Starvation's Longterm Effects
During the winter of 1944, famine caused by a German blockade in the Netherlands resulted in a generation of children with higher rates of diabetes, obesity and schizophrenia than normal.
For many years, the underlying mechanism behind these responses was a mystery. DNA had not changed in a generation, so, what was happening?
Today, the study of heritable changes that are not caused by changes in DNA is known as epigenetics.
Scientists have discovered that changes in gene expression can be caused by many factors. Certain base pairs in DNA, or RNA, can be "turned off" or "turned on" again, through chemical reactions. Repressor proteins can silence regions of the DNA, and entire X chromosomes can be inactivated.
Small RNA Inheritance
One mechanism being researched is called small RNA inheritance. Small RNAs work by shutting genes off, or occasionally by turning them on.
A large group of scientists studied worms that were starved early in their development. They found that the worms responded to starvation by producing a variety of small RNAs. They also discovered that some of those small RNAs targeted genes involved in nutrition.
Surprisingly, those small RNAs were inherited by at least three subsequent generations of worms. Not only that, the great grandchildren of the starved worms lived longer than worms where no starvation occurred.
This study showed that small RNA inheritance is an important mechanism. Understanding epigenetics could lead to a better understanding of how organisms can adapt to ever-changing environments.