A molecular “timer” implicated in ageing also has a profound effect on year-to-year survival in relatively young animals. If the same holds true in people, a simple genetic test may some day offer a peek at a person’s life expectancy.
Mark Haussmann and his colleagues at Iowa State University in Ames took blood samples from 22 one-year-old tree swallows near Ithaca, New York. For each bird, they measured the length of the repeated DNA sequences known as telomeres that cap the ends of chromosomes. Because telomeres shorten every time a cell divides, they set an upper limit on the number…
