A discussion on published results from this primate study suggest that both it and a comparison study are different in ways that make it harder to pull rigorous conclusions from the data - beyond the fact that diet clearly has influence, and the effects of calorie restriction on life span (average and maximum) are expected to be smaller in longer-lived species versus shorter-lived speces: "Scientists have found that calorie restriction - a diet composed of approximately 30 percent fewer calories but with the same nutrients of a standard diet - does not extend years of life or reduce age-related deaths in a 23-year study of rhesus monkeys. However, calorie restriction did extend certain aspects of health. ... The survival results in the study reported [by] NIA researchers differ from those published in 2009 by NIA-supported investigators at the University of Wisconsin-Madison. The Wisconsin study followed two groups of rhesus monkeys for 20 years and found that monkeys on a calorie-restricted diet lived longer than those on a standard diet. Beyond longevity, the parallel NIA and Wisconsin studies have reported similar beneficial health effects of calorie-restriction. Both studies found that certain age-related diseases - including diabetes, arthritis, diverticulosis and cardiovascular problems - occurred at an earlier age in monkeys on the standard diet compared to those on calorie restriction. However, this observation was not statistically significant in the NIA study. NIA researchers did find that monkeys started on calorie restriction at an early age had a statistically significant reduction in cancer incidence. NIA researchers also found that while calorie restriction had a beneficial effect on several measures of metabolic health and function in monkeys who were started on the special diet regimen during old age (at 16 to 23 years), it did not have the same positive outcome for monkeys started on calorie restriction at a young age (less than 14 years). In the Wisconsin study, all the monkeys were 7 to 14 years when started on calorie restriction. ... Differences in the monkeys' meal and other nutritional factors were cited as possible explanations for NIA's and Wisconsin's different outcomes. Both studies used a similar percentage of calorie restriction with their intervention groups; however, the Wisconsin monkeys in both the calorie restricted and control groups were eating more and weighed more than the matched NIA monkeys. ... NIA researchers cited genetics as another possible reason for their differing results. NIA monkeys had a greater genetic diversity, originating from China and India. Wisconsin's monkeys came only from an Indian colony."