Module 10

Question 1

Parental investment figures into all 3 life history tradeoffs

Answer 1

• Offspring quality vesus quantity
• Investment in current vs. future reproduction
• Mating effort versus parenting effort

Question 2

Parental Care in Humans

Answer 2

• Human children are expensive
  ~ Large body size and brain size
  ~ Born relatively helpless compared to apes, brain underdeveloped

Question 3

Altricial

Answer 3

• infants are helpless and immobile at birth, require long-term nourishment and other care in order to survive

Question 4

Precocial

Answer 4

• infants are mobile at birth and other senses are well-developed

Question 5

Humans are considered secondarily altricial

Answer 5

• because we are born more helpless than other primates

Question 6

Parental Care in Hunter-Gathers

Answer 6

• Babies spend the majority of time in direct physical contact with a parent
• Babies sleep with parents
• Babies breast-feed for 3-4 years
• Babies breast-feed on demand

Question 7

Bi-parental care (care by both parents)

Answer 7

• Considered a fundamantal adaptation for human reproduction
  ~ For reproduction to proceed successfully at its “normal” pace (one child every 3-4 years) in hunter-gatherer conditions, care from more than one parent is necessary

Question 8

Male care

Answer 8

• Care by males increases offspring survival at the cost of increased opportunities to bear offspring with new females
• Across species, males care is most often seen under 2 conditions
  ~ It is crucial to offspring survival
  ~ Paternity certainty is high

Question 9

IN humans, we can distinguish two types of care

Answer 9

• Direct care

- indirect care

Question 10

Direct care

Answer 10

• Carrying, play, babysitting, feeding. ACtivities that are done specifically for the child

Question 11

Indirect Care

Answer 11

• Providing resources. Involves activitied (hunting, wage earning) that benefit the child but do not require direct interaction

Question 12

Subsistence and Paternal CAre

Answer 12

• hunter-gatherer dads provide intense direct care to offspring, in addition to provisioning
• Once men can accumulate wealth, it becomes easier to “provide” indirectly
• This is also associated with degree of polygyny. Wealth increases ability to care for multiple families. Increases incentive for mate seeking at the cost of direct care

Question 13

How high is paternity certainty in human males

Answer 13

• In cases where a man has a reason to believe he is the father approximately 2-5% cross-culturally
• Sexual division of labor contributes to paternity uncertainty becasue couples are separated for long hours
• This is a low rate compared with other species
• Investment efforts is very high, so this small amount amtters

Question 14

Males are more likely to invest of

Answer 14

• The child is known to be theirs
• The child resembles them
• The mother is thought to be faithful

Question 15

Testosterone

Answer 15

• is key mediator of the trade off between parenting effort and mating effort in males
  ~ High elevated in mating efforts
  ~ Testosterone levels drop when they are parenting or with a partner
  ~ Testosterone stays lower if the man spends more time with the child
  ~ Testosterone stays high in men who are polygynously married = high mating effort
  ~ Testosterone is lower in men who provide direct care, not affected much in men who provide only indirect care

Question 16

Oxytocin

Answer 16

• mother are hormonally primed to invest in new infants
• Hormone oxytocin is released during childbirth and during breastfeeding
• Across a range of species, oxytocin is essential for bonding between mother and infant
• Released when a mother has physical contact with infant or hears her own infant’s cry
• Neurological pathways for oxytocin are influenced by early environments
• Postparum depression associated with reduced ozytocin response to offspring
• May be affected by nursing practices

Question 17

Parent-offspring conflict

Answer 17

• Mother is related to child by 50%
• Mother is related to other offspring by the same amount
• Child is related to itself by 100%
• Child wants maximum resources for itself
• Parent wants offspring to survive, but wants to balance investment
• Examples
  ~ Weaning conflicts
• mothers usually want to wean offspring before offspring are willing
  ~ Placenta
• the fetus produces hormones that manipulate the mother’s metabolism in its favor.Gestational diabetes and preeclampsia can result
  ~ Crying
• Infants are selected to give cries that imply need to elicit preferential care

Question 18

When to terminate investment

Answer 18

• Offspring is likely to thrive without it
• Offspring is unlikely to survive
• Future reproductive prospects are good

Question 19

Mother Nature (A history of Mother, Infants and Natural Selection by Sarah Blaffer Hrdy) (Mother and other by Sarah Blaffer Hrdy)

Answer 19

Books that I might want to read later on in life

Question 20

Infanticide

Answer 20

• In a large number of species, infants are killed by male non-fathers or (rarely) by female non-mothers
• Humans are exceptional in that the majority of infant killing are preformed by the mother herself
• Infanticide is an extremely common, and often non-taboo, occurrence in traditional societies
• It is common for infants not to be considered human being until they have a been named (which can be 2 or more years)

Question 21

Most common reasons for infanticide

Answer 21

- Lack of paternal figure
~ Woman unmarried or divorced
~ Husband dead or at war
- Inadequate resources
~ Twins
~ Economic hardship
~ Born too soon after previous child
~ Too many children
- Inappropriate paternity
~ Incest
~ Adultery
~ Remarriage- infant sired by previous husband
- Signs of poor infant quality
~ Deformed
~ Small
~ Ill
~ Rear appearance

Question 22

19th century Europe

Answer 22

• Maternal workload low, leads to high fecundity
• But financial resources often insufficient to care for children
• Made worse by trend of artificial milks and “wet nursing” by hired girls. Lifted the influence that lactation has on maternal fecundity
• Very successful practices for the wealthy, difficult for the poor

Question 23

Foundlings

Answer 23

-Milan
~ 343,406 children abandoned between 1659-1900
~ In 1875: 91% of illegitimate children abandoned
- Moscow
~ 1880-1889: 15,475 infants abandoned each years on average
- Florence
~ 1840s, 43% of baptized infants abandoned

Question 24

Consistently

Answer 24

• cited for the same reasons as infanticide

~ Especially, lack of a paternal figure, inadequacy of resources

Question 25

“At risk” women are more likely to be pro-choice

Answer 25

• As are members of their families
• As are their political constituencies
• Irrespective of their religious affiliations

Question 26

Sex-biased investment

Answer 26

• When males resources are unevenly distributed, males have high variance in reproductive success because the have secure more mates
  ~ Very successful men + many wives and children
  ~ Leves many men with zeros reproductive success
• Females have a high chance of marrying/ reproducing but little variance
• A successful son will yield many more grandchildren than a successful daughter

Question 27

Sex Biased Investment in India

Answer 27

• Caste system
• Women must marry up in social class = hypergyny
• Brides must bring a dowry appropriate to social status
• Males can have multiple wives

Question 28

China

Answer 28

• One-child policy promoted selective abortion and abandonment of females infants (1979-2015)