2. Kin recognition

Question 1

intro to kin recognition

Answer 1

Although not often considered, humans both produce cues to kinship that vary with genetic relatedness and have perceptual abilities to detect these cues in others and assess that relatedness. The potential functions of these abilities are discussed.

Question 2

what is kin recognition?

Answer 2

Kin recognition is an unobservable internal process of assessing genetic relatednes

Question 3

how can kin recognition be inferred?

Answer 3

is inferred by kin discrimination, the observable differential treatment of conspecifics based on cues that vary with relatedness

Question 4

e.g.’s of kin recognition in animals

Answer 4

• Lots of species have a way of regulating their behaviour in order to enhance their own inclusive fitness

Some animals remarkably good at this 

Japanese quails (Bateson, 1982)

Ostriches and eggs (Bertram, 1977)

Honey bees (Page and Erikson, 1984)

Question 5

what does kin selection aim to actually achieve?

Answer 5

better inclusive fitness

Question 6

kin recognition in Japanese Quails

Answer 6

• Japanese quails and mate choice (Bateson, 1982)- if given a sibling, 1st cousin or unrelated bird that they’ve never met before- more likely to preferentially mate with 1st cousin- optimal relatedness in breeding pairs- defo treated differently if related.

Question 7

kin recognition in ostriches

Answer 7

• Ostriches and eggs (Bertram, 1977)
o Engage on co-operative nesting
o Sits on eggs of other females
o If not enough room kicks out eggs of other females rather than their own

Question 8

kin recognition in honey bees

Answer 8

• Honey bees and larvae (Page and Erikson, 1984)

o More likely to feed larvae to turn into queens pick ones more related to themselves

Question 9

mammals and kin recognition

Answer 9

• Numerous examples of mammals preferring to socialise with, avoid conflict with relatives

Question 10

what two broad things can we use to know relatedness

Answer 10

Social cues

and phenotype matching

Question 11

what two social cues are there?

Answer 11

proximity-e.g. nearest thing when born and association- spending lots of time together

Question 12

what did hamilton posit in terms of phenotype matching/

Answer 12

Hamilton posited that genes should affect ‘(1) some perceptible feature of the organism, (2) the perception of that feature, and (3) the social response consequent upon what was perceived’ (1964).

Question 13

what does an understanding of kin phenotype recognition consist of nowadays?

Answer 13

an understanding of kin recognition involves three components: the production of unique phenotypic cues, or ‘labels’, the perception of these labels and their degree of correspondence with a ‘recognition template’ (these components are the mechanism of recognition), and the action taken by an animal as a function of the similarity between its template and an encountered phenotype (Mateo 2003, 2004)

Question 14

what could lead us to believe that we recognise kin through facial features?

Answer 14

Humans have entire visual areas devoted to facial recognition thus would serve that one way we recognise kin is through facial features.

Question 15

evidence for genetic relatedness in facial features

Answer 15

Mothers can recognize photographs of their infants within 33 h of birth, and strangers can match photographs of mothers to their infants, suggesting a physical resemblance among kin (Porter et al. 1984) – thus strangers perceptions are based on phenotype matching.
People can also match faces of siblings to whom they are not related (Maloney & Dal Martello 2006) and assess the relatedness of pairs of close and distant kin (e.g., grandparents and grandchildren, aunts and nephews/nieces; Kaminski et al. 2009).
Thus, there appear to be cues to genetic relatedness in facial features.

Question 16

what examples are there suggesting there is a visual modality to kin recognition?

Answer 16

• genetic relatedness cues in faces
• we trust more faces that are our own
• more attracted to faces that look genetically different

all these suggest that there is something we can tell about genetics from the face

Question 17

evidence that we trust self-familiar faces more

Answer 17

o	DeBruine (2002)
o	Used facial morphing to create self-similarity in a stranger’s face- calculate 2D structure of base face and participant and then morph colour info into morph of the two people uses hair and clothes of the base face. 
o	Participants co-operate with their own self-morph and some others’ self-morph. Look at how much someone co-operates with themselves controlling for how much the other person also wants to co-operate with them (some people may just generally look nicer and more trust worthy)
o	Play a trust game- and found that they are sig more likely to trust self-morphs than non-self morphs. If look at fairness (ie. when on other side of trust game and if you then cheat or give someone a fair amount) there is no difference to self and non-self so maybe people are just generally giving especially middle class uni students.

