Expert: Dana Krempels, Ph.D. - 1/10/2011

Question
QUESTION: What is the life-span of a human cell?  I understood that all cells die after about 7-10 years, except brain and cancer cells. I have just watched a Richard Dawkins video in which he states that all our cells die and are replaced every few years.  Which is the correct answer, please.  Many thanks.

ANSWER: Dear Dave,

Dr. Dawkins was probably speaking in generalities when he said that.  The lifespan of a human cell depends on its identity.  Each tissue type cell has a specific lifespan, and you can find a sampling of them here:

http://vitanetonline.com/forums/1/Thread/1001

These are averages, of course.  Hope that helps!

Dana

---------- FOLLOW-UP ----------

QUESTION: Very helpful, but didn't mention brain-cells. Do you know their life-span?

Answer
Dear Dave,

Brain cells, like any other neuron, must last the lifetime of the individual human.  Most neurons finish reproducing and gaining their final function in our very early childhood (before the age of five), and that's it.  This is why central nervous system injuries are so devastating:  once a neuron is destroyed, the remaining ones cannot divide to replace it.

So the answer to the lifespan question is:  it depends.  In most humans, brain cells do start to die off as we reach into the late lifespan ages.  But obviously, people who live to be 100 and more have brain cells that are as old as they are!  There is probably a great deal of variation in brain cell life span across individuals.  But individual brain cells can live for many, many decades.

Hope that helps.

Dana