The phenomenon of limited cellular division was first observed by Leonard Hayflick, and is now referred to as the Hayflick limit. Significant discoveries were subsequently made by a group of scientists organized at Geron Corporation by Gerons founder Michael D. West, that tied telomere shortening with the Hayflick limit. The cloning of the catalytic component of telomerase enabled experiments to test whether the expression of telomerase at levels sufficient to prevent telomere shortening was capable of immortalizing human cells. Telomerase was demonstrated in a 1998 publication in Science' to be capable of extending cell lifespan, and now is well-recognized as capable of immortalizing human somatic cells.
Two studies on long-lived seabirds demonstrate that the role of telomeres is far from being understood. In 2003, scientists observed that the telomeres of Leachs storm-petrel (Oceanodroma leucorhoa') seem to lengthen with chronological age, the first observed instance of such behaviour of telomeres.
A study reported that telomere length of different mammalian species correlates inversely rather than directly with lifespan, and  concluded that the contribution of telomere length to lifespan remains controversial. There is little evidence that, in humans, telomere length is a significant biomarker of normal aging with respect to important cognitive and physical abilities.