X-Message-Number: 11873 From: Thomas Donaldson <> Subject: For Robert Moore: more about the evolution of aging Date: Wed, 2 Jun 1999 23:52:59 +1000 (EST) To Robert Moore: If you want to know more about evolutionary theories accounting for aging and lifespan you might first look at the papers I cited in my posting for the previous Cryonet. However you do ask some questions worth answers. The very first point I will make is that for men at least, there is no time at which the man cannot sire a child. This means that someone who lives to 70 has a greater opportunity to produce more children than someone who only lives to 60. Moreover, even for women, before 1850 everyone was old at 40, and menopause played no special role. We see it now because women are living for longer, too. For men at least, there is no upper lifespan beyond which they cannot produce children. If this is true for men, then the genetics involved suggests that women would carry similar genes, too. Basically, though, it is simply false that after a certain age we can do no more than help our previous progeny to survive. Not only that, but even now particularly prosperous men WILL produce children at high ages by wedding a much younger woman. The paper by Hamilton even goes into detail about just how strong the selection will be given the kind of factors I have discussed here. Yes, it's true that at lower ages right now the selection is stronger; but it only becomes weaker as we age, it does not go away. Hamilton discusses that kind of selection as different functions depending on age of abstract animals. It's also reasonable to ask about those who, even in Roman or Greek times, lived to what we still consider a high age. The really important thing to understand here is that such people in the mass of the population were extremely rare. We may remember them because of what they did, but in terms of reproduction (producing children) they were so rare that they did not have any GENETIC impact on the rest of the human race. The remarkable thing that is happening now is that such high ages have now become the norm, rather than the exception. Not only is this a matter of theory, but some students of aging have looked at records of lifespans over time. For Christian burials this is a lot of work but the information is often right there on the tombstones. It turns out that until about 1800 (when a bulge had appeared in the general lifespan curve, which become higher and stronger into this century) a graph of lifespans did not look at all like the one we see now. Instead it looked exponential... with time, more people died at a constant exponential rate (as you can guess, that rate was much higher than at present). You might look in your nearest academic library for the HANDBOOK OF AGING (Biological section). It is a collection of papers on all the different sides of aging. Our picture of the past, now, is badly skewed by the simple fact that we hear nothing from those who were illiterate (the large majority) but only from those who were literate and in the upper classes. These were people who lived quite exceptional lives compared to that of the rest of the human race living at that time. In terms of what people of the time understood, they knew that death would come to everyone ie. that there was such a thing as aging, but it was far from the most prominent cause of death for most people ie. the peasants and the poor, who had no voice in history. You've also probably heard of some people such as the Pygmies who are said to believe that death is always caused by some kind of magic directed at the person who dies ie. that it is not at all the "natural" state of affairs. Since their deathrate curve was exponential, they weren't really all that foolish in their belief. They simply had never encountered aging in the way we have. There is also a strong suggestion in the Epic of Gilgamesh, which comes down to us from the very earliest urban civilizations, that the realization that death came to everyone occurred AFTER we began to live in cities and a very small minority of the population lived long enough to die of aging, not of any bacterial or viral disease or injury. Since people aren't stupid, such a realization would also spread to those who did not live in cities, too... unless they were isolated enough. Finally, I hope you understand that I'm not just giving you my private opinion. Thinking about EVOLUTIONARY causes of aging has gone on for some time, as you can see if you read the papers I suggest. I don't claim any originality here, but I will say that these ideas don't seem to have spread as far as they should. Best and long long life to everyone, Thomas Donaldson Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=11873