Lecture 10 - Sociality

Question 1

What are the benefits of group living?

Answer 1

Predation
Joint foraging
Defence of territory
Care of offspring
Information

Question 2

Under what circumstances is sociality versus non-sociality favoured by natural selection?

Answer 2

Cost of living in a group vs the benefit of living in a group
Makes sense to have more benefits.

Question 3

What is predation

Answer 3

the preying of one animal on others.

Question 4

What are the benefits of living in a group in terms of predation?

Answer 4

• More power in numbers, more eyes looking out for a predator
• Much harder for an eagle to catch a pigeon when they are in groups

Question 5

What are the benefits of group living in terms of joint foraging?

Answer 5

Hunting together is a benefit of living in a group - have access to larger prey
Can target larger prey with larger number of a pack

Trade off if too many, as less food to share
Trade off if too little group, as can’t catch bigger prey

Optimality of 5-6, as can attack larger prey with lots of food/meat to share

Question 6

What are the general costs of group living?

Answer 6

Detected as travel larger distances in packs

Less time spent alert, as feel safer in large groups

Spread of diseases

As group increases, required to move more

Question 7

What are the costs of being in a group - optimal group size?

Answer 7

Optimal group size is shown to be around 3, as one can die and 2 are left to reproduce.
This varies across species

Question 8

What is the relation with stress and group size in lemurs?

Answer 8

Measured cortisol in lemurs in their groups

When in groups of lower individuals, cortisol is high
When in larger groups cortisol is less

Question 9

What are the 5 types of social groups?

Answer 9

Asocial
Monogamy
Polygyny
Various mating systems
Polyandry

Question 10

What is an asocial social group?

Answer 10

Known as promiscuity - just on their own, but mate with everyone
e.g. hedgehog

Question 11

What is a monogamy social group?

Answer 11

One male, one female, and stay together for life. humans!
e.g. gibbon

Question 12

What is polygyny social group?

Answer 12

One male, multiple females (known as female philopatry, where females stay where they are and males travel/disperse to them)
e.g. gorilla

Question 13

What are various mating systems social groups?

Answer 13

Multiple male, multiple female systems
e.g. babbon

Question 14

What is a polyandry social group?

Answer 14

Opposite of polygyny
Female mates with several males, but each male just has one mate
e.g. marmoset

Question 15

What is the social brain hypothesis?

Answer 15

In order to be in a large group, you need to have cognitive abilities to deal with the demands and challenges of staying in a social group.

Shows that monogamous social groups show the largest brain size, solitary shows reduced brain size

Question 16

How does this hypothesis work in primates?

Answer 16

Higher the group size, the larger the cortex levels

Correlation between these two

We have relationships with many groups, so have multiple interactions, not just our mate, so acquire higher cognitive abilities as we have many relationships with many different people

Question 17

What is the social bond/brain hypothesis process?

Answer 17

group size ( beneficial as) -> predation ( we keep this in check) -> late reproduction and long life span (less predation, so more time to reproduce and have longer life span) -> brain size (increases)

if we have food recourses -> Either -> increase group size as we can share it -> increase brain size

Question 18

How is the social brain hypothesis seen in humans?

Answer 18

We have more interactions as we have so many kinds of relationships and longer life spans
expressed through Dunbar’s number

Question 19

What is Dunbar’s number?

Answer 19

The theoretical number of people with whom any one person can maintain a meaningful or stable social relationship, estimated at 150

Dunbar came up with the social bond/brain hypothesis

Question 20

Why do humans have large brain sizes?

Answer 20

We obligate sociality, so explains the brain hypothesis

Question 21

What social groups / systems are seen in humans?

Answer 21

Multimale and multifemale groups with embedded marriage/mating bonds of pairs (monogamy)

And polygyny as through male with multiple females

Question 22

What is virilocality?

Answer 22

Process of wives moving to their husbands families, so wife disperses to the husband that stays in his family and stays “still”,

Also called female dispersal

Question 23

What is uxorilocality?

Answer 23

Husbands moving to their wives families, husband disperses to the wife that stays in her family and stays still

Also known as male dispersal

Question 24

When are animals more social?

