Wk 9 - Grandmothers

Question 1

Small population sizes can impact cultural transmission because…(x4)
Eg…(x2)

Answer 1

Finite populations = number of people adopting a variant is affected by sampling variation
So cultural variants be lost when practitioners are not imitated
Random losses greater in small populations
Also … smaller pool of experts
Isolated Polar Inuit lost kayaks, the leister and the bow and arrow during a plague, but
Skills were reintroduced by long-distance migration

Question 2

Kline and Boyd (2010) conducted a study into tool use/complexity involving…)x4)
Finding…(x3)

Answer 2

Ethnographic comparison of tools, complexity, pop size and rate of outside contact
Increased breadth of tools with pop size, and
High contact/small pop = above mean, while
Low contact/low pop = below

Question 3

Kline and Boyd (2010) concluded that rate of contact was crucial, because…(x2)

Answer 3

Get new ideas when distinct communities come together, and

Share methods they’ve used for X time

Question 4

Hill et al (2011) have argued that the dominance of homo sapiens and the production of cumulative culture are due to….(x3)

Answer 4

Social learning mechanisms that evolved due to
Frequent interaction between large groups, leading to
Metagroup social structures that are not seen in other species

Question 5

If you track through evolution, there is a coincidence of cumulative culture factors around the middle Pleistocene…(x4)

Answer 5

End of erectus
Emergence of neanderthalensis
Long distance tool flows
Increased social network size

Question 6

Shennan et al (2010) compared models with archaeological records, using…(x1)
Finding that population densities…(x2)
So perhaps it wasn’t an increase in intelligence that separates us, but a function of…(x1)

Answer 6

Genetic data from living people to estimate ancient population sizes
During Europe’s cultural flowering 40kya were reached in Africa about 100kya —
Not long before cultural complexity arose there
There being more of us, hanging out more

Question 7

Powell et al (2009) conducted a computer model study into the impact of population size on cultural accumulation, finding that…(x5)

Answer 7

Larger groups = higher probability of improving innovations
Individuals in big groups had a better chance of learning
Bigger populations + more migration = more cultural accumulation
Smaller, more isolated actually lost culture
Emergence of cumulative culture, through imperfect learning

Question 8

Derex et al (2013) expanded on computer modelling of the emergence of cumulative culture, in study involving…(x3)
Finding…(x3)

Answer 8

Ps in groups, maximising ‘health’ by making arrowhead - easier, but less effective, or
Fishing net - harder, better
Had access to ‘cultural’ demos at first, then just other group members
Maintenance of simple task increases with group size
Similar to complex task and maintenance of cultural diversity
Groups of two drifting toward losing the skill altogether

Question 9

Muthukrishna et al (2014) conducted transmission chain study into cultural info transfer, involving…(x2)
Finding…(x2)

Answer 9

Computer building of celtic knot image
Chains of up to ten, learning from 1 or 5
When 5, skill improves with ‘generations’
When 1, it declines

Question 10

Cooperative breeding is…(x1)
And is present in…(eg x1, plus describe x3)
Cooperative breeders are also the only ones that show anything like..(x1)

Answer 10

Any breeding system in which individuals other than parents (alloparents) help to care and provision offspring
Callitrichids - marmosets and tamarins:
High levels of social tolerance
Highly responsive to signals from other group members
Where there’s resource sharing, those who don’t contribute, don’t suffer for it
Rudimentary teaching practices

Question 11

Burkart et al (2009) conducted meta-analysis mesuring strength against extent of prosociality, involving…(x3)
Finding…(x5)

Answer 11

Cooperative breeders - Homo sapiens, callitrichids; and not - cebus (macaques), pan (chimps)
Data mostly on sharing of food,
With either closely bonded kin/non-kin, fellow group members, anonymous group members, true strangers
Chimps are rubbish at sharing across all opportunities
Cebus do closely bondeds, but not others
Homo and calli on par until big drop for calli in anonymous group member sharing
Sharing with anonymous group members is big point of distinction of humans – need for group membership
No one shares with true strangers

Question 12

Prosocial behaviours are…(x1)
And may function…(x2)
And be motivated by…(4)

Answer 12

Those designed to benefit others
In many different ways - altruistically, future benefits etc
Spontaneous helping impulse
Psych processes - evaluation of own future/reciprocity
Harassment/intimidation by recipient
Socially tolerated theft/begging by recipient

Question 13

Cooperative breeding increases opportunities for social learning due to…(x3)

Answer 13

Multiple, highly tolerant role models
Potentially longer juvenile periods, leading to
Expansion of individual skillset

