The New York Times interviews Elizabeth Blackburn on the topic of telomere science: "Telomeres are the protective caps at the ends of chromosomes in cells. Chromosomes carry the genetic information. Telomeres are buffers. They are like the tips of shoelaces. If you lose the tips, the ends start fraying. Telomerase is an enzyme. In cells, it restores the length of the telomeres when they get worn. As the ends of the chromosomes wear down, the telomerase comes in and builds them back up. In humans, the thing is that as we mature, our telomeres slowly wear down. So the question has always been: did that matter? Well, more and more, it seems like it matters. ... In my lab, we're finding that psychological stress actually ages cells, which can be seen when you measure the wearing down of the tips of the chromosomes, those telomeres. ... we looked at two groups of mothers. One had normal, healthy children. The other group had a child with a chronic illness. Physiological and psychological measurements were done on everyone. With the stressed group, we found that the longer the mothers had been caring for their chronically ill child, the less their telomerase and the shorter their telomeres."