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Vol. 1 No. 4 - October 1995

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.

This article has been reproduced from the archives of EnviroNews - Newsletter of ISEB India.

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