The FOXO3A gene is linked to the web of biochemical research surrounding calorie restriction, sirtuins and calorie restriction mimetics, and the rest of the major efforts in understanding how metabolism determines longevity. It is the human version of a gene already demonstrated to influence longevity in lesser animals: "A variation in the gene FOXO3A has a positive effect on the life expectancy of humans, and is found much more often in people living to 100 and beyond - moreover, this appears to be true worldwide. A research group [has] now confirmed this assumption by comparing DNA samples taken from 388 German centenarians with those from 731 younger people. ... We have now eliminated that uncertainty about the connection between FOXO3A and longevity, both by our results from the German sample study and by the support from our French partners in Paris, whose research on French centenarians showed the same trend. ... We can now conclude that this gene is probably important as a factor in longevity throughout the world."