268 Self and the Phenomenon of Life
b2726 Self and the Phenomenon of Life: A Biologist Examines Life from Molecules to Humanity “9x6”to help out others in need even if they are not genetically related. This
inborn conscience is engrained in the genome of humankind, “sculpted”
by millions of years of relentless natural selection. The reason is, a spe-
cies whose members help one another stands a better chance of survival,
and therefore is favored by evolution. Human conscience constitutes a
strong social cohesive force.
12.6.2 Basic physiologic needs
Smell and touch are primitive factors involved in social bonding. Odor
can evoke a strong emotional response, and a person may feel attracted
to, or repulsed by, another because of body odor, sometimes even below
the threshold of awareness. Odor preferences may be inborn or learned
at a young age. For example, a tempestuous toddler can easily be calmed
down by the familiar smell of a security blanket. People may become
homesick if they miss the unique odor of their old houses. And think of
the billions of dollars men and women spend each year on perfumes.
Touch is another socially relevant stimulus. Hugging, caressing, kissing,
and intercourse are different forms of tactile sensory satisfaction animals
and humans seek. For a newborn, the texture and warmth of a mother’s
breasts provide one of the earliest bonds between mother and child. The
softness of a stuffed animal provides security to most infants.^12
12.6.3 Pro-social hormones
The effects of estrogen and androgen on sexual attraction and virility
are well known. Among other hormones, two stand out as particularly
relevant to social bonding: oxytocin and vasopressin, both small peptides
endogenous to the brain.^13 In the nervous system, oxytocin and vaso-
pressin have potent neuro-modulatory effects through activation of the
dopamine motivation/reward system, in particular the nucleus accum-
bens and ventral pallidum of the forebrain. (See Chapter 9: Self and
Emotion for the brain structures.) Strong effects of these substances on