One of the workhorses of longevity studies is a little flatworm called C. elegans. Lots of scientists have come up with lots of ways to get these little guys to live longer than usual. With enough tinkering, they can live 4 or 5 times as long as their wild brethren. That's like a human living to be 500!
Work out of the Brunet lab at Stanford added another chapter to this story. They tinkered with how a worm uses its genes and found these worms lived around 25% longer than normal.
That’s old news though. What is exciting is the new study that shows that the worms passed this trait down to their kids and their grandkids.
These worms inherited the pattern of how their genes were used from the original parent. And now the kids and grandkids live longer than worms that have the exact same set of genes. All because of how an ancestor used its genes.
The effect is not forever though. The great grandkids live about as long as worms with the same set of genes. Apparently gene usage patterns reset to normal after three generations or so.
As you’ve probably gathered, how our genes are used is as important as the genes we have. For example, every cell has the same set of genes. And yet, a blood cell is wildly different than a muscle cell. The difference comes from how each cell type uses the genes it has.
A big part of how a gene gets used is determined by various chemical marks attached to either nearby DNA or to the spools around which the DNA is wrapped. In this case it has to do with chemical marks on one of the worm’s spools or histones.
Most of the marks on DNA and histones are wiped clean once they are packed into a sperm or egg. This allows the fertilized egg to develop into all the different cell types needed for an adult worm (or person).
The specific changes made in this study linger for awhile longer and take three or so generations to wipe out. We don’t exactly know why yet but we do know that this is what we often see with epigenetic changes like this.
Epigenetics is a fancy way of saying something is passed down without a change in the gene itself. As scientists delve deeper and deeper into genetics, they are finding many traits that behave this way. Even in people.
So is this going to make us live longer? Not yet.
But it does suggest that if we can one day mimic these effects with a chemical, we may end up living longer. And so will our kids even if they don’t pop the same pill.
Cynthia Kenyon talks about one particular long lived mutant.