• Krupp et al., 2012
o Public goods game- everyone puts money into pot- that pot is then multiplied and divided between players- best way to play is to cheat it and not put money in but get the money out (free-riding)
o People were placed into groups of 4 where there were 2 co-operators and a free rider- got to see pics of who playing with- either 3 strangers, 2 strangers 1 self-resembling or 2 self-resembling, 1 stranger.
o The more self-resembling faces within ‘group’ the greater public goods contributions- the more people are trusting- trust own relatives more
o No change in costly punishment (e.g. can pay a pound and find out who the free rider is to take money off of them)

Question 18

menstruation and facial preference for own looking faces study

Answer 18

• DeBruine, Jones & Perrett (2005)
o Menstrual cycle study- looking at how preference for self and others changes across the menstrual cycle
o Young and female, mature and female, young and male, mature and male
o Luteal phase (middle of the second half of menstrual cycle), follicular (2nd week of menstrual cycle) can become pregnant in the follicular stage but not in luteal phase. In luteal phase there is a high rise in progesterone waiting for a fertilised ovum.
o Follicular phase- these is no self-similarity preference nor aversion
o In luteal phase- preference for self-similar faces and this is particularly strong for female faces (mostly straight women).
o Why might spike in progesterone lead to preference for self-similar faces- progesterone goes up in luteal phase progesterone only goes up more when pregnant- preference for female kin network when hormones are telling you that you might be pregnant. Body is hormonally half way there when in luteal stage- female kin extremely important when pregnant.

Question 19

what is a potential issue with studies that show preference to self-familiar faces?

Answer 19

Don’t have mirrors how can you know what you look like if you don’t have a mirror? People have argued that all you need is a still dark pool and this is probably not that true- mechanism must build on something else…

Question 20

what do experimenters who manipulate faces to look like self hope they are manipulating? but what is still the issue with this

Answer 20

Can build a model of self-similarity without a mirror by basing on a template of those related to you
Use kin to form image of self-similarity recognise kin based on self-similar faces which leads back to using kin to form image of self-similarity—is arguably very circular. This doesn’t work if this is your only way of detecting kin and only way to correctly regulate behaviour towards kin as need something else to correctly build template in the first place.

Question 21

if need to know kin before kin recognition template is created then what does this suggest? but who argues against this and why?

Answer 21

So is it all about familiarity?
DeBruine argues this is not true- because same study with famous and non-famous faces i.e. are you more likely to trust someone you don’t know but who looks very like a celebrity than you are to trust someone you don’t know and who looks like nobody you know. Morphs of highly familiar but not related individuals didn’t produce the same behaviours. But haven’t acc met many of these celebrities maybe you need real interaction and not just visual association

Question 22

what brain imagining research also supports DeBruine’s research on kin recognition in faces?

Answer 22

Detection of resemblance in children’s faces activates the left frontal cortex in men, but not women, suggesting possible decision-making processes involved in assessment of paternity and possible investment (Platek et al. 2004). Kin faces (versus unknown faces) activate regions involved in self-face recognition (e.g., anterior cingulate gyrus and medial frontal gyrus), whereas kin versus friend faces activate posterior cingulate and cuneus, again suggesting a need to process for identification (Platek & Kemp 2009). Multiple mechanisms for discriminating kin faces may have been favored by selection due to the need for fast and accurate recognition.

but still there must be an initial mechanism to know kin to begin.

Question 23

what is kin recognition by smell called?

Answer 23

Olfactory cues

Question 24

olfactory cues in animals

Answer 24

Olfactory cues are known to covary with genetic relatedness in a variety of taxa (e.g. birds: Coffin et al., 2011; mammals Halpin 1986)

Question 25

olfactory cues in humans evidence?

