Over the past century or so, the average life expectancy has risen by about ten years, but this is more to do with the fact that more people are living to an older age, as opposed to an increase in actual lifespan. Despite all of our strides, only one person has lived past the age of 120 in all that time - so does this indicate that there is an upper limit on the human lifespan?
Many scientists believe that this invisible age barrier is the result of something known as the Hayflick limit. This is the limit on the amount of times a cell can divide before it is no longer able to. This limit varies between organisms, resulting in the short lifespan of a hamster, compared to a Galapagos turtle, and is thought to be a result of the shortening of telomeres - a section of DNA on the end of a chromosome that protects them from degrading.
It does seem that, for the moment, 120 years could be the limit of a "natural" human lifespan. That is, even if we do away with other causes of death such as disease, this would still be the point at which people would simply die of "old age". However, if we could somehow find a way of allowing our cells to divide and replicate without damage, we might, might be able to extend the human lifespan - perhaps indefinitely.
You could write for WhatCulture Science! Click here to find out how you could get paid to write about what you love.