med lec 6.docx

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17 Apr 2012
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Nutrition 2/16/2012 8:15:00 AM
-differences between male and female life histories
alternative allocation
-additional variation in response to environmental cues
-linking nutrition to growth and maturation
-“developmental origins of adult disease” ;programming
-transgenerational effects
-special significance of girl child and women’s nutrition
-significance of secular trends in life history patterns
Puberty vs. adolescence
Onset reproduction function
Period between appearance of secondary sexual characteristics and
completion of skeletal growth
Cultural markers for attainment of adulthood may or may not be
linked to a biological marker
Alternate allocation strategy
Survival variation: sex + environment
Puberty in females: fat increases
o Males increase in muscle mass
Nutrition:
Differences between male and female life histories
Unique derived characteristics
We can characterize genders
Males and females use nutrients differently
Alternative allocation of energy and nutrients
Early life nutrition has a gigantic effect on later life (ie from fetal life)
This is called programming
Humans have adaptations to fine-tune metabolic adaptations for later life
Problems with this:
Later environment may be different from earlier life. ie
over-nutrition/ under-nutrition
Additional variation in response to environmental cause
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Linking nutrition to growth ad maturation
?Developmental origins of adult disease?; programming
Transgenerational effects
Special significance of girl child and women?s nutrition
Powerful effects of nutrition across generations
Helping girls and women with nutrition (like in Africa) can have
profound effects
Significance of secular trends in life history patterns
ie height
Variation across individuals as well as over time
- All organisms maximize their transmission of genes
Metabolic adaptations
Puberty vs adolescence
PUBERTY: the onset of reproductive function
ADOLESCENCE: ?murky? period between appearance of secondary sexual
characteristics and completion of skeletal growth
Cultural markers for attainment of adulthood may or may not be linked
to a biological marker
- One key measure that marks the end of adolescence and
beginning of adulthood is skeletal growth
Menstruation, driving license, legal age to drink are all cultural
markers of adulthood.
GROWTH: size, physique, composition (bone, muscle), systematic
MATURATION: the process of changes in skeletal, sexual, somatic,
neuromuscular
DEVELOPMENT: has to do with cognitive, emotional, social competence,
motor skills
All of these come together with self-concept and perceived competence
Key differences between female and male life histories:
Females experience menopause while males continuously produce sperm
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Females start puberty before males. Onset of reproductive function is
earlier for females
Hormonal triggers for males are only a few months behind females, not
that large of a difference
Phenotypic scheduling is slower for males though
First birth average is earlier for females than for males
Occurs a lot in natural fertility populations (means no birth control)
On average, females survive longer than males
Variation in mortality
Life expectancy is around 83 in Canada while it is in the low 30s in Africa
Sex and environment contribute hugely to survival:
Consistent differences among ages:
Males are more likely to die for any birthweight than females
Males have a higher annual risk of death
In every country there is an appreciable difference in average lifespan
There is a biological vulnerability to being a male
Theory: males are evolved to trade-off risks of death against
something else that perhaps correlated more strongly to fitness or
genetic success
- SURVIVAL VARIATION: sex + environment
Maximizing reproductive success for females:
- In great conditions you can live a long life with many offspring
Early maturity
Good access to nutrients
Low risks of disease and death
Can start reproducing soon
High conception success
In poor conditions:
Delayed maturity
Pregnancy failures
Ill-fed offspring, low survival
Early death
Smaller mothers can face high risk in terms of construction
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