Human%20Mate%20Choice

1
Chapter 4

• Human Mate Choice

2
Mate Selection

• Choosing for
• Genes
• Parenting
• Looking for
• Underlying universals
• Individual preferences

3
Male/Female Pressures

• Females
• Choosier than males
• Higher reproductive costs
• Greater emphasis on child support
• Males
• Somewhat choosy (especially compared to non-human
  primates!)
• Lower reproductive costs
• Greater emphasis on mating
• Interbirth interval

4
Male Parenting Investment

• Can the male improve the females rearing
  success?
• If yes, selection favours males that help rear
• If no, selection favours males that have many
  matings

5
Quality and Quantity

• Quality fewer, higher caliber offspring
• Quantity more, lower caliber offspring
• Sometimes stated that males favour quantity and
  females quantity
• This is an oversimplification to be avoided
• Comes down to differential reproductive success

6
Life-History Factors

• Brain size correlates with life-history factors
  (age of weaning, sexual maturity, gestation
  length, longevity)
• Species with big brains tend to stretch out
  life-history factors

7
Brains

• Human
• 1.4 kg brain, 65 kg body
• 0.0215 brain/body
• Monkey
• 0.1 kg brain, 7 kg body
• 0.0143 brain/body
• Baboon
• 0.14 kg brain, 30 kg body
• 0.0047 brain/body

8
Gestation Length

• Homo sapiens, average brain capacity of 1350 cc
• Comparison to other primates
• Humans should go 21 months, not only 9
• Humans have a years worth of growth to catch
  up on when born

9
Brain Size

• Newborn apes brain about 200 cc, roughly half
  that of an adults
• Newborn humans brain about 450 cc, roughly a
  third the size of an adults
• Both ape and human brains reach adult size early
  in life, but apes brains only have to double,
  not triple in size
• Brain of 675 cc would make human head to large to
  birth

10
Birthing Complications

• Maternal and infant survival
• Head size vs. pelvis
• Birth vs. bipedal locomotion
• Menopause
• Grandmother hypothesis

11
Ancestral Brain Growth

• Humans departed from apelike growth when adult
  brain passed about 770 cc
• Beyond this, brain would have to more than double
  from birth
• Beginning of helplessness in infants
• Essentially, premature birth
• Homo habilis, 800 cc brain
• Homo erectus, 900 cc brain

12
Developmental Waypoints

• Human childhood prolonged compared to apes
• Slower physical growth
• Tooth eruption later than in apes

Human Chimpanzee 1st molars 6
3 2nd molars 11-12 7 3rd molars
18-20 9
13
Growth Rate and Similarity

• Holly Smith, U of Michigan
• Correlating growth rate with tooth eruption
• Australopithecines growth pattern ape-like
• Early Homo erectus (pre 800 k) growth pattern
  intermediate between apes and modern humans
• Late H. erectus (post 800 k) growth pattern like
  modern humans (and Neanderthals)

14
Parental Certainties

• Female
• Always certain
• Maternal certainty
• Male
• Never certain
• Paternal uncertainty
• Descriptions of childs appearance
• Maternal relatives
• Paternal relatives

15
Certainties
F -- M
16
Cryptic Oestrus

• Concealed ovulation
• No obvious physical indicators of oestrus
• Different from other primates
• Males cant be sure when females are able to
  conceive

17
Why Have Concealed Ovulation?

• Increase paternal certainty
• Also increase chance of pairbonding
• Decrease paternal certainty
• Reduce infanticide
• Allows females to secure more courtship gifts
• Prevent females from avoiding pregnancy

18
Examples of Human Sexually Selected Traits

• Males
• Beards
• Voice
• Upper body
• Height
• Dominance

• Females
• WHR
• Large eyes
• Shiny hair
• Full lips
• Small jaw
• Youthfulness

19
Two Perceptions of Beards

• Negative perceptions of increased recklessness,
  dirtiness, lower mental competence and lower
  intellectual ability, reduced social maturity and
  reduced physical attractiveness
• Positive perceptions such as masculinity,
  strength, intelligence and desirability

20
Reed Blunk (1990)

• Facial hair positively contributes to perceptions
  of social/physical attractiveness, personality,
  composure and competency.

