Lecture 3 Flashcards

1
Q

What is epigenome

A

Set of chemical marks in an individual’s genome that affects in gene expression. This set of marks is heritable but can be modified by environmental exposures.

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2
Q

What are epigenetic factors

A
  • non coding RNA
  • histone modifications
  • histone variants
  • chromatin remodelling factors
  • DNA methylation
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3
Q

Why is the epigenome necessary for development

A
  • cell differentiation
  • tissue differentiation
  • life history events
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4
Q

What potential adaptive advantage could the epigenome provide

A
  • allows for changes in expression of the otherwise static genome to respond to environmental conditions
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5
Q

epigenetic changes are associated with _____

A

environmental stressors

  • changes are reversible
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6
Q

What is life history theory

A
  • postulates that Ontogeny has been shaped by natural selection
  • organisms are expected to follow resource allocation patterns across their lifespan that result in an optimization of their Overall Biological Fitness
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7
Q

What is ontogeny

A

development from the moment of conception

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8
Q

What is overall fitness

A

individual fitness + inclusive fitness

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9
Q

What is individual fitness

A

Offspring produced by self

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10
Q

What is inclusive fitness

A

positive? effect on the fitness of relatives

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11
Q

What is the formula to calculate trait would have positive selective value

A
  • Hamilton
  • rb> c
    c - reproductive cost to self
    b- reproductive benefit to recipient
    r- coefficient of relatedness
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12
Q

How do individuals maximize fitness

A

by optimizing resource allocation throughout life span

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13
Q

What is the principle of allocation

A

at any given life stage resources used for one purpose cannot be used for another

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14
Q

How does natural selection relate to principle of allocation

A

ns expected to favour evolution of optimal allocation patterns

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15
Q

What do we need to allocate energy to

A
  • growth
  • maintenance
  • reproduction
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16
Q

What are the human life stages

A
  • prenatal
  • childhood
  • adolescence
  • reproductive life
  • post-reproductive life: menopause and andropause
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17
Q

What is senescence

A
  • end of childbearing to death
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18
Q

Why are most nonsocial mammals weaned into independence while humans are dependent post weaning

A
  • early human diet is particular… digestive system matures slowly but energetic demands are substantial
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19
Q

Why is human childhood particular

A
  • relatively small body size
  • comparatively slow and steady rate of growth
  • dependent feeding
  • Higher RMRs than any other mammalian species
  • large expensive fast growing brain
  • motor and cognitive immaturity
  • adrenarche (shared with chimps) and mid-growth spurt (unique to humans)
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20
Q

What differentiates humans from apes

A

in humans delays in
- eruption of first permanent molar
- menarche
- first birth
- shorter birth intervals
- can rear multiple offspring simultaneously

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21
Q

What do short IBIs in humans provide

A

reproductive advantage over other apes because we can produce and rear 2 offspring through infancy in time it takes chimps or orangutans to produce and rear one offspring

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22
Q

Why can we rear multiple offspring simultaneously

A

other people can feed child -> reduction of period of lactation -> reduction of IBI -> greater life time fertility for mom

23
Q

What explains human childhood

A

more time for developmental plasticity -> more precise tracking of socio-ecological conditions -> greater offspring survival rate -> greater life time fertility for offspring

24
Q

What is special about human adolescence

A
  • growth rate is quantitatively different in terms of amount, rate, and duration of growth
  • length of time between age at puberty and age at first birth ~10
25
Q

Why is the age of viable sperm - first child delayed?

