Hayflick limit

The Hayflick limit is the maximum number of times a normal human somatic cell can divide in culture, typically 40 to 60 times, before entering replicative senescence. Discovered by Leonard Hayflick in 1961, the limit is mechanistically explained by progressive telomere shortening with each division. It established that aging has a cell-intrinsic component and remains a foundational concept linking cellular replication, telomere biology, and organismal aging.