If the body continues to get rid of old cells and replace them with new ones, why do we age?

Answer 1

It not really due to the fact the errors creep in and we are so messed up that we "don't work" any more. Most cells in your body replicate and replace new ones ( except muscle cell, they don't replicate). It is also true that each time DNA is replicated, there can be mistakes along the way. BUT the cell has two system of correcting mistakes, one during replication and one after. These prevent major mistakes for occurring often, there fore each time the ENTIRE sequence is copied only about 3 nucleotides are changed (this is a TINY TINY amount). Even thought most of these changes do not affect the cell function (for reason i wont get into - msg me if you want to know more)

So on your DNA there are things called telomeres. These are "extras" on the end of your DNA so that when your DNA is being replicated near the end, the DNA polymerase (one of the things that copies your DNA) doesn't just fall off. Every time the DNA is copied, the telomere gets shorter. (PS.. Teleomere prevent mistakes at the end of the DNA sequence) Eventually when you are old, the telomeres is nonexistent, and more and more mistakes are allowed to be copied so more and more cell so not function properly, therefore we age.

Answer 2

I agree with the others. Errors creep in, nothing's perfect. As the errors multiply we eventually reach a point where we fall apart. I've heard that if you eliminated desease and accidents 120 to 130 would be the top end.

But there's something else involved. Each cell has a life. Its like a self contained timer the cell reproduces so many times then dies off. When that doesn't happen you have cancer. So there are some who say we have a timer when it plays out we're done.

I think its a good system. It would get pretty crowded if we didn't die off. Also the value of anything is always related to its availability. How much would a life be worth if you could live forever.

Answer 3

Every time a cell replicates, it changes ever so slightly. The thing which makes us age is that each reproduced cell has slightly less of some thing (I'm racking my brains, and I can't for the life of me remember what it's called).

To give you an anology, the cell is a pencil case. There is a part of the cell, a blue pencil, which isn't very importatn (i.e. doesn't hold data), but it is needed. Every time a new cell is made, it has a slightly shorter blue pencil than the original. Eventually the blue pencil is very short, and it results in ageing.

An interesting consequence of this is a problem with cloning, which happened with Dolly the sheep (the first ever cloned animal). If a cloned cell is made from a relatively old sheep, then it has a short blue pencil. Therefore at age 3 the cloned sheep has the ageing effects experienced by the 'mother' sheep at age 10 (for example). Dolly the sheep therefore died at a much younger age than her 'mother'.

Answer 4

My husband and I had a looong conversation about this the other day. I think it has to do with brain cells. Also, if you think about it like recycling paper, eventually you'll end up with very poor quality paper, or just a bit of mush. I guess the more you try to replace something the less perfect it is. What about our bones? We lose calcium as we get older, but is that a cell related issue? Personally, I think it comes down to the brain not functioning as well as it did when we were younger. The body is a machine, much as we like to pretend it's not... and machines wear out and break down with time. Long convoluted answer to a seemingly simple question. Have fun pondering. :D

Answer 5

Out of all the answers you have had, the correct one is the one mentioning telomeres. Whilst it is true that 'errors' creep into DNA copying, this is not the primary reason for aging. The shorter and shorter the telomeres get after so many cell replications, the older you will be!

Another prudent point to remember is if we didn't age, there would be no need to reproduce! Think about it.

As Richard Dawkins explains in the bestselling book 'The Selfish Gene': 'we are nothing more than gene-machines....temporary vehicles for the use of our DNA to get itself copied into the next generation'. After that....oldness, baldness, fatness for men and gradual loss of femininity, to put it finely, for the ladies...thats why grannies have moustaches etc.

Hope that helps.

Answer 6

We age because that pattern of cell replacement begins to slow and deteriorate after certain periods of time elapse. Take an original item of newsprint, or a photograph and make a copy of it. From that copy make another copy. From that copy make another copy. Eventualy you will reach a point where the copy produced will have lots of trash in it that was not there in the original material. This is similar to what happens in hundreds and hundreds of cell reproductions. The finest copies are the earliest ones made.

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Zahbudar
3rd Poobah of Mentawie

Answer 7

Natural weathering and breaking down of our dna replication system causines this, and the healthier you are the later it is put off-but also depends on your race-certain races genetical traits puts off aging -what you can see anyways, SO GRADUAL ERROsion in the dna duplicating system causing the gradual aging, and it gets worse over time as your mother can tell you..

Answer 8

Free-radicals

Answer 9

Each cell, no matter how old or newly formed, has a specific clock counting down. new cells don't have a freshly updated timescale.

Answer 10

Each time the DNA reproduces there are little errors copied over. Eventually they slow down and stop reproducing.