Just a question for those of science out there. How does evolution influence longevity if at all or is this known? Are people now not living longer life spans and is this a result of an evolutionary process of some kind? If so, should we expect to live longer and longer and longer lives? If not, why does evolution not effect our longevity? Does the evolutionary process not center around survivability issues? Is the evolutionary process focused more on quality or quantity of life issues or is it 50/50?
evolution does not target longevity directly. for a mouse for example there is no need to live more than a couple of years if he can reproduce since 2 months old every 4 months or so. the survivability of the species(not the individual is what counts) if we want to live forever(even a couple hundred years would be nice) i think we need to skip evolution and work with DNA ourselves.
Originally posted by whodeyIt's just not that simple. If increasing longevity will not increase our fecundity, or the survival of our progeny in some way it will not be selected for. There is even a hypothesis that death of old individuals is good for their offspring, since it frees up resources.
Just a question for those of science out there. How does evolution influence longevity if at all or is this known? Are people now not living longer life spans and is this a result of an evolutionary process of some kind? If so, should we expect to live longer and longer and longer lives? If not, why does evolution not effect our longevity? Does the evolu ...[text shortened]... Is the evolutionary process focused more on quality or quantity of life issues or is it 50/50?
Your question is akin to asking "which is better, the annual plant wheat, or a perennial plant, such as an oak tree?" The answer is, of course, that a wheat plant is better at living the existence of an annual plant, whilst the oak tree is better at living the existence of a perennial plant.
The current rise in longevity is due to numerous factors, such as abundant nutritious food supply, medical advances, good hygiene, and things like that.
Originally posted by whodeyIn mammals longevity is closely coupled to metabolic rate.
Just a question for those of science out there. How does evolution influence longevity if at all or is this known? Are people now not living longer life spans and is this a result of an evolutionary process of some kind? If so, should we expect to live longer and longer and longer lives? If not, why does evolution not effect our longevity? Does the evolu ...[text shortened]... Is the evolutionary process focused more on quality or quantity of life issues or is it 50/50?
Mice have short lives as they need a high metabolic rate (most small hot blooded animals are the same).
If you calculate the number of heartbeats a mammal lives for, the number is remarkably similar.
Complex social factors will leed human evolution down paths that are hard to predict, some good some bad.
Genetic engineering for example. Stem cell reasearch nano technologies etc etc etc
it depends on which viewpoint you take. For example:
Evolution for humans is no longer occuring in a natural way as society is causing a "reproduction of the unfittest". Most career minded professional people are reproducing at a much slower rate than unemployed people who aim to live off the state.
Trailer trash could be seen as the future evolution of the human race.
Originally posted by whodeyI was reading some interesting work recently on the evolution of the human brain, which suggests that it might be the longevity of humans that has directly led to our bigger brain and greater intelligence than some other creatures.
Just a question for those of science out there. How does evolution influence longevity if at all or is this known? Are people now not living longer life spans and is this a result of an evolutionary process of some kind? If so, should we expect to live longer and longer and longer lives? If not, why does evolution not effect our longevity? Does the evolu ...[text shortened]... Is the evolutionary process focused more on quality or quantity of life issues or is it 50/50?
The argument goes that having older people around meant that they were able to better pass on experiences - necessitating improved speech centers for better communication, and more processing ability in the brain to enable people to understand and interact with the older people.
There's much more to it than this of course, but interesting stuff.
I don't think longevity is significantly improved now compared to earlier times. Most variation in lifespans is more likely due to imprvements in nutrition and medical care.
The survivability issues you mention refer to an individual's ability to reproduce. In evolutionary terms, once you've reproduced you're pretty useless.
Although, of course, older people can help to look after younger people - the development of the intricate social patterns of humans is probably a result of this.
Life expectancy may be getting longer, but where the extra years are being added is important to understanding further human evolution. Dividing life up into child (0-12), puberty(13-17), reproductive adulthood (18-50), and post reproductive (50+). The three first stages are remaining constant, while we are stretching out the golden years.
Evolution created aging as a tool to speed up evolution. A species that reproduced faster and died faster had more generations. Speeding up it's adaptation and evolution. Shorter life spans are an advantage and animals have genes that put a max on your life.
What eventually causes aging and death are Free Radicals breaking down cells. Your entire life Free Radicals are damaging your cells but your body produces chemicals to repair them. At around 60 years humans stop producing theses chemicals. There is no reason why, other then your body is programed to stop.
So even with all the advances in medicine, death is going to be around 80 to 100 in excellent circumstances. Unless we alter DNA, or mess up the cycle cell deterioration. Would that really be that good an idea? I think a balance of life and death is extremely important, and it's far to risky to mess with DNA.