A
  1. time to learn/practise hypothesis
  2. ecological risk aversion hypothesis
  3. proven value hypothesis
  4. resource accumulation hypothesis
26
Q

What is the learning hypothesis

A
  • brain growth and learning necessary for success
27
Q

What is ecological risk aversion hypothesis

A
  • avoid competing with adults for food and other resources - low profile until ready
28
Q

why do girls experience adolescence

A

practise of parenting skills -> greater lifetime fertility

29
Q

Female fecundity seems to track ____

A

the growth of the pelvis

30
Q

What are two fundamental trade-offs in reproduction

A
  1. current vs future reproduction
  2. Quantity vs Quality
31
Q

What is current vs future reproduction

A
  • cost of reproduction
  • reproduce now or later time?
  • species/pop level, determines major demographic patterns
32
Q

What is quantity vs quality

A

with the same effort: many cheap offspring or few expensive ones
- at species/pop level, determines life history traits such as duration of lactation….

33
Q

What is Lack’s principle

A

optimal number of chicks: intermediate brood size lead to the highest number of surviving offspring

34
Q

What was Blurton Jones’ study

A
  • optimal IBI among !Kung IBI that led to the highest number of surviving offspring for them was also most common IBI in the population
35
Q

____ and _____ has consequences for both moms and children

A
  • timing
  • intensity of reproduction
36
Q

What are changes associated with senescence

A
  • hormones
  • immune system
  • cardiovascular system
  • body composition
  • bones
  • brain function
  • reproductive system (menopause and andropause)
37
Q

What are three hypotheses of menopause

A
  • follicular depletion (proximate)
  • timing of senescence (ultimate)
  • grandmother hypothesis (ultimate)
38
Q

What is timing os senescence hypothesis

A

end of reproduction set by a female’s age specific life expectancy and duration of infant dependency -> reproductive senescence occurs at appropriate age for investment in last offspring

39
Q

What are discussions around timing of senescence hypothesis

A
  • apes continue to reproduce
  • humans may get kin to help raise offspring
40
Q

What is grandmother hypothesis

A
  • selection may have favoured early termination of childbearing in favour of investing in grown children and grandchildren
41
Q

what are discussions around grandmother hypothesis

A
  • isn’t it better to reproduce yourself than help relatives
  • living with maternal kin is not universal
42
Q

What are alternative hypotheses for menopause

A
  • grandmother’s productivity
  • patriarch hypothesis
  • embodied capital (gender neutral)
43
Q

What is grandmother productivity

A

led to selection for increased lifespan - efficient tuber diggers…

44
Q

What is patriarch hypothesis

A
  • shift to less strength based male male competition
  • males can be high status and obtain mates even though not in ‘prime’ physically
  • ability for males to keep reproducing selected for longevity
  • selection on autosomal and passed to females
45
Q

Problems with patriarch hypothesis

A
  • sex biased
  • when did less strength based skills evolve?
46
Q

What is embodied capital hypothesis

A
  • focus on co-evolution of brain capacity and longevity
  • 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
47
Q

Compared to other apes humans have

A
  • extreme brain size
  • prolonged juvenile period
  • intergenerational transfers
  • long life span

**all co-evolved in response to dietary shift

48
Q

humans have specialized on consumption of _______ foods

A

calorie dense, low fibre

49
Q

our intelligence associated with long developmental period

A
  • extended period of prenatal production of cortical neurons
  • extended period of myelination
  • extended period of dendritic development
  • cognitive development not completed until the 20s
  • association with slowed aging of brain
50
Q

expensive brains linked to higher _____but more difficult to acquire ______

A

quality, food resources

51
Q

Humans unique age profile of energy production

A
  • long dependency period
  • energy production peaks in later ages
  • payoffs offset the costs of the prolonged dependency period
  • transgenerational transfers required to support profile
52
Q

Could a species with human productivity and chimp survival profiles prosper

A

no

53
Q

Embodied capital hypothesis

A
  1. exploration of high quality, difficult to acquire resources
  2. high levels of knowledge and skill
  3. large brain and long (and low productivity) period of development
  4. productivity increases with age -> lower mortality rates and greater longevity
  5. compensation of low early productivity during adult period via intergenerational transfers
54
Q

In modern system…. embodied capital determines ____ and ______ that affect __________

A
  • income
  • social capital
  • survival, growth, maintenance, reproduction