Do we not understand enough about the human body? I have heard that we don’t fully understand the mechanism behind aging and this got me wondering. I mean our body seems to be like one of the first things we’d investigate, and yet we seem to know less than I had originally thought.
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An emerging way of framing aging is as cellular information loss.
Your cell doesn’t know how old it is, in fact most cells are constantly either dividing or being renewed from stem cells (also dividing).
This means there are few cells as old as you are. Your cells don’t know if you are 15 or 150. In fact there are plenty of examples of longer lived species (whales, trees, turtles etc)
So it must be the information that the new cell gets from the old cell that is somehow getting “older.”
This means it must be connected somehow to DNA, since the rest of the new cell gets built from the DNA of the old cell.
This is like having to build a new building every time from a blueprint but during construction and while you have the building your blueprint keep getting coffee stains and tears and scratches on it. You keep repairing it but eventually the mess adds up and the blueprint stops being readable. You lose track of which floor gets the stairs and where the foundations go.
The DNA equivalent of a coffee stain is DNA damage (from UV, free radicals, that ultra-processed fluorescent mac &cheese you ate etc). This damage is usually repaired but sometimes it gets repaired wrong, and you get mutations and epigenetic drift, a fancy way of saying the wrong parts of the DNA become silent and active.
Once this information is lost, there is no easy way to fix it, since your cell doesn’t have a third copy. In fact this is the reason you get two DNA strands to being with, it’s more robust than just one.
One solution is you can get rid of the old cell, which your body does all the time, but eventually you run out of “fresh” cells or stem cells, since they too get too much information loss and noise.
Without a way to return this information to the cell, I.e fix the blueprint, eventually cells start to grow out of control (cancer) or start being toxic (senescent), or just don’t work really well.
Eventually tissue and organs start to fail and something important stops working, which kills you. We can this dying of old age.
This means that although it’s absolutely complex and multifaceted, there’s actually a central locus we can target: DNA information loss in the cell. There are now numerous startups working on this issue, and really ground breaking work happening in this area.
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