Question 14

An adaptation of Trivers (1972) theory of parental investment applies to grandparents in that…(X2)

Answer 14

Resources that grandparents transfer to their grandchildren, or that benefit the grandchild, exact opportunity costs
Eg practical help, food production, finances etc

Question 15

The Grandmother Hypothesis is that…(x1)

Answer 15

Menopause may have evolved because the benefits of care provision outweigh costs of further reproduction

Question 16

Hawkes et al (2008) found that grandmothers…(x1)

Answer 16

Help offspring leave more descendants than mothers whose own mothers are not longer around

Question 17

Sear and Mace (2008) meta-analysis of the impact of grandmothers found…(x1)

Answer 17

Presence of a maternal grandmother was associated with an increase in her grandchildren’s probability of surviving the high-risk times of infancy and childhood

Question 18

Hunter-gatherer societies have formed 90% of the last 100K years, with women…(x1)

Answer 18

No longer capable of reproducing frequently making valuable contributions to the survival of grandchildren

Question 19

Hawkes et al (1997) analysed…(x3)

And found, eg (x4)

Answer 19

Mother’s role in provisioning weaned offspring,
Effect of a new baby on other offspring, and
Grandmother’s role
Post-menopausal women responsible for nearly 40% of food acquisition (less than 30% by breeding age women, only outstripped by adolescent males)
As children get heavier, need more food, correlates with mothers foraging time – costs of having a baby
Age and foraging time highly correlated
Grandmothers less likely to forage with increasing age of child

Question 20

Kaptijn et al (2010) studied contemporary Dutch levels of…(x1)
Finding…(x2)
And predicting probabilities of…(x2)

Answer 20

Different grandparental care relative to un/employed daughters
Where there’s often care it’s grandmothers, maternal -
Aligns with reduced hours by mother
Adding to the family for a child who never receives grandparental childcare support is 35%
Doubles to 66% if you get support

Question 21

Johow et al (2011) showed that it’s maternal grandmothers that make the difference, in study that found…(x1)

Answer 21

Paternal grandmother presence lengthens the inter-birth interval

Question 22

Summarise the value of grandma (x4)

Answer 22

Contribute economic and social resources to their descendants,
Increasing the number of offspring their children can have and the survivorship of their grandchildren
Reinforce complex social connections
Transmit skills and cultural knowledge from environmental (what plants are poisonous) to technological (how to knap a stone knife)

Question 23

Kim et al 2012 showed a significantly longer lifespan…(x1)

Answer 23

With grandmothering than without

Question 24

Caspari (2011) looked at the dentin of 70 different Neanderthal individuals, finding that…(x1)
Which means that there could not have been…(x1)
With similar patterns found in…(x1)

Answer 24

None survived past 30 yrs
Grandmothers
homo Heidelbergensis from Spain

Question 25

Caspari and Lee (2004) tested four hominid groups, comparing the ratio of old/young individuals in…(x4)
Finding…(x1)

Answer 25

Later Australopithecines, early and middle Pleistocene non, neandertals, and post-neandertal early upper Paleolithic Europeans
West Asian and European Neandertals, and West Asian early modern humans did not have a significant presence of grandmothers

Question 26

Hawkes et al (1998) concluded that the distinctly human behaviours and life-history appeared…(x1)
Coinciding with…(x1)
Due to the emergence of something that earlier hominids lacked…(x2)

Answer 26

Around 50kya
Unprecedented ecological and competitive success
Long postmenopausal lifespans and the associated population dynamics underwritten by grandmothers

Question 27

What is another speculative outcome from the presence of grandmothers? (x7)

Answer 27

If we take grandmothers out of equation, mums left with the kids
Foraging still needs to happen – need kids near you, protect from prey etc
If there’s grandma, she either forages or babysits
Kids can stay in camp, not at risk
Allows you to put children together – allows for play and engagement in larger numbers
Facilitating emergence of pretence…
Layering on more factors that point us to cumulative culture

Question 28

Hill et al (2011) conducted comparison of population composition of 32 societies, finding…(x2)
Which supports the value of…(x1)

Answer 28

Primary kin generally make up less than 10% of a residential group
Groups were mainly composed of individuals either distantly related by kinship/marriage, or totally unrelated
Interacting populations

Question 29

Regarding imperfect learnign processes, Powell et al (2009) assert that…(x3)

Answer 29

Each individual possesses ability in some cultural skill/domain
All try to learn from most skilled, but imperfect learning can lead to loss of skill
But, errors in transmission can also mean some acquire greater value than their model