Answer 25

• Infants rapidly recognise the mother’s scent when they are born- partly because they have been in utero swallowing and breathing amniotic fluid which is itself carrying chemical compounds to do with mother’s diet so already exposed to mothers scent- newborn babies can orient to mothers scent.
• Parents can recognise own offspring by scent-
o Porter and Moore (1981)
o Children slept in t shirts for 3 nights (unscented scent and detergent)
o Parents smelled the t shirts
o 19/14 siblings recognised each other’s smell
o 17/18 tests on mothers achieved recognition
o 8/9 recognised both their children
o Study 2- 16/18 parents could recognise and discriminate between their offspring.

Question 26

argument against olfactory cues in humans?

Answer 26

argued that it may just be familiarity?

o Hold and Schleidt (1977)- found that partners recognised each other’s smell just because become familiar with that smell
o So partly we just learn smells and is a by-product of a social cue.

Question 27

what is evidence that odors can actually be cues to kin in humans?

Answer 27

Fathers, grandmothers, and aunts can also identify their related infant with little prior contact (Porter et al. 1986- so suggests that it is smell to an extent- suggesting a shared genetic component in the odors of family members.

Odor-based recognition of kin can go beyond simple familiarity with individual’s cues, however. People can match the odors of mothers and their children, despite being unrelated to the odor donors, indicating discrimination based on phenotype matching. That husbands and wives cannot be reliably matched by odor indicates that odor recognition is mediated through shared genes rather than a shared environment (Porter et al. 1985)

Accordingly, extended periods of separation do not diminish the ability to recognize kin (Porter et al. 1986)

Question 28

what is evidence that odors can actually be cues to kin in animals?

Answer 28

an habituation–discrimination study using rats shows that human odors covary directly with genetic relatedness, with close kin (e.g., mother, sister) having more similar odors than distant kin (e.g., aunt, niece, grandmother), which in turn have more similar odors than non-kin (Ables et al. 2007).

Question 29

what would provide additional information to the fact that odors may be cues to kin relatedness?

Answer 29

that odors influence human social interactions

evidence in parents and in mate choice

Question 30

evidence of odors influencing social interactions for parents

Answer 30

• mothers who are better able to recognize their infant’s odor also report better nursing experiences and positive mothering attitudes (Fleming et al. 1995)
• Fathers have greater attachment and show more affection toward offspring they can identify by odor. In contrast, mothers use more punishment with offspring whose odors they cannot identify and use less punishment with children with odors they rate as pleasant (Dubas et al. 2009).

Question 31

evidence of odors influencing social interactions for mate choice

Answer 31

human leukocyte antigen (HLA) influences odor preferences (Jacob et al. 2002), suggesting that odors may mediate mate choice so individuals choose partners via smell who have different genetic makeup. This has functional consequences, because couples with dissimilar HLAs have fewer miscarriages than those with similar HLAs (Ober 1999; cf. Hedrick & Black 1997).

may play a role in mate choice to increase heterogeneity, especially in immune functioning, and to minimize inbreeding (e.g., Penn & Potts 1998), and thus genetic diversity regarding the immune function of offspring would be increased by disassortative mating.

Question 32

intro to social/ proximal cues to kin relatedness

Answer 32

But perhaps it is childhood familiarity/ association that is driving everything and the building of a template that drives everything else

Question 33

what leads us to believe that social/ proximal cues play a large role?

Answer 33

Use example of step-siblings versus uncles- clearly something more is driving kin and a sense that a step brother is closer.

Question 34

what is a phenomenon seen in the animal kingdom upon birth but not in humans?

Answer 34

Phenomenon in animal kingdom but not humans is imprinting- where a young individual imprints on another individual as their care giver- simple mechanism you hatch and the first individual you see almost has to be care giver and as long as you maintain proximity to this care giver you will be safe until old enough. Nice simple mechanism produces raft of useful behaviours. E.g. goose will imprint on humans. A simple mechanism allows newborns to determine who is related to them

Question 35

what have arguments about social cues to kin relatedness argued?

