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Human evolution > Wek 14: Menopause/senescence/death and evolution/ethics > Flashcards

Wek 14: Menopause/senescence/death and evolution/ethics Flashcards

(53 cards)

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1
Q

why do we die? (2)

A
  • extrinsic mortality
  • intrinsic mortality
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1
Q

extrinsic mortality (4)

A
  • Infectious disease
  • Predation
  • Fighting
  • Accidents
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2
Q

intrinsic mortality (2)

A
  • Non-infectious diseases ⇒ cancers, dementia
  • Senescence ⇒ things gradually stop working
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3
Q

Senescence

A

organ systems gradually deteriorate ⇒ latin senex = old man
- Skin dies, becomes wrinkled
- Hair becomes brittle
- Overall loss of muscle mass and flexibility
- Bones lose mass and become brittle
- Reaction time slows down
- Various brain functions decline

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4
Q

how do human lifespans change over time?

A

based on intrinsic and extrinsic factors

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5
Q

do we have the ability to stop senescence?

A

no

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6
Q

what do high protein diets lead to?

A

shorter lifespans ⇒ can be used for reproduction and building muscles but not used on DNA repair

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7
Q

Intrinsic mortality

A

things causing death inside the body

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8
Q

how do we guard against intrinsic mortality which takes effort and energy? (3)

A
  • DNA repair to prevent cancerous mutations
  • Immune system function to prevent cancerous growths
  • Antioxidant enzymes
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9
Q

what do bodies spend energy on aside from intrinsic mortality? (2)

A
  • Growth
  • Reproduction
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10
Q

what are trade offs in living longer?

A

Maintenance vs growth vs reproduction

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11
Q

Life history theory and mortality

A

organisms invest just enough in preservation to live just about as long as extrinsic mortality would normally allow

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12
Q

when is there a lot of adaptation to survival for organisms?

A

there should be a lot of adaptation to survival that can benefit the organism from birth to maturity ⇒ once reaching sexual maturity and individuals start reproducing there is still natural selection, but the strength of that is declining
- may be from inclusive fitness where you gain from leaving your offspring in the population and smaller amount of fitness by helping kin ⇒ preservation of shared alleles

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13
Q

when are there typically high mortality rates in many species?

A

early in life ⇒ prior to maturity

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14
Q

what is fitness relative to?

A

other individuals in the population

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15
Q

what ages does natural selection act more weakly on?

A

older life stages
- natural selection acts more strongly on early life stages ⇒ during periods of growth and reproduction

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16
Q

how does body size affect life span?

A

larger animals tend to live longer
- some small animals tend to live unusually long => bats, birds, primates, etc.
- this requires a special trick that reduces extrinsic mortality => wings, shells, living in trees, fire/weapons

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17
Q

is weaker selection on older ages more or less extreme in wild populations than domesticated ones?

A

more extreme

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18
Q

what is senescence the result of?

A

extreme pleiotropy
- Single genes having multiple effects and many genes involved in senescence ⇒ can’t just fix one allele and cure aging
- A single fix is unlikely to solve the problem
- immortality would require massive cellular level interventions => DNA repair

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19
Q

can stem cells get exhausted?

A

yes ⇒ limits ability to achieve immortality

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20
Q

T/F men and women both experience reproductive senescence

A

True
- men have a decline in testosterone and sperm production about 1% per year for testosterone and women have a dramatic decline in estrogen
- women experience reproductive senescence earlier than men

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21
Q

menopause

Study These Flashcards
A

Ovaries shut down (45-55)
- End of egg production ⇒ follicle maturation
- Dramatic reduction in estrogen and progesterone production
- Greek for mono = month and pausis = pause, cessation

22
Q

why does menopause occur? (2)

Study These Flashcards
A
  • women run out of eggs
  • eggs get too old
23
Q

how many egg follicles do women have at gestation?

Study These Flashcards
A

> 250,000-300,000 at the 5 month mark in gestation
- declines throughout gestation but 1,000 left in reserve at birth

