What is the Hayflick limit for humans?

Question

I've been told that an absolute age limit, absent major biological reconstruction, has been calculated for a number of species.

This limit is supposed to have been calculated by a researcher named Hayflick, based on the number of times various types of cells can replicate themselves before accumulated duplication inaccuracies render the cells non-viable.

Can anyone tell me more about this Hayflick, and the research project he was working on when he calculated these limits?

What is the age limit for humans?

Is it true that there has been a mouse that has outlived the Hayflick limit for its species after being given some sort of treatment?

Can such a treatment be developed for humans?

Answer 1

I have not heard of the Hayflick limit, and I don't believe in looking up stuff in a wiki for you.  (You can do that yourself, and I assume you want something more.)

What very little I have read indicates that there are 2 factors that determine the ultimate age we can naturally achieve.

First is the hypothesis that our cells have a built in limit to the number of times they can replace themselves to protect us from cancer.  This seems very plausible to me.  It would be like a cellular firebreak.

The second idea is that our age is shorter than it can be because we procreate at a young age.  If we had a population that held off having children until 40, and then the next generation waited 10 more years and so on and so forth.  Through artificial selection it is possible that there would be no upper limit to our age, given enough time and a large enough population.

As older and older populations procreate, there would be a progressive culling of those who have congenital defects that are late appearing.  Eventually, many health problems would either go away or manifest at later and later ages.

Answer 2

The Hayflick limit more refers to cells in culture than to cells within an organism.

Also - there are some cell types which (it is believed) do not obey the Hayflick limit. Cancer cells are the archetypal example - but other non-disease cells also do this: germ-line cells and stem cells (as long as they are maintained in a non-differentiated state).

There are several proposed mechanisms for aging - not just the limit on the number of divisions a cell can go through. The field investigating this is called "gerontology" (the science studying aging), and aging is referred to as "senescence". Looking up both those terms will give you a better idea of the current state-of-play as far as human aging goes.

Another subject you might find relevant is Aubrey de Grey, and his idea of "Engineered Negligible Senescence".