Manipulating, removing, or transplanting ovaries has been shown to influence longevity in mammals - quite dramatically in the case of mice. Here are more examples, this time in dogs and humans: "The researchers collected and analyzed lifetime medical histories, ages and causes of death for 119 canine 'centenarians' - exceptionally long-lived Rottweiler dogs [and compared them] to a group of 186 Rottweilers that had usual longevity ... Like women, female dogs in our study had a distinct survival advantage over males. But taking away ovaries during the first four years of life completely erased the female survival advantage. We found that female Rottweilers that kept their ovaries for at least six years were four times more likely to reach exceptional longevity compared to females who had the shortest lifetime ovary exposure. ... The pet dog research [mirrors] the findings of the Nurses' Health Study published this summer by Dr. William Parker ... Parker's group studied more than 29,000 women who underwent a hysterectomy for benign uterine disease. The findings showed that the upside of ovary removal - protection against ovarian, uterine and breast cancer - was outweighed by increased mortality from other causes. As a result, longevity was cut short in women who lost their ovaries before the age of 50 compared with those who kept their ovaries for at least 50 years."