saw a recent piece, it stated every 5 years a humans's atoms are different to what they had previously, dont change all at the same time !!. anyway the implications, are strange, for we are not us anymore. the fabric of our very self is not the same as when we had our first kiss, we are not the same being anymore. so lets apply this to our brain, er it's as weird as quantum physics, it may explain why we get so involved with nostalgia, for thats one thing we think of as us in the past or is it ??