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Evolution/Evolution of sex difference

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Question
Ok I am familiar with sexual dimorphism and sexual selection but how does that apply to humans? I have been curious because people say that society dictates how men and women are different. But are there really biological reason for men and women to behave differently? If so how do we seperate society from the science of behavior differences in the sexes?

Answer
Dear Adam,

The question of how much of human behavior is "nature" (genes) and how much is "nurture" (environmental influence) is an ongoing one, especially because one cannot ethically subject humans to controlled experiments to dissect out how much each component influences an individual's development.  But yes, there are absolutely biological differences between the male and female brain, much of it determined by the influence of sex hormones in utero.

Females, for example, generally have a larger corpus callosum, which is believed to facilitate greater communication between the two hemispheres of the brain in females.  Females also tend to have a larger limbic system.  But there is overlap between the sexes in all the various ways the brains *tend* to differ.  So while there are traits that are more commonly found in males or females, there's not really such a thing as a "male brain" or a "female brain."

You can read some nice overviews here:

http://www.webmd.com/brain/features/how-male-female-brains-differ#1

http://blogs.scientificamerican.com/talking-back/is-the-brain-gendereda-q-a-with

The best researchers can do on humans is post hoc examination of differences, which makes it nearly impossible to know for certain how much is due to genes, and how much to environment.  But with advances in molecular techniques, we may be better able to understand this in the future.

Dana

Evolution

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Dana Krempels

Expertise

I can answer questions about evolutionary mechanisms and theory, including genetic drift, mutation, natural selection, etc. I also can clear up misconceptions about evolution as it's sometimes talked about by those not well-versed in the subject (e.g., some politicians and many religious fundamentalists).

Experience

I have a Ph.D. in Biology, and presently teach Evolution and Biodiversity, Genetics, Botany, and Zoology at the University of Miami.

Organizations
House Rabbit Society Beta Beta Beta Biological Honor Society

Publications
Exotic DVM Magazine (veterinary journal)

Education/Credentials
B.S. in Biology B.A. in English Ph.D. in Biology

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