Class Notes (811,177)
Canada (494,540)
Psychology (4,104)
PSY398H5 (31)
Lecture 7

Lecture 7 - Male Pregnancy

4 Pages
Unlock Document

University of Toronto Mississauga
Emis Akbari

PSY398H5S – Motivational Systems Lecture 7 – February 21, 2013 Male Pregnancy • Female “ejaculates” eggs to the underside of a male – where he fertilizes them • Carries them for several weeks until they are born as tiny independent young • Male provides nutrients, osmo-regulation and oxygenation • Sex role reversal • Seahorses are monogamous Penguins  Some penguins mate for life, others for just one season  Parents cooperate in caring for the young  During the cold season the mates separate for several  months to protect the egg  Usually the male stays with the egg and keeps it warm  while the female goes to sea to find food for its young  When the female comes back the roles switch  When mothers lose a chick, they sometimes try to steal another mother’s chick  Usually this is unsuccessful – other females come and defend the defending mother Fatherhood  We know very little of paternal behavior  Fathers that report feeling concerned about baby’s cries or report wanting to comfort the baby have higher prolactin levels and lower testosterone levels than less concerned fathers and non-fathers Social Bonding  Animals display a wide variety of social behaviours  Some animals are highly solitary, while others engage in frequent social interactions Social Organization  Monogamy: refers to a social organization in which each partner of a mating pair selectively engages in affiliation and copulation with the other partner  Found in 3-5% of mammals, but slightly higher in primates (Kleiman, 1977)  Other forms of social organization include promiscuity (i.e., an absence of long term social relationships) and polygamy (i.e., multiple mating partners) (Young et al., 1998) What is the Adaptive Significance of Monogamy?  In some species, the formation of long-term pair-bonds is critical for the reproductive success  Both parents are needed for rearing the offspring  If one partner abandoned the family, the offspring would die  The hormones that evoke bonding overlap with those that are involved in reproductive and parental behaviours Monogamy and Bi-Parental Behaviour: Humans  Are humans monogamous? o Sex is not just for reproduction o We display different mating patterns  Are humans bi-parental?  A lot of variation in the amount of care provided by the mother or father PSY398H5S – Motivational Systems Lecture 7 – February 21, 2013  Still, humans form social attachments that include long-term romantic relationships and parental-child bonding Social Boning in Humans  Is there a biological basis to social bonding in humans?  This is difficult to answer but insights have been gained from studies using rodent models of social attachment Rodent Studies: Meet the Vole  Voles (small rodents) are a valuable species for studying the neurobiology of pair bonding o diverse social organization among different vole species o Prarie voles are socially monogamous but montane voles are highly promiscuous (love 'em-and-leave 'em) Prairie Voles  Hamster-sized rodents that form lasting pair bonds with their mates  Males and females nest together & both contribute to the rearing of their offspring  If one of the pair disappear, 70% of prairie voles do not take another partner  The “couple” typically remains together until death Does Testosterone Play A Role in Pair Bonding?  Males of polygamous species tend to have larger testes and higher levels of testosterone than males of monogamous species (by approx. 50%) (Dixson, 1997)  On the other hand, treating male prairie voles with testosterone does not make them polygamous and castrating male montane voles does not make them monogamous (Gaines et al., 1985) Neuropeptides and Pair Bonds  Studies of voles suggest that two neuropeptides play a role in the formation of pair bonds: oxytocin (OT) and vasopressin (AVP) OT and AVP Synthesis and Release  Synthesized in the hypothalamus (paraventricular and supraoptic nuclei)  Released from the pituitary gland into circulation but also project from the hypothalamus to other parts of the brain Background: Oxytocin (OT)  OT is a very abundant neuropeptide and has a wide spectrum of actions both centrally and peripherally  OT is involved in the modulation of many reproductive behaviours and care of the offspring, from neuroendocrine reflexes to complex social interactions  It plays an important role in birth (uterine contraction) and lactation (milk letdown)  Greek: "quick birth" Background: Arginine Vasopressin (AVP)  Also has a wide spectrum of actions centrally and peripherally  Most commonly known for its role as an antidiuretic hormone (i.e., salt balance; conserves body water in kidneys by reducing loss of water in urine) PSY3
More Less

Related notes for PSY398H5

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.