"Since the first cell culture was set at the beginning of the twentieth century it was believed that all cultured cells, if provided with the proper conditions, would replicate indefinitely. Sixty years later we overthrew this dogma by finding that normal cells have a finite capacity to replicate and that only abnormal or cancer cell populations can replicate indefinitely. We interpreted these findings to bear on our understanding of the aging process. If, as had been previously thought, normal cells can replicate indefinitely, then age changes could not have an intracellular origin. Our findings demonstrated that, on the contrary, age changes do have an intracellular origin. The hundreds of changes that were subsequently found to precede the loss of replicative capacity have been interpreted to be age changes and the finitude of replication to be an expression of longevity determination. Subsequent findings by others have determined the molecular mechanism that governs the finitude of normal cell replicative capacity and how immortal cancer cells escape this inevitability."

Leonard Hayflick Medicine See all quotes by Leonard Hayflick →

React to this quote

More by Leonard Hayflick

“Natural selection favors animals that are most likely to become reproductively successful by developing better survival strategies and greater reserve capacity in vital systems to better escape predation, disease, accidents, and environmental extremes. Natural selection diminishes after reproductive success because the species will not benefit from members favored for greater longevity. The level of physiological reserve remaining after reproductive maturity determines longevity and evolves incidental to the selection process that acts on earlier developmental events. Physiological reserve does not renew at the same rate that it incurs losses because molecular disorder increases at a rate greater than the capacity for repair. These are age changes, and they increase vulnerability to predation, accidents, or disease.”

“Age-related sensory changes can be traced to degeneration in some of the cells and cell products that compose the sense organ itself.”

Resonant Thoughts

"Slavery in the British colonies of North America was more than a century-and-a-half old before independence. It was roundly condemned, at one time or another, by nearly all the important political per…"

— Harry V. Jaffa

Philosophy1918–2015

#family

"The philosophy of Descartes underwent a great variety of unspeculative developments, but in Benedict Spinoza a direct successor to this philosopher may be found, and one who carried on the Cartesian p…"

— Baruch Spinoza

Philosophy1632–1677

#philosophy

"It is a new form of leadership of states, never encountered yet. I don't know what designation it will be given, but it is a new form. I think that it is based on this state of mind, this state of hig…"

— Corneliu Zelea Codreanu

Politics1899–1938

#leadership

"The rude, discursive Thinker is the Scholastic . The true Scholastic is a mystical Subtlist; out of logical Atoms he builds his Universe; he annihilates all living Nature, to put an Artifice of Though…"

— Novalis

Literature1772–1801

#life