Answer 35

that these systems may have emerged as less of a result of needing to know who behave more altruistically to but instead as a method to avoid incest.

Question 36

incest avoidance in chimps

Answer 36

• Walker et al (2017) Chimpanzee dyad relatedness
o Live in multi-male multi-female groups males tend to stay put in groups whilst females migrate
o Get different degrees of relatedness within a troupe- it is not just alpha males giving breeding thus can get variance between the dyads in terms of how related they are to each other
o If compared all the breeding dyads and compare them to every other possible dyad in the group- you see that the breeding dyads tend to cluster in the lower half of the relatedness spectrum whereas general possible dyads are quite spread across relatedness.
o Chimps are less likely to breed with an individual that is closely related to them.

Question 37

who proposed the system of incest avoidance in humans and what is it called?

Answer 37

Westermarck Effect

Westermarck, 1891

Question 38

what observations have been used as evidence to support the Westermarck effect?

Answer 38

Israeli kibbutz system, and the Chinese Shim-pua marriage customs,

Question 39

explain findings of chinese shim-pua marriage and the westermarck effect

Answer 39

o Girls are sent to the household of their husband/ future household- girl is going to do all breeding for this family so cost of raising goes to the family who will get benefit along patriline.
o Problem was however that husbands and wives were growing up together and were very unlikely to actually want to marry one another
o High separation rates
o Low fertility didn’t want to mate with one another
o Argued they felt like siblings

Question 40

explain findings of kibbutzim marriage and the westermarck effect

Answer 40

kibbutzim= communal farm

o Children are raised together in communal nursery houses and adults rotate looking after.
o Children from kibbutzim’s are very unlikely to be sexually attracted to someone in their own cohort

Question 41

what other evidence supports the Westermarck effect?

Answer 41

• global incest taboos
• empirical evidence- (Reuinited siblings Bevc and Silverman, 2000)
• empirical evidence- co-residence and 3rd party disgust (Liberman et al., 2003)

Question 42

what data further explored the Kibbutzim?

Answer 42

o Lieberman and Lobel (2012)- Kibbutzim measured co-residence duration with opposite sex peers, sexual attraction to opposite sex peers and moral attitudes relating to peer sexual behaviour amongst third parties- the effects of growing up amongst peers on moral attitudes to other people was entirely mediated by own sense of personal disgust to the idea of sleeping with own sibling/ peer.

Question 43

what did Freud argue about incest?

Answer 43

o Freud argued that we had to learn not to sleep with our close relatives and that this was something that we would have a dilemma about

Question 44

what goes against Freud’s ideas on incest?

Answer 44

o Westermarck made opposite observation

Question 45

global incest taboos and Westermarck effect

Answer 45

• if you look globally there are rules about who you can marry
  o E.g. uk can marry first cousin but not in many parts of the US
  o Yanomamo practice bilateral cross-cousin marriage (mothers brothers child or fathers sisters child) but not first parallel cousin (fathers brothers child or mothers sisters child)
  o European royalty used to jump through a lot of hoops to work out who was related or not
  o Lots or rules about marriage but very few ritualised rules about marrying parents or siblings- Westermarck argues that this is because this hardly ever crops up people don’t want to mate with these individuals. Grow up together highly exposed to each other which triggers kinship which makes us find them sexually aversive and stops us wanting to marry/ be with them

Question 46

where are example of when incest can occur historically?

Answer 46

o Only examples where do see incest tend to see child rearing practices that interfere with the Westermarck effect e.g. Pharos to the throne being raised separately to their sister then in adulthood doesn’t mind as much.

Question 47

re-united siblings and the Westermarck effect

Answer 47

Bevc & Silverman (2000)- highly likely to feel sexual attraction towards each other it is a thing people are given counselling about when seeking lost relatives.

Question 48

co-residence empirical evidence and the Westermarck effect

Answer 48

o Co-residence and 3rd party disgust: Lieberman et al (2003); Fessler and Navarette (2004)-plenty of evidence shows that living with a opposite sex sibling predicts your disgust reaction to the idea of incest being engaged in by third parties.

Question 49

what is the overarching idea of the westermarck effect?

