Just how long can humans live? Biologists at Montreal's McGill University have been studying the question and say if there's a limit, they haven't found it. "We just don't know what the age limit might be," said Siegfried Hekimi. "In fact, by extending trend lines, we can show that maximum and average lifespans could continue to increase far into the foreseeable future." A previous study looked at the lifespan of the longest-living individuals from the U.S., the U.K., France and Japan for each year since 1968 and concluded that the maximum human lifespan is approximately 115 years.