Originally posted by Dave S 21I'm not sure that it's the human body that's programmed to stop, surely there would be a massive evolutionary advantage for someone who didn't age as they'd spend a lot longer passing on their genetic information. Would you say that a computer is programmed to break down after a certain length of time, or that it simply stops working?
Life expectancy may be getting longer, but where the extra years are being added is important to understanding further human evolution. Dividing life up into child (0-12), puberty(13-17), reproductive adulthood (18-50), and post reproductive (50+). The three first stages are remaining constant, while we are stretching out the golden years.
Evolution crea ...[text shortened]... nk a balance of life and death is extremely important, and it's far to risky to mess with DNA.
Originally posted by petrosianpupilDoesn't this mean that the increase in life expectancy is in fact not actually an increase, but simply a return to an innate capacity not realized for a very long time or across a broad enough spectrum of the population? It seems that because of a lack of competing adversarial conditions such as scarcity of food or lack of medical knowledge average ages have blossomed.
In mammals longevity is closely coupled to metabolic rate.
Mice have short lives as they need a high metabolic rate (most small hot blooded animals are the same).
If you calculate the number of heartbeats a mammal lives for, the number is remarkably similar.
It would appear that we notice things like an increase in average lifespan, but perhaps all it really tells us, is that more people across the board are having a greater access to an increased quality of life sustaining resources.
In absolute terms there have always been people who have lived to a very grand old age. All we are seeing is the same capacity extended to a greater proportion of the total population(noticeably within first world westernized countries)
Originally posted by mrstabbyBut that comes at the cost of having to keep the cells of that individual working at youthful levels. Don't you think it would be easier to let the individual die off and use its children and grandchildren to pass on the genes?
I'm not sure that it's the human body that's programmed to stop, surely there would be a massive evolutionary advantage for someone who didn't age as they'd spend a lot longer passing on their genetic information. Would you say that a computer is programmed to break down after a certain length of time, or that it simply stops working?
Originally posted by kmax87Yes, I think you're exactly right.
Doesn't this mean that the increase in life expectancy is in fact not actually an increase, but simply a return to an innate capacity not realized for a very long time or across a broad enough spectrum of the population? It seems that because of a lack of competing adversarial conditions such as scarcity of food or lack of medical knowledge average ages have ...[text shortened]... greater proportion of the total population(noticeably within first world westernized countries)
evolution works through the effect of some external criterion, on the success of reproduction of individuals within a species. the individulas who posess an advantage are favoured and perform better.
unfortunately reproduction is so easy in modern society and we are so protected from life threatening events that evolution is effectively stopped.
the soldier who is a little more cautious will still survive a little longer, those with tougher lungs will resist pollution better, maybe enough to reproduce before coughing to death? bird flu or some such disease may be the next thing to come along and take out the weaker of us.
evolution improves a species through the selection of the best equipped.
man is so dominant as a species that it can afford to have a high percentage of relatively weak and useless individuals. thats a good and a bad thing
Originally posted by eamon onot really good. all throughout history, species have perrished because they didn't have the power to adapt. so if situations change dramaticaly(nuclear holocaust) will mankind be able to survive?
evolution works through the effect of some external criterion, on the success of reproduction of individuals within a species. the individulas who posess an advantage are favoured and perform better.
unfortunately reproduction is so easy in modern society and we are so protected from life threatening events that evolution is effectively stopped.
the soldi ...[text shortened]... have a high percentage of relatively weak and useless individuals. thats a good and a bad thing
Originally posted by ZahlanziWell there's surviving and then there's surviving. Is it surviving if 99.99 percent of the human race is killed and the rest of the 6 million or so are living like cavemen?
not really good. all throughout history, species have perrished because they didn't have the power to adapt. so if situations change dramaticaly(nuclear holocaust) will mankind be able to survive?
Originally posted by amannionI couldn't say that's wrong, it may be true, but I wouldn't say it's a driving evolutionary force. I don't think any DNA repair system, even for bacteria, is perfect, in fact, it's the imperfection in DNA repair systems that allows evolution to occur in the first place. There are mammals who are less sociable than us, so for them an extended longevity would be a bonus, but this is rarely seen in nature.
But that comes at the cost of having to keep the cells of that individual working at youthful levels. Don't you think it would be easier to let the individual die off and use its children and grandchildren to pass on the genes?
Originally posted by eamon oI think there is still selection pressure for social adequacy, as those who are unable to cope with social situations may never reproduce, and thus be selected against.
evolution works through the effect of some external criterion, on the success of reproduction of individuals within a species. the individulas who posess an advantage are favoured and perform better.
unfortunately reproduction is so easy in modern society and we are so protected from life threatening events that evolution is effectively stopped.
the soldi ...[text shortened]... have a high percentage of relatively weak and useless individuals. thats a good and a bad thing