Since they seem to be quite connected, I'm curious if anyone knows of research comparing the Hayflick limit (and presumably by extension telomere length) between different taxa. I've heard the Hayflick limit numbers 40-50 thrown out repeatedly for humans (probably relating to the WI-38 tissue line), but how universal is this really? I Know there are particularly long lived species, but has research been done to correlate this with telomeric length, or do they simply have slower cell division? I suppose it is worth mentioning that a Hayflick limit of 40 rounds of division is massively different from 50, since each round of division conceivably could double the number of cells...
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Many studies, including those of Hayflick himself, have found a strong correlation between a species' Hayflick limit and its maximum lifespan. For example, Galapagos tortoises, which can live over a century, have a Hayflick limit of 90-125, and mice, which live only a few years, have a Hayflick limit of 14-28.
However, the mechanism connecting the maximum number of cell divisions and maximum lifespan is not entirely clear. Cell division is associated much more with growth and development than with the maintenance of mature tissues. Cells that have stopped dividing can be perfectly functional for decades. Cells that don't stop dividing are called "cancer". So, while the correlation is strong, the reason for the correlation remains something of a mystery.
Rose, Michael R. 2005. The Long Tomorrow: How Advances in Evolutionary Biology Can Help us Postpone Aging. Oxford University Press, New York. pp 20-23