Answer 49

o You have early exposure that makes you feel sexual aversion to a person and from this is constructed more abstract moral ideas about how should behave

Argument is that early exposure is crucial to forming this kinship between individuals and if we go back to the first issue of half-brothers not killing each other as much as uncles and nephews potentially because half- brothers have grown up in same environment and feel psychologically as though they are closer kin.

Question 50

What is the Westermarck effect a psychological mechanism for?

Answer 50

Essentially is a psychological mechanism designed to identify kin who you co-operate with but don’t sleep with. Bit is slightly misfiring when you have half siblings versus full siblings because the only cues you have to go on are the same regardless of whether kin is full or half.

Question 51

what cues do we have to kin-relatedness overall

Answer 51

phenotypic- facial and olfactory

social- Westermarck effect

Question 52

is clear that the Westermarck effect is present but what could be the cues within this?

Answer 52

• Co-residence?
• Co-socialisation?
• Observation of maternal care?

Question 53

what is the main question in terms of the Westermarck effect for kinship?

Answer 53

Westermarck’s hypothesis is clearly valid in sexual attraction but can it regulate altruism also..?

Question 54

What do organisms require in order to regulate behaviour conditionally in response to different degrees of kinship?

Answer 54

To regulate behaviour conditionally in response to different degrees of kinship, organisms require mechanisms to discriminate genetic relatedness.

Question 55

study on MPA and what is MPA? What did the study predict?

Answer 55

Liberman et al., 2007

Argues that as well as co-residence, maternal perinatal association (MPA) is highly important for understanding kin and can be used as an anchor point for sibling detection. Ancestrally, if an individual observed an infant in a durable, perinatal association with the individual’s mother, then it was highly probable that that the infant was the individual’s sibling. They propose that sibling detection includes a monitoring sub-system specialised for registering MPA.
Although MPA is the single most informative cue they argue, it can not be used (for example) by younger siblings as they were not alive at the time of an older siblings birth and nursing. Thus they argue that when MPA is not present the kinship estimator should fall back on co-residence

Question 56

What did the study on MPA find?

Answer 56

• When the MPA cue is present—which can only be true for olders detecting younger siblings—levels of altruism and sexual aversion are high.
• When MPA, coresidence and beliefs about sibling kinship were all entered into a multiple regression, MPA was the only variable to independently predict variance in altruism towards younger siblings

When MPA absent:
• Coresidence duration significantly predicts ltruistic motivations and, separately, opposition to first and third person incest

Question 57

what is the issue with the MPA study?

Answer 57

almost no variance in some of their items without variance can not statistically model that variance and can’t come up with causal models as no variance to work with in the first place
• Either tap into this question in a more subtle way which is less open to response bias e.g. electrophysiology OR stop messing about with undergraduates and find people who are actually in this situs e.g. in reuinited siblings and see if its modulated by things like if they were related- try and look at the real world behaviour of what they are trying to explain…i.e. see if their model modulates these also.
• doesn’t provide an explanation as to how it happens

Question 58

What study didn’t support MPA?

What does this suggest?

Answer 58

BUT….Pollett (2007)
• looked at sibling altruism in the UK
• actually looked at self-reported real altruism between real siblings in the UK
• less altruism towards half-sibs than full regardless of
o co-residence
o MPA
o Proximity
o Gender
o Age gap
• People in adulthood less likely to phone, spend time, lend money to half siblings than half siblings
• In terms of behavioural investment for adults seems to be a regulation that full siblings get more of it than half

So maybe conscious knowledge does play a part/ alternatively could have less in common with a half sibling thus maybe less overlapping interest and desire to talk to one another as less genetic compatibility i.e. same things that regulate normal prosocial behaviour and friendships.
If MPA is this magic bullet that goes ‘yes this is my sibling’ then we shouldn’t see this altruism effect of altruism on half and full siblings.

Question 59

Conclusion

Answer 59

Overall, seems that a wide number of resources may be used in order to recognise kin, and perhaps that these originate not from a need to know our own kin but to actively avoid committing incest with our direct kin.