Environment and the Genes
By: S.S.
Agarwal
Man-made degradation of the environment is a cause of global
concern.
No one can escape from the visible scars of so called 'human progress'
which means consumption of natural resources without concern for their sustenance.
For developing countries, not only is the time running out, but the greatest
expectations for improving living standards (requiring industrialization)
on one hand and rising population on the other, contributing to resource
depletion and pollution, have created a dilemma in choosing environmental
priorities. In this context the examination of the great strides that are
being made in the field of genetic engineering and their potential to contribute
to environmental health has been proposed.
The relationship between the environment and genes is eternal. One
does not have to go far to see the effect of the environment on the expression
of genes. Classical studies on monozygotic twins reared apart on several
genetic traits such as intelligence, obesity, diabetes, and maniac depressive
psychosis, etc., have clearly shown the role of 'nurture' in determining
the outcome of nature, i.e., the genes. Even in single gene determined
traits, the environmental factors play an important role in the expression
of genes. For example, a child homozygous for phenylketourea (PKU) will
not manifest mental retardation, if phenylalanine is eliminated from diet.
Besides PKU, there are several other inborn errors of metabolism, including
hyperlipidiemia, obesity, gout, etc., where the course can be modified
by dietary manipulation. Thus the fields of Nutrition-genetics and Pharmaco-genetics
have extended on to merge as an important discipline of Eco-genetics. The
scope of eco-genetics can easily be appreciated if one looks into the mysteries
of ready adaptability of human genome to extreme variations in environment
ranging from deserts to polar ice caps on one hand; to deep-sea to high
altitudes, including space without gravity, on the other.
While considering the effect of environment on genes, the mutagenic
and carcinogenic potential of ionizing radiation and various chemicals
has been a cause of great concern.
In a lighter vein, the matter to ponder is whether in the absence of
mutations would man have evolved? Man-made progress is squarely blamed
for environmental degradation, but what would have happened if man was
not there? For millions of years when man was not present on the face of
the Earth, was the environment static? Why were there glacial ages? Could
not the great apes might have followed the dinosaurs into oblivion? Then
why blame man alone for environmental degradation. It is another matter
that man-made evolution might have speeded up the process, but then why
could it not be considered to be a path of natural evolution, leading to
disaster? Why should not we take a positive view, that it may be because
of man that the disaster maybe averted.
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