(CNN) Humans can only live so long and we're reaching the natural biological limit, researchers say in a report published in Nature.
The paper, published Wednesday, says that despite life expectancy being dramatically higher than it was 100 years ago, it's highly unlikely it will continue to rise any more than what it is right now. It also says the probability of anyone living for more than 125 years is incredibly unlikely.
The research was carried out by geneticist Jan Vijg at the Albert Einstein College of Medicine in New York with several graduates. They analyzed aging trends in the United States, the United Kingdom, France and Japan.
In a statement released by the university, Vijg says that while "there is no reason to think that the ongoing increase in maximum lifespan will end soon," the data strongly suggests that it's "already been attained and that this happened in the 1990s."
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The report says that if a human lifespan was extended beyond 125 years, it would require other scientific interventions beyond improving someone's health. "Although there is no scientific reason why such efforts could not be successful, the possibility is essentially constrained by the myriad of genetic variants that collectively determine species-specific lifespan," it says.
Currently, the oldest documented person to ever live was Jeanne Calment, who died at 122 in 1997.
Professor Dame Linda Partridge, director of the UCL Institute of Healthy Ageing, told CNN that while some of the report's conclusions are perfectly sound, others are questionable.
"A biological time bomb won't just set off," she jokes. "Clearly if we're seeing someone who's 100 years old they were born 100 years ago -- in 1916 -- and the conditions there were completely different than those faced by babies being born now."
"There was loads of infection diseases, there was war, the quality of food wasn't good -- you can go on and on," Partridge adds.
She says the living conditions were much harsher than those now, "so we can't really project (the lifespan of) babies who are being born right now."
Director of the UK-based Biogerontology Research Foundation Alex Zhavoronkov agreed the report is "scientifically sound," but told CNN "there is every reason to believe that with more serious interventions into the biology of aging, we can live substantially longer."
Despite living conditions being better than they were 100 years ago, Partridge also raised concerns about children growing up now.
"Obesity is a huge tragedy," Partridge says."They're growing up very unhealthy (and) we need to do a lot more work on the long-term consequences. Their prospects can't be good."
Partridge admits there's definitely a limit to how long humans can live.
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"It's not biologically feasible to live to 3,000 years. There's constraints on how fast we run, speeds at which we can see. So without any further interventions, bodies can only last a certain amount of time," she says.
Partridge suggests if people do want to live a long and happy life, they should stop smoking, start exercising and eat a healthy diet. But while there is a limit to how old we can grow, she says it's not something people should worry about.
"What will be will be. It's only a question of when."