24
how many follicles mature during each monthly cycle?
Per monthly cycle only a few follicles are matured and only 1 can become a blastocyst - Other simultaneous mature follicles are rejected by the body - Women typically will have about 450 cycles once reaching sexual maturity
25
why don't women produce more eggs?
we don’t know why we can’t create more molecules but it could have something to do with age of the eggs
26
stages of menopause (4)
- Premenopausal ⇒ maturation to 35-45 - Perimenopause ⇒ 35-45 from last regular period to last period => symptoms associated with menopause culturally from wildly fluctuating estrogen levels - Menopause ⇒ lasts for the 12 months after their last period - Postmenopause ⇒ after last 12 months to end of life with low estrogen
27
Grandmother hypothesis
women stop reproducing early to ensure survival of grandchildren
28
what are the problems with the grandmother hypothesis? (3)
- Why not keep making your own babies? - How often do/did hunter gatherers live to be grandparents? ⇒ if old age is rare, selection will be weak - Female dispersal (widespread in human societies) means that grandmothers are unlikely to live with their daughters children ⇒ paternity uncertainty makes it riskier to invest in sons children
29
does grandmother survivalship affect that of their grandchildren?
grandmother survivorship doesn’t affect survivorship of grandkids of baboons and lions - there is no effect as to whether the grandmother is alive in terms of investing in her grandchildren vs her own children - For lions there was a small effect if grandmother is still reproducing ⇒ likely a group effect from larger group size producing food security
30
mother hypothesis
mom should live long enough to ensure survival of last offspring
31
does mother presence affect the survivorship of offspring?
yes - for baboons and lions in the first year (second for baboons) there is a huge effect on whether the offspring survives ⇒ makes sense since offspring are dependent - After the second year there is no effect and afterward if mom is dead or not or reproducing doesn’t matter - Mom is necessary for survival in the first years of life
32
what does human menopause result in?
prolonged childhood - mothers need to ensure survival of last child
33
darwinian principles (6)
- Have as many children as possible - Have sex whenever doing so might help you have more children - Men have as many affairs with fertile women as possible - Women do whatever it takes to acquire good genes and the resources needed to raise children => Or better yet, get someone else to raise your children - Donate your sperm and eggs as often as possible - Anything that enables you to maximize your reproductive success is justified
34
how does higher education affect fertility?
higher education leads to reduced fertility - education tends to help young people avoid teenage pregnancies and reduce their lifetime fertility - environmentalists worry about the negative effects of overpopulation and therefore encourage people to reduce their fertility
35
36
what are chimpanzee ethics? (6)
- Compete for status - Might makes right ⇒ biggest and strongest get the best food and matings/offspring - Take what you want, by force if necessary - Mate promiscuously - Kill the offspring of rivals if you can get away with it - Kill any out group males you encounter, if you have sufficient strength of numbers
37
what are differences between humans and chimps? (5)
- Marriage rather than promiscuous mating ⇒ the alpha male monopolizes in promiscuous or free love situations - Paternal care ⇒ many human dads are caring and helpful in ways unusual for mammals - Lower rates of within-group physical aggression - Possibility for peaceful intergroup relations - Elaboration of ethical rules
38
is it possiblewe are inclined by nature to be cooperative and concerned for others?
yes - Our success as a species depends on our capacity to find mutually beneficial solutions to competitive problems - We may have evolved to be cooperative and that is in our nature
39
is tit for tat the way out of the prisoners dilemma game?
sometimes but instead of changing the strategies for the prisoner's dilemma we change the payoffs ⇒ likely what has happened over human evolution because games have changed by shifting the payoff structure to play mutualism instead of zero sum win/lose game
40
when females are more locked in to parental investment what can males do?
defect at more opportunities
41
T/F increasing male exploitation of females is a trend in mammalian evolution?
True - female parental investment frees males to invest in mating effort - Competition with other males - Coercion of females ⇒ constrain female choice of mating with other males
42
what mammals are typically in social groups?
females with offspring with few exceptions - most male mammals exploit female parental effort while providing nothing but genes
43
what are the benefits of human monogamy?
married men and women provide mutual economic and reproductive benefits - cooperative to a degree not seen in other primates - human males are unusual in providing extensive parental care - this reverses >300 million year trend in synapsids toward treater parental investment by females - Human food sharing is explicit, routine, and expected which helps maintain societal relationships
44
what are consequences of human men with more paternity confidence? (3)
- More likely to stay married - Spent more time with their kids - More extensively involved in child’s education
45
what happens with lower confidence in paternity for relationships?
the lower the confidence in paternity, the shorter time to dissolution of a union after the birth of a child - If males do not stay with the female after birth they have low paternity certainty
46
what does monogamy and paternal care do for fitness?
provide direct fitness benefits to both parents ⇒ weighted by paternity certainty - Increases offspring survival - Reduces interbirth interval ⇒ 2-4 years without contraceptives - Would not be possible without paternal investment ⇒ calories, protection, labor - Increases human fertility compared to chimpanzees
47
Mutualistic psychology
adaptations that made marriage possible involved profound changes in human psychology ⇒ mindset of cooperation that is not just a product of culture but has evolved
48
what are examples of mutualistic psychology? (5)
- Collect food to share rather than gather food for own consumption (unusual) - Reproductive restraint despite living within a multi-male, multi female society - Self control - Longer time horizon for decision making ⇒ not starting war with neighboring communities - Propensity to consider and care for others
49
what species is a huge proportion of humans livestock?
cattle
50
what did mutualistic interactions with plants and animals enables humans to do?
grow at unprecedented pace and take over the entire planet - now as human population threatened the global ecosystem, selfish human fertility decisions are causing global demographic transition to lower fertility - we have already passed peak population growth rate ⇒ rate itself has declined
51
optimization
people don't seek to maximize reproductive success they seek to optimize reproductive success - trade offs in urban ecology make it expensive to have many kids - advances in medicine and sanitation make it unnecessary to have kids - can ensure lineage survival with just over 2 kids
52
end card
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Human evolution (12 decks)

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