Happy Atheist Forum

Hey gang,

I was wondering: How much of our body is replaced over a given time?

For example, I'm 45 (ish).  How much of my 20 year old self remains?

Skin, hair, nails, organs - cells get replaced all the time.
Aging happens (sheesh!)
Plus medical issues, replacements (most of my teeth have fillings), etc.

It's amazing our sense of "Self" remains intact.

So, does anyone know how much of me is still me?

Confusing myself,
JoeActor

To add to that, how many people still feel like they are exactly the same person they were 10, 20, 30 years ago?

I have no idea what percentage of me has been replaced, but I do know that the me of today (44) is not the me of yesterday (20). And though today me is working hard doing things for tomorrow me (65), I doubt he will appreciate it much, if at all. Tomorrow me will probably resent today me for not doing enough to make him financially confortable and physically healthy, try as today me might.

Daniel Gilbert's book about our brains, "Stumbling on Happiness" explains this concept very well.

Perhaps this belongs in the Philosophy section?

But seriously, I think all our cells are pretty much replaced every 7 years. I don't think brain cells are replaced though (I may be wrong) and that is where our consciousness lives.

Many cells are replaced every seven years or less, but IIRC neurons live a lot longer. Most of the same neurons I used to learn the piano at age 5 will still be in my body at age 85.

Quote from: "Will"Many cells are replaced every seven years or less, but IIRC neurons live a lot longer. Most of the same neurons I used to learn the piano at age 5 will still be in my body at age 85.

Hmmm... interesting.

So, how about this:  If your neurons were slowly replaced over time, would you still be you?

Reminds me of the Steven Wright Line:
I woke up one morning and everything in my apartment had been stolen and replaced with an exact
duplicate. My roommate was on the couch, so I asked him, "Hey, did you notice that everything in the apartment has been stolen and replaced with an exact duplicate?" He just looked at me and said, "Do I know you?" - Steven Wright

I'm also not so sure my other organs aren't used in the whole "me being me" equation.

Not sure how I'd even test it,
JoeActor

If my neurons were slowly replaced over time, I'd need to relearn things a lot. I probably wouldn't have many memories beyond whatever point neurons died and were replaced, so yeah I'd be a new me.

On the up side, brain damage would heal much better if I were ever in an accident.

I know this isn't exactly what you mean but it's sort of related  

Quote from: "Steve Grand"Think of an experience from your childhood. Something you remember clearly, something you can see, feel, maybe even smell, as if you were really there. After all, you really were there at the time, weren’t you? How else would you remember it? But here’s the bombshell: you weren’t there. Not a single atom that is in your body today was there when that even took place… Matter flows from place to place and momentarily comes together to be you. Whatever you are, therefore, you are not the stuff of which you are made.

A decent percentage of the DNA that was in you, say 20 years ago, has been conserved or incoreporated into semi-conservative DNA strands. The same strands with the same atoms you were born with, plus quite a lot more that has been added ever since, minus a lot that you have lost...but the exact figures I'm unsure of...

Other cellular components, its a similar story, although none have quite the permanence of DNA, so I'd say a much lower % is conserved. Obviously there would be more atoms/molecules conserved in a non dividing cell.

JA is spot-on, it leads to some big questions that science cannot answer easily...however, thats no excuse for not trying...

I'm a biochemistry student, so maybe, just  maybe, one day, I will write a groundbreaking paper about the answer to the question, what makes us us, in purely naturalistic terms.

 

Dreaming On

Templeboy

Good info everyone.  I'd heard the "7 year" figure before, but hadn't realized about dna being conserved.

I agree, templeboy - gotta keep asking the hard questions and searching for answers.

Science!

There was an interesting book I'd read a while back - "Panati's Extraordinary Endings of Practically Everything & Everybody".
They were relating death to sex, and implied that simple organisms like amoeba might be considered immortal...
(Off Topic!)

Anyway, thanks for the new info,
JoeActor

"Me" right now is using mostly the same wetware it was 21 years ago but since then some hardware (wetware?) has been lost or corrupted (brain damage and a tumor plus aging), quite a few files were lost or corrupted due to damage and the passage of time, I've picked up a few pieces of malware, and added and subtracted some programming.  If we go by the entire hardware package, yes, I'm the same "me" with some wear and tear and replacement parts.  But if we go by the running of programs, I'm a very different "me" indeed.

This reminds me of my old ethics class back freshman year. That old thought experiment: if you copy yourself completely, memories, personality , thoughts, biology, scars, everything, is that copy you? If the first "you" dies, do "you" still live on? It's all about where consciousness resides.

Quote from: "curiosityandthecat"This reminds me of my old ethics class back freshman year. That old thought experiment: if you copy yourself completely, memories, personality , thoughts, biology, scars, everything, is that copy you? If the first "you" dies, do "you" still live on? It's all about where consciousness resides.

I would say it was me at the point of copy but then would cease to be me from that point due to having different life experiences.

You people have sparked my interest and i'd hate to be an ass (thats always how it starts when I piss people off >.<) but can you post links to where you are getting your info from?  I'm not accusing anyone of pulling info out of their ass or anything :-p but i'd like a point on where to start.  By the way Sophus i've seen that quote before but I thought I saw it in a Richard Dawkins book.  It gave me the chills when I read it.  Anyway thanx in advance.

You are the processes, not the materials.

This reminds me of a slower more naturalist version of the the Clone/transporter moral paradox.

Quote from: "jbeukema"You are the processes, not the materials.

Yeah I agree. And I think the processes would diverge at the point of split on account of receiving different sensory input.

The psychology textbook I've been reading says children learn to identify themselves around 15 - 18 months. By age 8 - 10 they have a stable sense of self image.

But I think it's all a big (though useful) evolutionary trick! There is no self as we think of it, just a sophisticated parallel process running in a brain. The idea of cloning the process seems mind blowing because it's at odds with our inaccurate concept of self.

Quote from: "AlP"

Quote from: "jbeukema"You are the processes, not the materials.

Yeah I agree. And I think the processes would diverge at the point of split on account of receiving different sensory input.

The psychology textbook I've been reading says children learn to identify themselves around 15 - 18 months. By age 8 - 10 they have a stable sense of self image.

But I think it's all a big (though useful) evolutionary trick! There is no self as we think of it, just a sophisticated parallel process running in a brain. The idea of cloning the process seems mind blowing because it's at odds with our inaccurate concept of self.

I don't remember who said this about our perceptions but, "Our world view is very messed up.  We are on a rock, mostly covered in gas, circling a giant fireball and we consider this normal." (come to think of it Dawkins might have said it) Our brains still have a hard time grasping the very large (cosmos) and the very small (atoms).  Unfortunately most days we have to work under the assumption that what we perceive is accurate though it really isn't.