It is known for quite some time that while there are diseases caused by transcription errors, the only reason the occurence of those diseases increases with age is that the immune system becomes worse over time.
There are strong indications that aging, and dying, is an entirely programmed-in part of our genetic structure. We age and die, not because of DNA copy errors, but because DNA sabotages itself and the cell it's in over time. There are, of course, ageless cells. The most obvious example being procreation-related cells, but there's many different kinds (for instance, muscle cells have very different aging clocks).
Multiple "death clocks" have been identified, telomeres being the most famous, that measure number of cell divisions, others measure the amount of energy expended by the cell, genetic quality, and presumably a few other things. Exceed the limits on any one of them, and the cell commits suicide. But if you're close to the limit, the cells will "senescence", which means they'll be less active and less worried about making mistakes. But this is an active, controlled process, not an accidental result of gene degradation. All of your cells contain logic somewhat like this :
do_something() {
if (rand() > age/150) {
don't do it
}
if (rand() > age/300) {
kill the cell off
}
actually do it
}
The huge question now is : why is that logic there ? Presumably, there's a good reason (there always is for things in DNA). What, exactly, goes wrong when cells (and therefore people) are allowed to age without consequences ? Likely, we'll find the answer when we learn how to reset the clocks on a large scale in someone's body.
Also there are plenty of animals and plants, smaller ones, that don't age. Which has the surprising consequences that death (caused by old age at least) has an origin. There must be a point in history where evolution decided we'd grow old and die.
There's a very interesting book about this subject :
That aging is programmed is a minority view at present. Most researchers consider it to be a process of accumulated damage.
As to why aging exists in multicellular organisms, the evolutionary explanations tend to work whether or not aging is a matter of failure to evolve longevity-assurance mechanisms because selection pressure is low in post-reproductive life, failure to restrict selection of enhancements in youth that go on to cause harm in old age because selection pressure is low in post-reproductive life (such as an adaptive immune system that kills pathogens very efficiently in youth, but which goes haywire sometimes to attack the owners tissues, and suffers structural failure after exposure to too many pathogens), or a matter of the selected evolution of death programs. A compelling explanation is that species that age most likely outcompete those that do not during periods of environmental change.
There is no logic, because life do not do long term planning.
You don't have to go back many generations before being in your 40s was impressive. It was highly likely that the combined stresses of living would take you out in some way or other.
Once we reach the age of procreation, evolution is pretty much done with us.
> Once we reach the age of procreation, evolution is pretty much done with us.
It seems to me that the same argument could be used against the whole group of social animals. It doesn't work. Older people organize the group, they protect the young, ... One needs to look at evolution like it's at play for groups of people as much as it is at play for individuals themselves.
Besides there are many things that are tough to explain in evolution. Riddle me this. Humans are 7 billion, and have a generational length of 20 years, more or less. Bacteria are 9999999999 trillion (at least) and have a generational length that is somewhere between minutes and hours.
How do humans stay alive with that sort of competition ? Evolution becomes more efficient with shorter generational lengths and larger numbers of individuals. Sorry to break it to you, but bacteria have got us beat, by a LOT (and the gain should compound over time). Why haven't all larger plants and animals died out from infection long before humans or even mammals existed ?
There are strong indications that aging, and dying, is an entirely programmed-in part of our genetic structure. We age and die, not because of DNA copy errors, but because DNA sabotages itself and the cell it's in over time. There are, of course, ageless cells. The most obvious example being procreation-related cells, but there's many different kinds (for instance, muscle cells have very different aging clocks).
Multiple "death clocks" have been identified, telomeres being the most famous, that measure number of cell divisions, others measure the amount of energy expended by the cell, genetic quality, and presumably a few other things. Exceed the limits on any one of them, and the cell commits suicide. But if you're close to the limit, the cells will "senescence", which means they'll be less active and less worried about making mistakes. But this is an active, controlled process, not an accidental result of gene degradation. All of your cells contain logic somewhat like this :
The huge question now is : why is that logic there ? Presumably, there's a good reason (there always is for things in DNA). What, exactly, goes wrong when cells (and therefore people) are allowed to age without consequences ? Likely, we'll find the answer when we learn how to reset the clocks on a large scale in someone's body.Also there are plenty of animals and plants, smaller ones, that don't age. Which has the surprising consequences that death (caused by old age at least) has an origin. There must be a point in history where evolution decided we'd grow old and die.
There's a very interesting book about this subject :
http://www.amazon.com/Sex-Origins-Death-William-Clark/dp/019...