Essay by akk713College, Undergraduate January 2004

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Hormones & Puberty

*Hypothalamus stimulates pituitary gland

-growth hormone "^ which causes growth spurt

-ovaries and testes release gonadotrophins (sex hormones)

*males: testosterone

*females: estrogen and progesterone

*hormones stimulate

-growth of primary sexual characteristics (genital)

-growth of secondary sexual characteristics (non-genital)

-precursors to adult sexuality

Sex Differences in Puberty

*Growth spurt begins

-10.5 years in girls

-12.5 years in boys

-girls taller than boys between ages 11-13 years

*full adult height

-17 years old in girls

-21 years old in boys

*Menarche: first menstrual cycle

-typically occurs by age 12-13

-initially may involve anovulatory, irregular cycles

*Spermarche: first ejaculation

-typically occurs by age 15

-initial period of sterility

*Puberty marks an increased incidence of internalizing disorders in girls compared to boys (Haward & Sanborn, 2002; Kessler, 2003)

*Due to hormones? Environmental variables? Pregnancy?

*Is depression adaptive? (Nesse, 2000)

Precocious and Delayed Puberty

*Girls who enter puberty early more likely to have teen pregnancy

*girls who have teen pregnancy, more likely to have daughters with teen pregnancy

*Vandenbergh Effect

-male present --> earlier onset of puberty

-females only --> later onset of puberty

-may be a way of regulating population density

*Stable species - unchanging predictable environments, live long lives in large populations, large bodied, lavish lots of parental attention on few offspring - reach puberty later

*Opportunistic species - unstable unpredictable ecosystems - conditions good, everyone begins mating or pollinating --> conditions favorable, reach puberty rapidly

*Absent Father Theory:

-girls abandoned by their father behave like females from opportunistic species and reach puberty earlier (Draper, Belsky, & Harpending).

-process may be caused by pheromones

*Strategies for reproductive success

1) early pubertal development, low investment in offspring

2) later pubertal development, high investment in offspring

(Belsky, Steinberg & Draper, 1991)

*Evidence in support:

-females with absent...