Lecture 8? Human reproductive ecology 2 Flashcards
What is the pathology paradigm
- human reproduction has a fundamental paradox: although it is critical to the survival of the species, the process is relatively inefficient
what is an alternative view to the pathology paradigm
adaptationist paradigm
what is the adaptationist paradigm
reproductive losses are not reproductive failures
- suppression mechanisms -> regulate timing of reproductive events
true or false - all conditions are equally good to invest in reproduction
false - the ability to interrupt reproduction can provide a selective advantage
preventing reproduction during inauspicious times is hypothesized to allow females to focus resources on
- surviving bad times
- help existing offspring survive
- avoid investing in offspring with reduced fitness prospects
- improve overall condition to invest in future offspring
What is Peter Ellison’s view on reproductive function
energy as ultimate modulator of reproductive function
What is Peter Ellisons model of reproductive function and energy
social environment, constitutional genetic factors, and physical environment interact and lead to energy availability –> reproductive function
The probability of conceiving, delivering and raising a child can be reduced at different stages
- pre-conception behaviour (coitus avoidance)
- anovulation - not releasing an egg/not ovulating
- miscarriage
- post-conception behaviour (neglect, abandonment, infanticide)
What do progesterone and estrogen do
thicken uterine lining
What are proximate explanations of fecundity when energy balance is positive
positive energy balance leads to greater insulin and greater fat storage and greater ovarian function
What are proximate explanations of fecundity when energy balance is negative
negative energy balance leads to increased cortisol and lower fat storage and decreased ovarian function
what is energy status
stored energy
what is energy balance
intake - expenditure
what is energy flux
energy turnover (bank analogy)
seasons are…..
a good predictor of energy availability and expenditures
in a small village in rural Poland fall and winter months characterized by
- low physical demands, no agricultural work
- harvest and haying in summer, greater expenditure
- progesterone levels lower in summer - ovarian suppression
who is Wenda Trevathan
- evolution of human birth process and its consequences
When did bipedalism emerge
6-4 mya in homininds
- positive selection for bipedalism =changes in how give birth
what is sagittal plane
cut someone in two equal halves
what is coronal plane
cut someone into front and back halve
what is transverse plane
cut someone at centre
what is the birthing process in quadrupeds
- entrance and exit of birth canals are oriented front to back (sagittaly) (similar in primates)
birthing process in humans
- birth canal twisted in middle
- inlet is broadest in transverse and outlet is in the sagittal
- maximum breadths of entrance and exit of
birth canal are perpendicular to each other - human infant head largest in sagittal, shoulders broader in coronal
- pelvic’s inlet and outlet planes are perpendicular
*head rotations
What would be the risks for human babies if mothers adhere to standard primate birthing process
- break neck
summary of human birth
- babies born usually facing away from mom
- increased risk if give birth alone
- argued human birth becoming a social enterprise
Labor and delivery in clinical settings has increased risk for
- use of drugs
- use of fetal monitoring
- posture for about and delivery
- concern with contamination
- episiotomy
- c section
- *CHANGES IN SOCIAL ENVIRONMENT
what does the change in social environment giving birth mean?
potential mismatch between evolved needs of women during labour and the contemporary medical system
What are interventions for mismatch between evolved needs during labour and medical system?
- work with midwife
- add a doula
What do midwives and doulas add
emotional and social support —-> more positive feelings, self esteem, better obstetric outcomes, increased breastfeeding
What is required for successful reproduction
- energy
- social support
- logistic support
- appropriate health status
- economic resources
How does the body identify inauspicious times for reproduction
- physiologic alarm triggered by effect of those inauspicious times or anxiety generated by the prospect of future inauspicious times
- **STRESS
limits of previous studies on stress and female reproduction
experimental stress + specific stressors (ex: athletes) do not equal real life stress?
what is the definition of real life stress
the combination of all daily stressors faced by individuals in the course of their lives
What is a model of real life stress
energetic stressors, psychosocial stressors, health stressors interact with each other and lead to cortisol
What were Pablo’s predictions in menstrual cycle and early pregnancy and cortisol
- increased cortisol = deleterious changes in profiles of reproductive hormones during menstrual cycle
- increased cortisol during placentation period (3 weeks) will be associated with pregnancy loss
Why is the first three weeks of gestation important
- placentation = period of critical vulnerability for fetus in terms of maternal stress
- mother fetus conflict during placentation
Before placentation ovarian steroids produced by ……. are crucial for ………
corpus luteum….maintanence of pregnancy
3 weeks after conception the ……. matures and ……… replace ……. as main source of steroids
placenta, embryonic tissue, CL
maternal energetic investment and risks associated with pregnancy increase dramatically after placentation…. meaning….
the first 3 weeks of gestation might be the last window of opportunity where a woman’s body can interrupt a pregnancy relatively easily and cheaply
what was Pablo’s study population
- high ethnic and SE homogeneity
- low use of modern contraceptives
- smaller towns
What was Pablo’s methodology
- participants - porous, nominally fertile and married
- 3 morning visits/week
- morning urine and interview
- 12 months of data collection
what did Pablo’s study find
- increased cortisol - untimely increases in progesterone during follicular phase (associated with reduced chance of conception)
- increased cortisol - untimely increases in gonadotrophin (LH and FSH) both during the follicular and luteal phases (negatively affect ovulatory and luteinization processes)
summary of Pablos study
- increased cortisol - deleterious changes in FSH, LH, estrogen, progesterone
- within first 21 days after conception higher cortisol = higher risk of spontaneous abortion
- ‘real life’ stressors associated with reproductive suppression in women
