An emerging area of research called “epigenetics” opens the door to a scientific blending of two worlds that for decades were thought of as totally separate—
that is nature and nurture, or more specifically genetics and the environment.
Epigenetics research looks at how your environment, over time, can affect how your genes work and influence your development, health, and aging.
At the center of this research is the
Epigenetics might also explain variations
epigenome—chemical modifications, or
in lifespan among laboratory mice that are
marks, on our DNA, or in proteins that
genetically identical and seemingly raised
interact with DNA, that tell it what to do,
in the exact same environment. Scientists
where to do it, and when to do it. The marks
theorize that the difference in their
that make up the epigenome are affected
lifespans may result from a disparity in the
by your lifestyle and environment and may
amount of nurturing they received when
change, for example, based on what you eat
very young. The mice with the shorter
and drink, if you smoke, what medicines
lifespan might have been less adept at feed-
you take, and what pollutants you encounter. ing and, therefore, got less of their mother’s Changes in the epigenome can cause
milk, or their mother may have licked them
changes in gene activity. Most epigenetic
less, or they may have slept farther away from
changes are likely harmless, but some could
the center of the litter. Receiving less nurtur-
trigger or exacerbate a disease or condition,
ing may have influenced their epigenetics,
such as your risk for age-related diseases.
marking the genes that control aging.
In some cases, scientists find that these
As epigenetic research moves forward,
epigenetic changes driven by the environ-
scientists hope to answer three key questions:
ment can be inherited by the offspring.
• How do changes in the epigenome trans-
Identical, maternal twins are ideal for
epigenetic research. At birth, twins have
late into long-term differences in health
nearly the same genetic blueprint; however,
and aging?
over time, they may have fewer identical
• Do single events influence the epigenome?
traits. Careful study of these changes may
• If single events can change the epigenome,
help scientists better understand environ-
does the organism’s age (or stage of devel-
mental and lifestyle’s influence on genes.
opment) at the time of the change matter?
BIOLOGY OF AGING: RESEARCH TODAY FOR A HEALTHIER TOMORROW 17
GWAS approach does not require previous
ing condition. But by the time it reaches the
knowledge of the function of the gene or its
100,000 mile mark, the car doesn’t run quite
potential relationship with longevity, it could
like it used to. Or, that lovely walking path
possibly uncover genes involved in cellular
you discovered when you first moved into
processes and pathways that were not previ-
your home has now become weathered,
ously thought to play roles in aging. Since no
the weeds are overgrown, and some of the
single approach can precisely identify each
asphalt has buckled.
and every gene involved in aging, scientists
Like the car and the walking path, over
will use multiple methods, including a com-
time your DNA accumulates damage. That’s
bination of the GWAS and candidate gene
normal. Our DNA suffers millions of damaging
approaches to identify genes involved
events each day. Fortunately, our cells have
in aging.
powerful mechanisms to repair damage and,
As scientists continue to explore the genetics by and large, these mechanisms remain active of aging, its complexity becomes increasingly
and functional through old age. However,
evident. Further studies could illustrate the
over time, some damage will fail to be repaired
varying ways genes influence longevity. For
and will stay in our DNA. Scientists think this
example, some people who live to a very old
damage—and a decrease in the body’s ability
age may have genes that better equip them
to fix itself—may be an important component
to survive a disease; others may have genes
of aging. Most DNA damage is harmless—for
that help them resist getting a disease in the
example, small errors in DNA code, called
first place. Some genes may accelerate the rate mutations, are harmless. Other types of DNA of aging, others may slow it down. Scientists
damage, for example, when a DNA strand breaks,
investigating the genetics of aging do not
can have more serious ramifications. Fixing a
foresee a “Eureka!” moment when one gene
break in a DNA strand is a complex operation
is discovered as the principal factor affecting
and it is more likely the body will make mistakes
health and lifespan. It is more likely that we
when attempting this repair—mistakes that
will identify several combinations of many
could shorten lifespan.
genes that affect aging, each to a small degree.
Another kind of DNA damage build-up