Download SR 52(11) 30-32

FEATURE ARTICLE
ARATI ARVIND KAREKATTE
Does it have to do with our surroundings, the way we
are nurtured
urtured or does everything boil down to our genes?
O
UR generation was raised on a staple
diet of “Behave yourself”, which, in
short, expected us to be respectful, polite,
hardworking and so on. If not, the rod
was not spared.
‘Spare the rod and spoil the child’
was a household mantra; a teacher was
always depicted with a cane in hand
and parents dare not complain about
the teacher. Did it produce a bunch of
stereotypes at home/school? Hardly, as
siblings we were as different as chalk and
cheese and at school there were motley
crowds in all shades of mischief and
menace.
Why so? A difficult question
to answer when it comes to human
behavior. Why do we behave the way
we do – researchers try to explain
this in contrasting terms – Nature (an
individual’s innate qualities) and Nurture
(an individual’s personal experiences).
In simple terms, biological factors
and environment come together to shape
an individual’s behavior. Both play vital
roles; the former capture the evolutionary
responses of prior populations to select
behavior. Environmental flexibility gives
the opportunity to adjust to changes
during their own lifetime and learning
SCIENCE REPORTER, NOVEMBER 2015
30
Nature vs
Nurture in
Behavior
from this gives tools to respond to local
conditions.
Much of our behavior is learnt after
birth. We are initially equipped with
FEATURE ARTICLE
We exist in an environment, no
gene functions in a vacuum. It
is indeed very fascinating to
learn about the subtle interaction
between Nature and Nurture that
so profoundly affects our lives
and makes each of us – even
identical twins – for what we are
as unique individuals.
Cartoon depicting moods in
humans
some instinctive behavior but our brains
are also wired to acquire new skills in
response to the special needs under
unique conditions. We have successive
phases of growth, each with a distinct set
of physical and behavioral features.
Let us start at the very beginning.
An infant needs no training to suck at
a nipple; sucking is an innate instinct
the infant is born with. Now, you play
a tune and one second later feed him
some sweetened water. After a dozen
repetitions of this, the infant associates
the tune with receiving the sweetened
water and will make sucking movements
to the tune even though no sugar water
is delivered. The infant has learnt to
maintain a sequential relation to create an
association between two stimuli.
Next, repeat the experiment in such a
way that after the tune is played the infant
is required to turn his head to the right to
receive his reward of sweet water. After
a few repetitions the infant learns the
relation between the response of turning
his head and the following receipt of his
reward. So this is the ‘Look, Listen and
Learn’ stage for the infant.
Learning is, therefore, any relatively
permanent change in behavior resulting
from past experience. Rewards such
as praise and approval from parents/
teachers are positive supporters of specific
learned behaviors while punishment
decreases the likelihood of repeating such
behaviors. This is a guiding principle
in explaining the changing behavior
of children during the course of their
development.
As the child grows the brain is
gaining fast in size and he is exposed to
a myriad of stimuli; my three-year-old
grandson once told me “don’t eat mentos,
daadi”. “Why,” I asked. “Lights are not
coming on.” All this courtesy: ‘Dimag ki
batti jalaa de’, a television commercial.
The child has gone one step ahead here
– he has tested what he had observed on
television to see if it is ‘right’ or ‘wrong’.
One more stepping stone indeed!
Piaget’s (1896-1980) theory rests on
the fundamental notion that the child
develops through stages until he arrives at
a stage of logical thinking that resembles
that of an adult.
As adults we describe behavior in
terms of our temperament, attitudes,
personality, character and so on. How
does ‘Nature vs Nurture’ shape all these?
Temperament: Look at the illustration
showing different faces. Each face depicts
a mood – happy, sad, angry, cheerful, shy
and so on; we call them temperaments.
Temperament refers to a set of innate
or inborn traits that display a child’s
approach to the world.
Psychologists conclude that people
can be categorized into four basic types of
temperament: cheerful, irritable, sad and
indifferent. Since it is naturally occurring,
temperament cannot be taught or learnt
but, despite this fact, it can be nurtured
as one grows. Parents have an important
role in nurturing the temperament of their
child from infancy.
Studying one’s own temperament
helps establish personal weaknesses
and strengths. Studying other peoples’
temperaments allows individuals to
adapt their communication skills to
others. Understanding temperament
equips people to successfully handle
interpersonal relationships.
Attitude: I happened to witness an
incident such as above – the young girl
upon slipping over a banana peel corrects
her instinctive ‘amma’ to ‘ouch’ for the
31
Development of attitudes in
humans
benefit of onlookers. Obviously, for
her ‘ouch’ is a smart way of expression.
Attitudes are a complex mental state
involving beliefs and feelings and values
and can change depending on their
emotions or whatever situation they are
in. The stronger the attitude the more
likely it should affect behavior. It is a
positive attitude towards life that makes
us winners.
Personality: Personality is what arises
within the individual; the personality
is usually what that person is, which
can’t really change, unlike attitudes.
Personality is a set of qualities that make
a person distinct from another and is
acquired on top of the temperament.
