Human Body

[d9f1c7]

I watched a science/biology documentary recently where they said that very little of the human body is older than about 15 years at any one time, ie due to cells getting replaced and general regeneration. If that's true why do tatoos not just disappear over time?

[sandyRoe]

The ink is a foreign substance lodged under the skin? They do fade over time.

[emmie]

as sandy says they do fade, it's the reason, though not the only one i wouldn't have one done. My nan had one done as a young woman, and as she got older you never could tell what it was, her mother must have gone mad at her.

[JonnyBoy12]

Good question. Why do people age then and not stay forever young?

[EvianBaby]

My dad got an eagle on his forearm about 40 years ago. Now it just looks like a nasty bruise. Lol

[jomifl]

The tattoos do not get replaced by the body's renewal mechanisms because they are foreign matter so the body does not have the chemical processes to handle them. Although skin is being replaced by new skin that is produced underneath the old skin the tattoos are injected below the level of generation of new skin so they don't get carried to the surface.

[d9f1c7]

i see, thanks

[Wak]

JonnyBoy, I suppose people age because we are like motor cars and the repairs are not quite as good as the original bodywork!
Does that make sense?

[jomifl]

We age because we have evolved to age. We only need to live long enough to set the next generation on it's way, that's the best strategy for humans otherwise we wouldn't have evolved that way.

[Old_Geezer]

People age because the replacement mechanism isn't perfect and errors accumulate. As long as a species stays alive long enough to produce the next generation there is no drive to improve further. Over time your telomeres eventually wear away, your chromosomes become more susceptible to damage and things don't get replaced quite as they used to be.