One of the biggest lies in the modern world, used for insurance and pension purposes is that we are living longer.
a hundred years ago, there were many many factors skewing the "average" in a downwards direction
* being born (a lot of zeros pulls an average down quickly)
* giving birth (look in an old cemetery, many many female names in the 17-25 year range)
* Childhood Illness
* Accidental (throw child labour into those, eg chimney sweeps and cotton gins)
Once you got though those, the age at which you fall off the perch doesn't change greatly.
so yes, the "average" has increased markedly, but the end age hasn't changed much.
An Oz economist was talking to it a while back as a con...with the increase in people passing those milestones, you've got more people paying into taxes and funds, so using the "average" time of people receiving retirement benefits, based on an average that includes people who never got to that age (died very young due to the environment they were in), to delay retirement and benefits...is a con.