A. Why study hormones and effects on behavior (and vice versa)?
1. Important for fitness: Survival, Repr. Success
2. In animals learn about humans
3. Business applications: anabolic steroids, hormone replacement therapies,
endocrine disruptors (humans pol
ACTIVATIONAL effects on sexual behavior. Focus on chemosensory cues, olfaction,
role in hormone-mediated sexual behavior.
How do we know hormones activate sexual behavior?
o In women? hard to sort out effects of menstrual cycle (ovarian hormones)
NBL9 Sexual differentiation of behavior and brains in non-mammalian verts.
Avian sexual differentiation:
o Japanese quail, zebrafinch both very diff species, so any diffs may be general to
all birds. Japanese quail is a chicken-like bird; precocial young
Aromatization is essential for defeminization in altricial mammals
o Aromatase is brain is turning T into estradiol (in general aromatase converts
androgens into estrogens; estrogens refer to the larger class of molecules like
Ferrets: neck-grip duration good indicator of amount of male behavior exhibited.
Expt 1: male ferrets and female ferrets, critical period extends into post-birth period.
Manipulations can be made postnatally. Testes removed at 35 PND (pretty late);
Sex-changing fish: can change sex as adults, testes ovaries, reverse. Naturallyoccurring adaptive phenomenon not occurring in other verts.
o E.g. Male bluehead wrasse may have been a female 2 weeks ago. Social
environment determines when sex change
NBL5: Sexual differentiation
Kinds of sex differences
o Sea devil females are huge compared to males, males latch on and live as
Females are usually larger than males in most of the animal kingdom,
exceptions in mammals and birds.
Schlinger labs research on sex differences in behavior and nervous systems: the manakin
o Manakins are birds living in the New World tropics, the central/South American
tropics. New clade of birds that dont live anywhere else. Interesting be
NBL3: Sept. 4 (W) Evolution and hormones; chapter 2 pp. 42-50, 56-57, 63
Tree-thinking: bifurcation points (nodes) characterize extinct animals that gave rise to
new species. Use to infer relationships among nodes that lead to splits. Branches are
MPOA DA and male rat sexual behavior
- How general is this? The phenomenon is also seen in Japanese male quail; Kleitz-Nelson
2010. DA: helping males copulate for at least 200 mil years.
- Has to do with Nitric oxide and how that discovery Viagra.