography: Right and Left Sides of Brain
http://www.aic.gov.au/publications/proceedings/20/goldsmith.pdf

Evolution of Brain: Erotic Images Prove Useful In Coaxing Out Unconscious Brain Activity

When your eyes are presented with erotic images in a way that keeps you from becoming aware of them, your brain can still detect and respond to the images according to your gender and sexual orientation, a team of University of Minnesota psychologists has found.

The purpose of the work was to uncover mechanisms by which the brain processes visual information that is not consciously perceived by the subjects. The researchers chose to generate brain activity by using erotic pictures because they promised to elicit strong responses and clear patterns in the data. But the researchers believe the mechanisms by which the brain processes such images are universal.
'This definitely doesn't just work for erotic pictures,' said psychology professor Sheng He, 'But erotic images stand out in terms of potency to generate a response.'

Evolution of Brain: Erotic Images Prove Useful In Coaxing Out Unconscious Brain Activity
http://www.sciencedaily.com/releases/2006/10/061026185636.htm - University of Minnesota

Erotic Images Elicit Strong Response from both Male and Female Brains

A new study suggests the brain is quickly turned on and 'tuned in' when a person views erotic images. Researchers at Washington University School of Medicine in St. Louis measured brainwave activity of 264 women as they viewed a series of 55 color slides that contained various scenes.

When study volunteers viewed erotic pictures, their brains produced electrical responses that were stronger than those elicited by other material that was viewed, no matter how pleasant or disturbing the other material may have been. This difference in brainwave response emerged very quickly, suggesting that different neural circuits may be involved in the processing of erotic images.

A great deal of past research has suggested that men are more visual creatures than women and get more aroused by erotic images than women.
'Usually men subjectively rate erotic material much higher than women,' says Andrey P. Anokhin (Ph.D., Research Assistant Professor of Psychiatry). 'So based on those data we would expect lower responses in women, but that was not the case. Women have responses as strong as those seen in men.'

Erotic Images Elicit Strong Response from both Male and Female Brains
http://www.sciencedaily.com/releases/2006/06/060614000616.htm - Washington University School of Medicine

Male, Female: The Evolution of Human Sex Differences

This book by David C. Geary attempts to explain human sex differences from a single theoretical perspective, Darwin's principles of sexual selection.
Rather than study gender roles (cultural constructions), which is the norm of many social scientists, Geary explores evolutionary biology.

Read More: Male, Female: The Evolution of Human Sex Differences

This Page Title: 'Evolutionary Philosophy of Mind: Male Female Brain, Sex Difference, Left Right Emotion Reason, Mental Health, Drugs'.
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Analyse any human emotion, no matter how far it may be removed from the sphere of sex, and you are sure to discover somewhere the primal impulse, to which life owes its perpetuation. ... The primitive stages can always be re-established; the primitive mind is, in the fullest meaning of the word, imperishable. ... Mans most disagreeable habits and idiosyncrasies, his deceit, his cowardice, his lack of reverence, are engendered by his incomplete adjustment to a complicated civilisation. It is the result of the conflict between our instincts and our culture. (Sigmund Freud)

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