There is no fixed limit to the human lifespan, says scientists who found that the chances to be a supercentenarian -- to live upto and above the age of 110 -- are high for people who survive the perilous 90s, and make it to 105.

The findings showed that the chances of survival for the longevity warriors plateaued once they made it past 105, challenging previous research that claims the human lifespan has a final cut-off point. People between the ages of 105 and 109, known as semi-supercentenarians, had a 50/50 chance of dying within the year and an expected further life span of 1.5 years. That life expectancy rate was projected to be the same for 110-year-olds, or supercentenarians, hence the plateau.

"Our data tell us that there is no fixed limit to the human lifespan yet in sight," said Kenneth Wachter, Professor at the University of California, Berkeley. "Not only do we see mortality rates that stop getting worse with age, we see them getting slightly better over time," he added. To date, the oldest human on record, Jeanne Calment of France, died in 1997 at age 122 years and 164 days.

According to researchers, those who survive do so because of demographic selection and/or natural selection. Frail people tend to die earlier while robust people, or those who are genetically blessed, can live to extreme ages, they noted. For the study, published in the journal Science, the team tracked the death rate of 3,836 Italians -- who were aged 105 and older between 2009 and 2015.

The result showed that Italian women born in 1904 who reached age 90 had a 15 per cent chance of dying within the next year, and six years, on average, to live. If they made it to 95, their odds of dying within a year increased to 24 percent and their life expectancy from that point on dropped to 3.7 years.