Beatrice Constantineau turned 104 last April.
"I have gout. My feet are bad so I can't walk too well. But other than that, I feel good," she said.
The oldest woman documented in the world was Frenchwoman Jeanne Calment, who died in 1997 at the age of 122 ½. In general, though, scientists say human beings hit a kind of "genetic" wall at 120.
Now researchers are working to break through that wall to extend human life span to as much as 150 years.
One of the most promising areas of research follows the principles of "caloric restriction" — severely limiting food consumption — as a way to live longer.
Mice have been shown to live up to 50 percent longer on severely restricted diets. Eating less appears to activate a gene that allows animals to survive longer on much less, as in times of famine.
Scientists say caloric restriction might also work in humans, but with side effects like weakness and loss of sex drive. So researchers are trying to develop a drug that triggers the same mechanism that makes you live longer but without starving yourself.
Lenny Guarente, a biologist at the Massachusetts Institute of Technology, hopes to test such a drug within 10 years.
"From experiments in the lab with animals, we can say that calorie restriction is going to make you live longer," Guarente said. "It's not 10 times longer. It's like 50 percent longer."
Dr. David Sinclair of Harvard Medical School has been chasing the same goal for the past 19 years.
"We've split the atom, as it were, in this field, where we've found the genes that control life span. I hope it's just a matter of time before we find drugs that can control these pathways," Sinclair said.
But some bioethicists argue that researchers should focus not on longer lives, but on healthier lives.
"What is the goal of medicine? Is it to increase the number of years in the human life span, or is it to improve health and cure disease?" said Harvard professor Michael Sandel.
The scientists say their drugs could do both by increasing resistance to disease, so people can live longer, better lives.