INTRODUCTION: WHAT MAKES A MAN

What Makes a Man : Certain brain areas and functions are built differently in the male and female brains and have evolved over time to produce the most successful versions of men and women. For example, the brain circuits that alert us to danger (the amygdala) and help us remember it (the hippocampus) are the sources of sex and individual differences in emotional memory. In Hamann 2005, the authors found sex differences in the amygdala response during emotion-related activities, such as formation of emotional memory and sexual behaviors. And for more on the evolution of male and female brain circuits, see Lindenfors 2007 and Dunbar 2007: they say "... there are striking differences between the two sexes in the social mechanisms and brain units involved. Female sociality (which is more affiliative) is related most closely to neocortex volume, but male sociality (which is more competitive and combative) is more closely related to subcortical units (notably those associated with emotional responses). Thus brain units have responded to different different selection

pressures." For more on cellular and genetic differences in the male and female brain, see Reinius 2008 and Arnold 2009b.

and the fix-it-fast emotional brain : Coates 2009 found that testosterone sets the male brain up for faster visuomotor scanning, faster physical reflexes, and more risky behavior.

Male and female brains : Penaloza 2009. The authors say, "Sex of the cell dictates its response." Malorni 2007 even found reduction-oxidation differences between male and female cells.

for later amplification by hormones : For more on sex hormones, genes, and the brain, see Arnold 2009c and Neufang 2009.

differences between women and men : For good reviews on sex differences in the brain, see Becker 2008b, McCarthy 2009, and Proverbio 2009.

role in shaping and reshaping our brains : It is important to note that biological predispositions can be shifted over time through experience and that existing dispositions can be mitigated or even overridden by situational demands in both men and women. For both males and females, upbringing, experience, and the environment can make long-lasting biological and behavioral impacts via epigenetic changes to our DNA. See Merzenich 1983 for early work on brain reorganization in response to changed circumstances. For more on changes in brain architecture with experience, see Kozorovitskiy 2005, and on environmental experience and epigenetic effects, see Meaney 2005, McCarthy 2009, and Murray 2009.