A attractiveness B personality C Competency D
Composure
21
Beards Cheating

• Males lacking dominant, desired appearance may
  use beard
• Hide expressions of emotions, to protect the
  dominant image
• Disguise weak chin, skin damage

22
Male Status is Attractive

• Sadalla et al. (1987)
• Female subjects watched silent video of two men
  interacting in office environment
• More dominant male judged to be of higher status
  and more attractive

23
Male Ambition/Dominance

• Buss (1989)
• Ambition and industriousness valued
• Resource potential

24
Stimuli
Waist-to-Hip Ratio

• Singh (1993)
• Underweight, normal, overweight
• 0.7 to 1.0 WHRs

25
Results Young Subjects
26
Results

• Generally, similar male and female patterns in
  rankings
• Used both WHR and body weight to rank
• Within weight category, subjects systematically
  used WHR to infer all attributes
• Overall, higher ratings for normal weight than
  under- or overweight figures, and for 0.7 WHR
  across weight categories

27
Kate Moss www.eforu.com/gallery/katemoss/pic62.htm
l
Marilyn Monroe www.topnews.in/light/files/Marilyn-
Monroe.jpg
Gong Li www.hicelebs.com/gallery/gong_li/5.html
Venus De milo webpages.ursinus.edu/classics/zzpict
ures/venus_de_milo.jpg
28
Android and Gynoid

• Body shapes
• Testosterone stimulates fat deposits to abdomen
  and inhibits deposits to gluteofemoral regions
• Estrogens inhibit fat deposits in abdomen and
  maximally stimulate deposits to gluteofemoral
  region (and other regions, too)
• Altering sex hormones alters fat distributions
  and body shape
• Age indicator highly different between children
  and elderly
• Honest signals

Image modified from Pioneer Plaques http//www.nd.
edu/jmontgom/ti/GraphicArchive/ Scans/Original20
Files/Pictograph/PioneerPlaque.jpg
29
Female/Male Dimorphism

• Not a simple preference for female WHR0.7
• Cross-cultural WHR data
• Resource availability, re fat storage
• Front vs. side view
• Non-overlapping

Male Female
American blacks 0.84 0.75
American whites 0.82 0.73
Mexican-Americans 0.94 0.84
Moost (Mongolia) 0.85 0.76
30
Symmetry

• Phenotypic depiction of genotype
• Bilateral symmetry
• Fluctuating asymmetry
• Small, random differences
• Genotype and environment
• Immune system
• Sex hormones

31
Age Preferences

• Buss (1989) cross-cultural survey
• Men prefer younger women (average 2.66 years)
• Women prefer older men (average 3.42 years)

32
Reproductive Value and Fertility

• Fertility
• Current probability of successful reproduction
• Reproductive Value
• Age-specific future likelihood of offspring
  production
• Future expected reproductive success
• Average lifetime reproductive success

33
Terms

• Monogamy
• Long-term pairbond with one mate
• Polygamy
• Polygyny male with multiple female mates
• Polyandry female with multiple male mates
• Promiscuity
• Males and females mate with multiple short-term
  partners

34
Savanna Baboons

• Males leave birth troop and join another troop
  nearby
• Males about twice the size of females
• Males not related to other males in troop, so no
  kin selection to ameliorate male-male competition
  for mates

35
Common Chimpanzees

• Males stay with troop theyre born to, females
  leave (dont know why)
• Males maintain kinship with other males
• Leads to male-male alliances and bonds
• Male cooperation reinforced by kin selection
• Hunting, troop protection, female acquisition

36
Bonobo Chimpanzees

• Females also more likely to leave to join another
  troop
• However, very different alliance and bonding
  pattern in bonobos vs. common chimpanzees

37
Size and Structure

• For both chimpanzees and bonobos, males bigger
  than females by about 25
• Close to modern humans
• In chimpanzees, like savanna baboons, males
  dominant over females
• In bonobos, smaller females seem dominant over
  males

38
Humans

• Culture
• Most allow for polygamy
• Monogamy common (obligate or facultative)
• Testis size
• Bigger if polygamous
• Sperm competition
• Sexual size dimorphism
• Greater M/F difference --gt more polygamous

39
Primate Social Organization
female
male
Gibbon
Chimpanzee
monogamous couples
promiscuity strongest bonds between males to
hunt and protect territory
Gorilla
polygamy
Bonobos
promiscuity strongest bonds between females,
but females also bond with males males status
dependent upon mothers
Orangutan
Humans
solitary lives several females within a
males territory
monogamy, polygamy, polyandry, promiscuity
Adapted from de Waal (2006)
40
(In)Fidelity

• Monogamy, polygamy, polyandry, and promiscuity
• Male infidelity
• Additional offspring
• Low investment cost
• Female infidelity
• Access to better genes
• Resources from long-term mate

41
Infidelity

• Women
• Cheat more when reproductively receptive
• Appearance
• Risk taking male for one-night stand, not
  long-term relationship
• A major concern for males
• Genetic altruism

42
Attitudes

• Buss (1989)
• Males value virginity and chastity in women more
  than women do in men
• Buss Schmitt (1993)
• American men rated faithfulness and sexual
  loyalty as most highly valued traits in woman
  for long-term relationship

43
Emotional vs. Sexual Infidelity

• Harris (2000)
• Women more bothered by emotional infidelity
• Across studies, 62-86
• Men more bothered by sexual infidelity
• Across studies, 47-60

