Class15_Sex+differences+in+behavior2

Class15_Sex+differences+in+behavior2 - Sex Differences in...

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1 Sex Differences in Behavior Sex Differences in Behavior • Development of behavior is influenced by both genetic and environmental factors • The goal today is not to establish that behaviors are hormonally/genetically regulated or learned (both factors are important!) Outline • Play behavior – Effects of testosterone in monkeys – Congenital adrenal hyperplasia • Sex differences in the brain – Rats and humans – Mating systems • Effects of hormones on brain development • Effects of genetics on brain development Play Behavior • Captive vervet monkey were given human toys to play with • No prior exposure, presumably could not learn from parents Hot Wheels • When given a choice between toys with wheels and plush toys, male vervet monkeys and boys preferred wheeled toys • Female vervet monkeys and girls played with both toys Rough and Tumble Play
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2 Rough and Tumble Play in Humans • Boys and girls engage in rough and tumble play • Boys are more likely to spend more time in rough and tumble play What is the Cause of Sex Differences? • Parents can influence how their children play • Are genes or other biological factors involved? – Keep in mind, the environment can affect hormones and gene expression What Causes These Differences? • Pregnant female rhesus monkeys were given testosterone • Female offspring developed as pseudohermaphrodites (external genetalia was masculinized) • Researchers studied play behavior Organization of Behavior • Play behavior of pseudohermaphrodites was more like males than females (note, not an exact match) • Indicates that testosterone acts during development to organize the brain to function more male-like 0 5 10 15 20 25 30 Rough and tumble play (frequency) Males PseudoH Female Congenital Adrenal Hyperplasia • A disorder in which the adrenal gland produces androgens instead of cortisol (androgens are a precursor to cortisol) • Girls are born with ambiguous genitalia. Treatment with dexamethasone (a form of cortisol) and reconstructive surgery • Early treatment usually results in normal lives Behavioral Changes • Surveys reported that girls treated for CAH were more likely to : – Prefer male playmates – Be characterized as “tomboys” – Display reduced interest in infant care – Prefer “male-typical” toys • Hard to assess impact of environmental factors, since child and parents know about the early hormonal abnormality
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3 Behavioral Observations • A subsequent study secretly observed play sessions of girls with CAH and unaffected sisters • Girls with CAH showed masculinized of some aspects of play behavior (but not rough and tumble play) 0 20 40 60 80 100 Percentage male Boy CAH Boy Con Girl CAH Girl Con
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Class15_Sex+differences+in+behavior2 - Sex Differences in...

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