COLUMN: You really aren't as old as you think
I respect my father. He is an educated and responsible member of society. That being said, he is getting rather old, as he has been constantly reminding me as of late. Just the other day he was whining to me about how his old bones can’t carry him up the stairs. This comment got me thinking. Are his bones actually as old as he claims?
Turns out that they sure aren’t. A few years ago, Jonas Frisen of the Karolinska Molecular Biology Institute in Stockholm used C-14 carbon dating to determine the ages of various tissues in the human body.
Frisen’s measurements, published in the July 15, 2005, issue of the esteemed journal Cell, showed that most cells in the body have a relatively short life span. Average life of cells in various tissues, as estimated by Frisen and others, is as follows:
• Cells lining the intestines: 2 days
• Skin cells: 30 days
• Red blood cells: 120 days
• Liver cells: 300 to 500 days
• Muscle cells: 15 years
• Cells in my dad’s bones : 10 years
There are some cells, such as neurons, that do not have the ability to replicate and are indeed as old as the day they were born. But, most cells are short lived: The average age of cells in the human body is seven to 10 years.
Back up. If our cells — the lego pieces of our bodies — are about the age of a fourth grader, why do we age anyway? Shouldn’t we live forever?
While it may seem this way in theory, there is a caveat. While new cells replace old cells, each new cell comes from the division of an old cell with DNA providing the genetic code.
Though the science of aging contains much theory and many unanswered questions, we do know that our DNA can be damaged during replication as new cells are formed, and this damage can accumulate over time. Accumulated damage in DNA hinders the normal function of cells and can lead to many of the problems we colloquially chalk up to “old age.”
So, I can now tell my dad that his bones are not, in fact, too old to climb up the stairs. For the tenured professors out there who are thinking of retiring, remember that you are not quite like a 65-year-old car. Instead, you are a 65-year-old car on which the majority of the parts are brand new, but you didn’t buy them from necessarily the best manufacturer. Most of your body is actually “younger” than me.
— Jay Kumar, microbiology sophomore