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Terms in this set (41)
Growth seems to be target-seeking. Individuals have genetic potential for reaching full adult stature and if environment allows, we will achieve fullest genetic potential. Reaching this is the goal
Period of above average growth after inhibited growth because of environmental factors
Life history theory
Attempts to explain why certain patterns or sets of traits can be seen as evolving in systematic and predictable ways within and between species
Strategy an organism uses to allocate its energy towards growth, maintenance, reproduction, raising offspring to independence, and avoiding death. Complete life cycle of an organism. Result of optimal allocation patterns, shaped by natural selection
Principle of allocation
The principle that if an organism allocates energy to one function, such as growth or reproduction, it reduces the amount of energy available to other functions. Basic tenet of life history theory
Changes in the brain's neural structure in response to experience during its growth and development
Biological readiness to conceive. Kind of like fertility, but fertility is the realization of capacity to have literal babies. Highly flexible based on environment mother is in, an evolved trait that increases lifetime reproductive success. In highly unpredictable environments, mother might forgo reproduction
Human life history
Characterized by delayed maturation, relatively short interbirth intervals, and a long postreproductive life span
The assumption of life history theory
An adaptive strategy- species adjust their life history traits to local conditions so as to optimize reproductive success
Life history traits that define the tempo of reproduction of a species. Tends to reflect maternal nutritional status, which is determined by the ecology in which the mother lives
First occurrence of menstruation. Start of a woman's reproductive span. Typically occurs 2 years after onset of postnatal breast development and following peak in pubertal growth spurt
The first phase of the ovarian cycle, during which a follicle enlarges and matures. This phase is under the control of FSH from the anterior pituitary, and typically lasts from day 1 to day 14 of the menstrual cycle. The follicle secretes estrogen during this time period.
The third phase of the ovarian cycle, during which a corpus luteum is formed from the remnants of the follicle that has ovulated its oocyte. The corpus luteum secretes progestrone and estrogen during this time period, which typically lasts from day 15 to day 28 of the menstrual cycle. Formation of the corpul luteum is triggered by the same LH surge that triggers ovulation, however in the absence of LH (levels quickly decline after the surge) the corpus luteum begins to degenerate.
Trade-offs of pregnancy
Energetic costs of pregnancy, such as fetal tissue growth, growth and maintenance of supporting maternal tissues, accumulation of maternal fat, and increasing BMR of the growing fetus, enable women to support reproduction on a limited energy supply, but are trade-offs against long-term maternal health and survival
LH, FSH, estradiol, progesterone
Stimulates growth of follicles, and follicles produce estrogen (estradiol)
Stimulates growth of cells in the lining of the uterus, vagina, and cervix. Causes breast to be more receptive to progesterone. Causes changes in cervical mucus. Concentration gradually increases throughout follicular phase.
Changes in cervix and cervical mucus
Around ovulation, cervix opens and fibers line up under influence of estrogen permitting sperm to get through. After ovulation, cervix closes and fibers of mucus tangle up
Secreted by the corpus luteum after ovulation. Helps with the functioning of lining of the uterus in preparation for fertilization. Prepares breasts for possible pregnancy. Signals the pituitary to stop producing LH
What triggers menstruation?
-corpus luteum regresses after about 12 days
-progesterone & estrogen drop off sharply
-endometrium sloughs off
What happens if fertilization does occur?
-corpus luteum remains active
-progesterone levels remain high --> uterine lining remains strong
-hCG from fetus takes over
What is the hormonal signature of the follicular phase?
High E levels, low P levels
What is the hormonal signature of the luteal phase?
High P levels
What is the hormonal signature of the first day of menstrual bleeding?
Low E, low P
What is the hormonal signature of the peri-ovulatory period?
Low E, low P
Factors that affect ovarian function
Age, nutrition, physical activity, psychological stress
Weight loss & progesterone
-Women losing weight had lower progesterone levels than controls
-Small levels of weight loss can lead to luteal suppression
-Significant in the cycle immediately after weight loss
The fluctuation between calories taken in and calories expended
The difference between energy intake and energy expenditure
Women in non-western societies have lower absolute hormone levels, yet they have high fertility
Hormonal Set-Points Hypothesis
-Hormonal characteristics at menarche are carried later in life
-The conditions of development affect the hormonal trajectory
-The absolute level of hormones needed to ovulate may differ between populations
Life history theory & women's reproductive health
Variation in adult levels of reproductive hormones occurs as a consequence of differences in chronic energy availability during growth and development which results in diverse maturation tempos and the establishment of different adult physiological set points for regulation of the HPO axis
Adverse energetic conditions during development that result in slow growth and delayed reproductive maturation lead to lower baseline levels of ovarian function and heightened ovarian sensitivity to ecological factors throughout life
Production of sperm
Hypothalamic pituitary ovarian axis, the main hormonal feedback pathway responsible for the reproductive system
Once males became capable of maintaining high status and reproductive access beyond their peak physical condition, selection favored the extension of maximum life span in males. Selection was on the X chromosome, which then got passed on to females. An explanation for long postreproductive lives in humans
Embodied Capital Hypothesis
Humans invest in brain-based capital, which yield high returns later in life. A prolonged lifespan is necessary for reaping the rewards of those investments
By having grandmothers around, they can help take the burden off of the mothers. So they act as an extra set of hands, helping the mom have more babies potentially. Therefore families with genes that live longer were selected for
Red Queen Hypothesis
Organisms must constantly adapt and evolve to survive in an ever-changing environment (pathogens). Evolutionary arms race. Syphilis had to evolve so people would still want to reproduce with people who had syphilis
A lack of early childhood exposure to pathogens (bacteria, parasites, and other infectious agents) increases susceptibility to allergies and autoimmune diseases by inhibiting the natural development of the immune system. Might be outdated
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