Some human beings alive today will live to the age of 150, a prominent researcher has claimed.
Some women in the UK are now reaching their 12th decade
Steven Austad, of the University Of Texas Health Science Center, told BBC World Service's Discovery programme that life span for a human being may be much longer than most people have considered possible.
And he said that he was virtually certain some children alive now would live to the year 2150.
"The evolutionary picture of the human being is quite an interesting one, because what we've managed to do is create an environment for ourselves that is much safer than anything we've lived in before," he explained.
"So even in the absence of medical advances, with just evolutionary change, in the foreseeable future one would expect humans to age at a slower and slower and slower rate."
In the industrialised world, more and more people are living even into their 90s and 100s - and there is no sign yet of the trend levelling off.
It is this that is causing, for example, fears of pension crises in many Western countries.
But it is also evident than in some pre-industrial societies around the globe today, there are people who are surviving into their 70s and 80s, despite a lack of, for example, readily available medicines.
Dr Austad's prediction relates in part to research designed to understand how long human beings would actually live for if left in the natural world.
Wasps that work together live a lot longer than solitary species
Jim Carey, a biodemographer from the University of California at Davis, analysed the relative body and brain sizes of a range of mammals and found that on our own, it would be likely we would die at between 30 and 40 years old.
The fact that we do not is down to two factors: our brain size and our sociality - the ability to specialise and act together.
Dr Carey explained that the brain, being the instrument of social behaviour, is the key.
"We would estimate that humans would live for 30-40 years just based on size," he said.
"But sociality - and more specifically brain size - comes into this, and brain size and sociality are also related.
"So when you factor in the brain size on this, then you get an estimate of 70-90 years for the human life span."
Dr Carey explained that in the natural world, it has been observed that solitary wasps have a life span of 10 days to two weeks - but advanced, social wasps can live for two to three years.
In other advanced social groups of insects, such as termites and ants, the Queens can live for two or three decades.
"Once you have helpers, plus a nest, the mortality conditions and risks are a bit different," he added.
Evidence that of our ancestors lived beyond 40 is scarce
"The nest provides protection, but also with helpers, you evolve defensive behaviour. You start specialising so that the mother can be reproductive."
Similarly, lions, which live in social groups, live longer than tigers, which are essentially solitary.
And there is very little evidence of our nomadic human ancestors living into their 40s or 50s.
"We are left with the idea of explaining why we humans live much longer than we should for our body size," Dr Austad said.
"One reasonable guess about why that may be true is that we live in these complex groups that provide us some protection that we wouldn't have if we were out there on our own."
Meanwhile, he added that he was so certain that someone alive today will still be alive in 2150, he had placed a bet on it with a friend.
"It's a bet that I feel I'm so overwhelmingly likely to win, I feel like I've stolen the money from him."