44
Children from Previous Relation

• Step-parenting
• Investing resources in non-biological offspring
• Detractor

45
Reality Television
46
History

• Long history (eg. Candid Camera)
• MTVs Real World in 1992
• Very popular
• Final episode of Survivor (2000) 51,000,000
  viewers
• Survivor Palau premiered to 23.66 million
  viewers on Thursday, February 17

www.erzwiss.uni-hamburg.de/ personal/gramlinger/
47
Finding a Mate Shows

• Long-term (e.g., Bachelor(ette)) or short-term
  (e.g., Elimidate) mating strategy
• Resources
• Attractiveness
• Fidelity

gsep.pepperdine.edu/.../ fall2003/reality-tv.htm
48
Long-term Mating Strategy Shows

• More than one episode
• Generally males dont blatantly display resources
• Cast appears classier
• Winner is supposed to be a husband or wife, not a
  fling

http//www.espn.com
49
Short-term Mating Strategy Shows

• Usually a single episode
• Women show more skin
• Men explicitly show resources
• Both sexes often deceive by withholding truth or
  lying

http//www.knws51.com
50
Picking a Long-term Partner (Both Sexes)

• Schmitt Buss (1996)
• Act helpfully, honestly, kindly, sensitively
• Become friends
• Communicate
• Invoke love and show commitment
• Call rivals exploitative, selfish, and insensitive

51
Female Attracting Male (Long-Term)

• Display sexual exclusivity
• Question rivals fidelity

52
Male Attracting Female (Long-Term)

• Display resources
• Demonstrate commitment
• Derogate rivals achievements
• Derogate rivals resource potential
• Suggest rival lacks goals

53
Picking a Short-term Partner

• Buss Schmitt (1993)
• Females maintain higher standards
• Males more likely to accept minimum criteria for
  casual sex
• Males reject women with indications of low sex
  drive, prudishness, and desire for commitment
• High promiscuity favoured for short-term but not
  long-term partner

54
Female Attracting Male (Short-Term)

• Act flirtatious and seductive
• Sexualize appearance
• Make a sexual proposition
• Downplay intelligence
• Have sex
• Call rival sexually unavailable

55
Male Attracting Female (Short-Term)

• Give resources immediately
• Machismo
• Display dominance, confidence, and resources
• Show-off
• Derogate rivals resources

56
Male Success in Bachelorette

• Men often describe themselves as intelligent,
  ambitious, and reference their resources
• Greatest Achievements
• Owning my own home and business. Chris C.
  (Bachelorette 3)
• Graduating from Stanford Business School while
  starting companies along the way. Chris M.
  (Bachelorette 3)

57
Success

• In Bachelorette favoured men are generally
  relatively successful
• Lawyers, business executives, sports agents, etc.
• Bachelors typically extremely successful and/or
  heirs to fortunes
• e.g., Andrew Firestone (Bachelor 3)

http//www.abcactionnews.com/entertainment/stories
/0305/030518bachelor.shtml
58
Success

• In Bachelor, most women are less successful
• Students, service industry
• Bachelorettes are fairly successful, but lower
  status than male counterparts in Bachelor
• e.g., Meredith (Bachelorette 2) was a make-up
  artist
• However, in Bachelorette 4, DeAnna Pappas is real
  estate agent and winning man, Jesse, a
  professional snowboarder

www.ruggedelegantliving.com/sf/a/002338.html
abc.go.com/primetime/bachelorette/index?pnphotos
t109339
59
Age Range

• Bachelorette 3 (25 men, 1 woman)
• Jen, the bachelorette, was 28
• Average of men was 30 (range 25-37)
• Bachelor 6 (26 women, 2 men)
• Byron and Jay, the bachelors, were both 40
• Average age of women was 32 (range 27-39)

60
Attractiveness

• Most women in reality TV are considered average
  or above average in appearance
• This is what men favour (e.g., Buss 1989)
• Male physical attractiveness on reality TV is not
  as consistent
• This is also the pattern predicted by EP

61
Personality

• Some men gain popularity via personality
• Bob (Bachelorette 1), slightly overweight, won
  female fans because of genuineness and sense of
  humour. He became the bachelor for Bachelor 4.
• Adam Mesh (Average Joe 1) was so popular with
  female fans he got his own show. Average Joe
  Adam Returns

www.realitytvworld.com/averagejoe3/
62
(No Transcript)
63
Fidelity and Children

• 9/25 and 12/25 men stated they were loyal,
  trustworthy, or honest in Bachelorette 1 and
  3, respectively
• On Bachelor 2 Aaron was bothered that one of the
  final 3 women (Gwen) had been previously married
  he didnt pick her
• On Average Joe 3 Adam eliminated Brittany when
  she told him she had a 6 year old son, stating it
  would add one more element to the relationship

www.gwengiolia.com
www.wchstv.com/abc/ thebachelor/
community.realitytvworld.com
www.realitytvplanet.com