276 Self and the Phenomenon of Life
b2726 Self and the Phenomenon of Life: A Biologist Examines Life from Molecules to Humanity “9x6”Human culture originates from the ability of the brain to manip-
ulate symbols, defined as an object, an act or an idea capable of repre-
senting something other than itself, usually of an abstract and complex
nature, as exemplified by language. A prerequisite for symbol formation
is the ability to perform abstract thinking. Because of this abstraction,
a symbol can carry an enormous amount of information. Think of the
history of a nation rolled into a simple flag, or consumer expectation
embedded in a company logo.
The relationship between gene and culture is part of the age-old
debate of nature versus nurture. The truth is that they have parallel yet
interactive developments. Culture has certain contingent determinants
that impart local flavor, but culture also has a genetic basis that confers
certain universalities. Thus, we all have an inborn sense of rhythm and
melody, but these alone do not predict whether the music of a people
will be the enlivened contrapuntal melody of the Baroque period, or the
tranquil mood of an Indian morning raga.
Culture affects genome in a way more than most of us realize. One
striking illustration of gene-culture co-evolution is the interaction of
cattle domestication and the gene for lactose digestion called lactase.
Lactose is the sugar component of milk. All newborn mammals have the
ability to digest lactose because they have lactase in the intestine, but the
enzyme level declines after weaning. Adult humans who do not have this
enzyme are lactose intolerant — they have bad reactions to fresh cow
milk and may have symptoms of abdominal cramps and diarrhea. Those
adults who carry the lactase gene can produce the enzyme and have no
problem drinking milk. It is interesting to note that the appearance of
the adult lactase gene correlates with the domestication of cattle, which
occurred six thousand years ago. Further, the gene is now most prevalent
in the Scandinavian countries where over 90% of the population are pos-
itive. It happens that, in addition to being an energy source, lactose aids
in calcium absorption, a process needed for maintaining bone integrity,
important in the northern part of the world where sunlight exposure is
deficient (sunlight stimulates the formation of active vitamin D in the