Personality is also developed over a long
period of time and is affected by factors
like socialization, education and different
pressures in life.
Character: Character is defined as a
component of personality that may
be shaped by both biological and
environmental factors; it is the measure
of ethical and moral trappings and
reasoning. Moral values refer to a set
of principles that guide an individual
on how to evaluate right versus wrong.
Joint research by Paul Bloom and Karen
Wynn of Yale’s Infant Cognition Center
has pointed out that, even six-monthold infants have what Bloom calls “naive
morality”. Thus, character may be proven
to be more like temperament than like
personality. In short, personality is: who
we are and what we do when everybody
is watching and character is who we
are and what we do when nobody is
watching.
The differences between personality,
character and temperament are that
personality and character are defined
SCIENCE REPORTER, NOVEMBER 2015
FEATURE ARTICLE
as with both being dependent on
the combination of biological factors
and
environmental
factors
while
temperament is defined as present at birth
and consistent throughout life despite
environmental factors, which cannot
change but can only shape, or mold, the
expression of temperament.
What are these biological factors? In
1869, Francis Galton published the first
empirical work on human behavioral
genetics, Hereditary Genius stating that
“a man’s natural abilities are derived
by inheritance, under exactly the
same limitations as are the form and
physical features of the whole organic
world”. Though the book had several
overstatements, it paved the way for
revealing that there are indeed genetic
influences on human behavior.
The role of genes can be baffling,
for example, children share half of their
alleles with each parent; if any parenting
style such as aggressive parenting leads
to aggressive child characteristics, then is
it genes or parenting?
Why do we behave the way we do
– researchers try to explain this
in contrasting terms – Nature (an
individual’s innate qualities) and
Nurture (an individual’s personal
experiences).
SCIENCE REPORTER, NOVEMBER 2015
How do we then
search for genes responsible
for our behavior? To
disentangle genetics from
environmental influences,
researchers undertake
a.
Twin
adoption
study where
adoption
disentangles the genetic
relatedness of the twins
(either 50% or 100%) from
their family environments.
b. Classic twin study
contrasts the differences
between
identical
and
fraternal twins within a family compared
to differences observed between families.
c. Extended twin study which adds
additional family members, increasing
power and allowing new genetic and
environmental relationships.
d. Children of twins design holds
maternal genetic contributions equal
across children with paternal genetics and
family environments.
e. Virtual twins design - unrelated
children adopted into a family who are
very close or identical in age to biological
children or other adopted children in the
family.
Many such major studies are
going on in diverse fields such as aging,
substance abuse, cognitive abilities, BMI,
personality, values and so on.
Therefore, genes and the environment
are not to be considered as adversaries.
They are two forces that interact and they
do so to mold many of our characteristics.
Such traits are multifactorial, i.e.,
influenced
by
both
genes
and
environment. The genetic component can
be a single gene known as a Mendelian
trait or many genes (polygenic); the effect
of these multiple genes is often additive
producing a continuum of phenotype
called a quantitative trait. A multifactorial
trait is, therefore, continuously varying
if it is polygenic, exhibiting a range of
phenotypes. Most behavioral traits are
believed to be polygenic.
Consider this: A dimple (single gene)
is present or absent; i.e., the switch is ON
or OFF. But the accompanying smile
(polygenic) has a range of expressions
in its several avatars, as though there is
a rheostat operating internally. Now does
it make sense to you why our happiness,
anger, intelligence, shyness, etc. can
be displayed in continuous hues and
shades?
32
Twin and adoption studies provide
only a first step in analyzing genetic
influences on human behavior. Such
studies identify traits that are likely
to have large genetic components and
that might be good candidates for gene
searches such as the genome-wide scan
for genes that cause or predispose to
certain behavioral traits
Currently, the largest branch of
human behavioral genetics works on
phenotypes such as schizophrenia, bipolar
disorder, and alcoholism. Dean Hamer’s
work on alcoholism is exemplary.
Interactions and contributions of
genes and the environment provide
some of the greatest challenges in human
genetics. Why does one heavy smoker
develop lung cancer while another does
not? How can one time and again overeat,
not gaining an ounce, while another has
to count every morsel?
Because we exist in an environment,
no gene functions in a vacuum. It is indeed
very fascinating to learn about the subtle
interaction between Nature and Nurture
that so profoundly affects our lives and
makes each of us – even identical twins
– for what we are as unique individuals.
By the way, behavioral traits are not
inherently different from other types of
traits; they simply involve the functioning
of the brain rather than other organs.
Dr. Arati Arvind Karekatte retired as Scientific
Officer at TIFR, Mumbai. Earlier she worked at
MRC, Cambridge and at Yale University for her
PhD work and also taught in the Department of
Biotechnology, University of Pune (1994-1998).
She has done her PhD work in Developmental
Genetics, Drosophila melanogaster, under the
guidance of Prof. P. Babu and Prof. Obaid Siddiqui.
Address: 24A, Lantana Gardens, Bavdhan
Pashan-NDA Road, Pune-411021, Maharashtra;
Email: [email protected]