Answer 24

When the benefits (e.g. predation reduction, joint ventures, defence of territory, information) exceed the costs of competition for resources.

Question 25

What do close social bonds require?

Answer 25

Brain mechanisms to support them - monogamy favours higher brain size

Question 26

Definition of cooperation

Answer 26

Behaviour that provides a benefit to another individual, maintained because it does so.

Question 27

2 types of cooperation

Answer 27

Mutual benefit behaviour Altruism

Question 28

What is mutual benefit behaviour?

Answer 28

Win win situation Behaviour that benefits the recipient and the actor

Question 29

What is altruism?

Answer 29

Behaviour that benefits another individual but is detrimental to the actor

Question 30

2 requirements for cooperation/mutual benefit behaviours?

Answer 30

1. Shared interest - so can reach a common goal 2. Mechanism of control against cheaters, as can cheat (eating the food without doing any of the hunting) not contributed to the hunt There must be a mechanism to stop these cheaters

Question 31

What is direct reciprocity?

Answer 31

A helps B and B will help A in the future Cost < benefit x probability of the recipient reciprocating in the future Individuals have to repeatedly interact and recognize their recipients

Question 32

What is an example of direct reciprocity in WW1?

Answer 32

Stopped fighting at Christmas, both agreed to not fight or kill - 'let and live system'

Question 33

What is indirect reciprocity?

Answer 33

A helps B and is thereby more likely to be helped by C Seen more in humans, passing the favour on, seen as a nice person so Cost < Benefit x probability of having the correct information about the partners prior behaviour

Question 34

What mechanism controls indirect reciprocity?

Answer 34

Reputation - if seen as a nice person people want to reciprocate back to you - main point of reciprocation is to receive cooperation in the future

Question 35

What is an example of people being concerned with the reputational consequences of their actions?

Answer 35

If your actions are publicly seen, they have a powerful influence/increase on cooperative behaviour. e.g. - people would contribute more money when group members could publicly see their decision, compared to an anonymous decision (i.e. can see their name or face) - People seen to contribute to the fund are more likely to be chosen by others for more cooperation games later on (indirect!!!)

Question 36

What is the link between cooperation and punishment?

Answer 36

When given the opportunity some people will punish uncooperative behaviour

Question 37

What does cooperation require?

Answer 37

Some sort of control mechanism

Question 38

What is cooperation on a large scale essential for?

Answer 38

human ecological success

Question 39

What are 2 examples of social learning?

Answer 39

rats with pinecones - saw one rat open it and then the other rats mimicked this and learnt how to open it Japanese Maquaces - washed the potatoes then the whole population started to wash them

Question 40

How does social learning produce behaviour/cultural traditions?

Answer 40

Chimpanzee use stone to crack nuts, complex for then and is traditionally learnt Songbirds have dialects that are socially learnt

Question 41

Why learn socially, rather than individually?

Answer 41

- High cost of learning individually, so more beneficial socially as less energy is required - Environment is changing constantly, benefit to individual as they can know it and keep up - But is a cost to a group as not all members might know this change in the environment

Question 42

Unlike other animals, some human cultural traditions are cumulative, what is this?

Answer 42

We progress our culture and make all things better Constantly improve everything e.g. airplanes have gotten better functionally ergonomically - known as cultural evolution

Question 43

Can cultural evolution be adaptive evolution?

Answer 43

Yes, as long as cultural acquisition is somehow related to the usefulness of the trait. As long as there is some individual learning going on, as well as social.

Question 44

What is meant by vegistal characteristics?

Answer 44

Things that have been kept from the past, despite no longer needing them. e.g. guards with swords, yet we no longer fight e.g. the sperm whale with femur and pelvis, use to have it when it was a land species, when it evolved into the water this structure stays and now serves no purpose

Question 45

How do humans occupy the "learning niche"?

Answer 45

We have high brain power to learn, and we are the smallest age in millions. Learning requires sophisticated skill

Question 46

When does social learning arise?

Answer 46

When benefits exceed the costs of learning

Question 47

What does social behaviour produce?

Answer 47

behavioural or cultural traditions

Question 48

Cumulative cultural evolution is a...?

Answer 48

critical aspect of human adaptation