The Expanded Self: Society as Self 269“9x6” b2726 Self and the Phenomenon of Life: A Biologist Examines Life from Molecules to Humanitypair bonding have been demonstrated in field rodents.^14 For example,
prairie voles exhibit a monogamous social structure while closely related
meadow voles are polygamous. Pair bonding behavior in prairie voles
is correlated with a high density of vasopressin receptors in the ventral
pallidum, and of oxytocin receptors in the nucleus accumbens. Bond-
ing in these animals is lost when these receptors are blocked.^15 On the
contrary, male meadow voles, which normally are promiscuous and do
not form male-female bonds, can be induced to express pair bonding by
introducing vasopressin receptors to the ventral pallidum.^16 In another
experiment, female mice whose oxytocin receptor gene has been inacti-
vated show a deficit in maternal behavior.^17
Pro-social behaviors of oxytocin in humans are well recognized.
After childbirth, oxytocin motivates the mother to nuzzle and protect
the newborn, forging a strong mother-child relationship. In both sexes,
oxytocin induces care, warmth, tenderness, attachment, cooperation,
trust, generosity, and empathy.^18 However, when humans are divided
into groups, it was found that oxytocin motivates in-group conformity
and favoritism but promotes out-group derogation, implying hormonal
influence on ethnic prejudice and xenophobia.^19 Another example of
neuro-hormonal influence on social behavior is seen in desert locusts.
These insects live a solitary life when population density is low. But
when the population reaches a critical point, they start to aggregate and
swarm. The switch from initial mutual repulsion to strong attraction is
triggered by the neurotransmitter serotonin.^20
12.6.4 Early life experience
Humans and other animals are attached to things they experienced in
early life, sometimes within a critical period. Perhaps the most dramatic
example is the case of “imprinting” demonstrated by Konrad Lorenz.
As goslings are attached to the first moving object they see after hatch-
ing, Lorenz was able to show that they preferred to follow him instead
of their natural mother. Humans learn their native tongue easily and