Just finished reading three books authored by Robin Dunbar.  How many friends do you need? and the science of love and betrayal are popularising insights from developmental psychology.  The first explores the limits to sociality and the drive to social interaction.  This is a theme in the other books reviewed here and a topic on which Dunbar is an authority.

The second book exposes the drive to mate & bond in social groups.  I find a number of theories and ideas interesting: 

• Romantic love can be “simply” ranked on the basis of intimacy, commitment and passion. This goes against my earlier attempts (at the tender age of 16) to demonstrate how romantic love exists as a system of socio-cultural oppression 🙂
• The grandmother hypothesis links evolutionary to social pressures. It is used as an explanation of early female menopause (females take themselves out of the reproductive cycle to care for the offspring of their daughters).
• Choosing a mate is typically the outcome of a triadic interaction (involving potential alternative mates for the chooser).
  • Studies of courtship indicate females give ambivalent signals to potential mates in order to optimise their choice pool of potential mates.
  • Females prefer taller males, while males shorter females, countering hight selection biases in the DNA of offspring.
  • Relative neoteny preference is universal: studies indicate that women whose predicted age was less than their actual age were considered more attractive.
• Grooming in primates (massage in modern humans?) is pre-dominantly a bonding exercise that increases oxytocin.
  • Cortisol (stress hormone) in humans is inversely related to partner intimacy.
  • Dopamin (affecting attention levels and the smooth execution of tasks) and endorphin (pain control) are associated to grooming and (obviously the nurturing) interaction with lovers.
  • Suckling is an anti-stress strategy.
• Laughter derives from play invitation behaviour – guess related to tickling then 🙂
• Kissing is about testing the genetic compatibility and health of potential partners. Nothing to do with the art of kissing then…
• Native Indian war chiefs in the 19th c. were orphans at the bottom of the social ladder seeking tribal recognition and a chance to a mate. This appears similar in the recruitment for many current revolts/uprisings masked under religious fanaticism and underpinned by a population explosion.
• More symmetrical people (typically judged as better looking) produce children with higher IQ.
• Women with waist to hip ratio close to 0.7 have children with higher IQ.
• Female primates copy each other’s mating preferences.  A Matthew effect in mating!
  • Eye-shadow in female make-up imitate the effects of ovulation on the eyes.
  • Wearing high heels might be a signal of fitness, impossible if legs are not symmetrical.
• Five key traits in creating friendships: sense of humour similarity; same hobbies; same values; same education/intelligence; proximity of birth place.  Some appear to me co-dependent on antecedent variables and collectively indicate a strong homophily effect.
• The cost of falling in love is the loss of two close friends. Given that our total number of close friends is fixed, this explains the anecdotal hostility a new partner receives among their partner’s friends. They know their friend will have less time for them and is likely loose the strong tie to some of them.  A friendship threat indeed!
• Exaggerating a partner’s qualities at the early phase of courtship predicts greater satisfaction with them in the long term.  I call this the pedestal syndrome, the higher the pedestal, the longer it takes to be able to achieve a realistic assessment 🙂
• Availability of alternative partners: The sex ratio in the workplace is a good predictor of divorce rates!
• Pairbonding: In primates, a shorter second to a fourth finger (D2:D4 ratio) indicates polygamous behaviour.
  • Monogamy in homo sapiens might be an evolutionary strategy, as females are unable to maintain accurate relational information on the large group size of kin groups.

NEXT SECTION TOMORROW ON THINKING BIG