HSCI 216 Lecture Notes - Lecture 4: Coevolution, Late-Onset Hypogonadism, Life Table
28 May 2018
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HSCI 216 May 16,2018
Nature vs. Nurture
- Nature: Our genetics determine our behavior: Our personality traits and abilities are in
our ature
- Nurture: Our environment upbringing, and life experiences determine out behaviour.
We are urtured to ehae i ertai as.
Is that why adolescent girls are sub-fertile?
- Female fecundity seems to track the growth of the pelvis
- Full fertility achieved about 5 years after menarche (average 12.7 years old)
- Earlier births involve higher risks
o E.g. LBW, prematurity and birth complication associated with narrow birth canals
Reproductive maturity
- Optimal allocation implies trade-offs.
- 2 Fundamental Trade-offs:
o Current vs. Future reproduction
▪ Postponing reproduction due to education (or for a better time)
▪ Cost of reprodutio
▪ As the species/ population level, this determines major demographic
patterns (age at first reproduction, inter- birth intervals, fertility rate)
o Quantity vs Quality
▪ Infant mortality: if it is high, females will produce more kids
▪ Education
▪ Many cheap offspring or few expensive ones
▪ As the species/ population level, this determines life history traits such as
duration of lactation, duration of the juvenile stage, total fertility
▪ Lack’s effect: optimal number of chicks: intermediate brood size leading
to the highest number of surviving offspring
▪ Blurton Jones’ study: optimal interbirth interval among the !Kung:
iterirth iteral IBI that led to the highest uer of suriig offsprig…
- Timing and intensity of reproduction has consequences for both mom and children
Aging
- “eesee is assoiated ith a road rage of hages…
o Hormones
o Immune system
o CDV
o Body composition
o Bone
o Brain Function
o Reproductive system
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HSCI 216 May 16,2018
▪ Menopause
▪ Andropause
Why Senescence?
o Listen to talk by Dr. Patridge to explore that (Questions in Exam!)
Why stop reproducing?
Why menopause? (Lady)
Three Hypotheses:
o Follicular depletion (Proximate) – Ho? Mehais
▪ Follicles get used up
▪ 50 years of age: a mammalian limit?
o Timing of senescence (Ultimate)—Why?
▪ Human take long time to raise a child
▪ End of reproduction set feale’s age speifi life epeta ad
duration of infant dependency
▪ Ape continue to reproduce
▪ Human may get kin to help raise offspring
o Grandmother Hypothesis (Ultimate)
▪ As mother age, the costs of reproducing become greater, the energy
devoted to those activities would be better spent helping her offspring in
their reproductive efforts
▪ Redirecting their energy to their offspring to ensure the survival of genes
through younger generations.
What about male?
- Alternative explanation: “hift the fous fro the se speifi oe to the speies’
long post-reproductive life
- Male do not invest much in their offspring (no menopause)
- You will have to be a good mom to raise your kid but male only needs sperm to
reproduce.
- Selection for Life Span
o Gradother’s productivity (Hawkes et al.)
▪ Evolution of the human long post-reproductive life
• Gradother’s produtiit led to seletio for irease lifespa
o The Patriarch Hypothesis
▪ This ability in human males to keep reproducing after their physical prime
ould ….
▪ Problem?
• Sex-biased explanation (Like Grandmother hypothesis)
• When did less strength-based skill evolve?
o Embodied Capital Hypothesis (ECH) (Kaplan et al.)
▪ Focuses on the co-evolution of brain capacity and longevity
▪ Human….
▪ ….
- Key concepts:
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