Thread: Could all humans be predispositioned genetically to die due to a natural population control?

I'm 16 and do not know much about evolution besides my high school education therefore I forewarn you I speaking of a place of ignorance. I was thinking lately that maybe human beings were naturally hard wired to weaken and die in order to maintain the population. Could this at all be possible? If not please explain, it would be interesting to find out why.

I think this will give you your answer Why do we age and is there anything we can do about it? | Understanding Genetics

Originally Posted by Deewreck

I was thinking lately that maybe human beings were naturally hard wired to weaken and die in order to maintain the population.

Evolution doesn't really work that way. Consider what evolutionary advantages there would be for a longer life. There's strong natural selection to live long enough to fully raise children; what is there much past that age. There's an interesting hypothesis that women live longer than men because there was at least some selective pressure for grandmothers to help raise their grandchildren--a group they share a quarter of their genes with.

Originally Posted by Lynx_Fox

Originally Posted by Deewreck

I was thinking lately that maybe human beings were naturally hard wired to weaken and die in order to maintain the population.

Evolution doesn't really work that way. Consider what evolutionary advantages there would be for a longer life. There's strong natural selection to live long enough to fully raise children; what is there much past that age. There's an interesting hypothesis that women live longer than men because there was at least some selective pressure for grandmothers to help raise their grandchildren--a group they share a quarter of their genes with.

That sounds like a pretty good point. I would have thought living longer with limited resources in an area to live would be a disadvantage but I guess humans and their ancestors were able to just migrate instead of having to worry about that.

Originally Posted by saurabhkumarsingh

I think this will give you your answer Why do we age and is there anything we can do about it? | Understanding Genetics

Thanks the link at least partially answered my question and taught me a thing or two.

The main way for people to die when an area is overpopulated is by transmissible disease and by starvation.

We're biological and all animals and plants survive best when they have adequate food and protection from diseases as well as environmental conditions that hurt them. It may well be that the stresses of crowding might weaken some people's immune systems leaving others to survive those conditions better. It may well be that people with more strength and energy to seek food or with a propensity to make better biological use of the nutrients they can get so they will survive better than those who can't. More crowding would also mean that epidemics can spread more easily. (Think influenza.) If the disease in question has both a high transmission rate and a high death rate, then many more people will die than might have done if they'd been able to keep away from contact with infected people

There's nothing nice or easy or elegant about natural mechanisms for reducing over-large populations.

Entropy or otherwise known as the second law of thermodynamics is the force you are looking for. Anything that is organised the universe will eventually want to randomise and average out. So as a highly complex machine we humans are fighting entropy with out bodies everyday. Turns out its the number of heartbeats that determines life spans. That is the constant amongst all animals. Mice live shorter lives because there hearts beat faster. Turtles live long lives because they have a slower heart beat and metabolism. It is well known that restricting calories can increase life span. This works because it slows your metabolism and number of times your heart beats. It also reduces free radicals that cause damage in your system.

From what I know of speciation, age is primarily a factor of the life history of a species. Certain species are able to survive in disturbance-based populations where they tend to be short-lived and breed rapidly. Stress-tolerant organisms tend to live longer lives, but their populations are slower to recover in the event of a disturbance.

You can read up on universal adaptive strategy theory if that helps. This isn't really my area of expertise, just to be clear.

The default position is early death. Most mammals do not live more than a few years. The probable reason is the accumulation of defective genes through mutation. Natural selection will not be much of a force to remove such genes if they have their main effect after the individual has reproduced. Defective genes that cause harm early in life are removed from the population before too many generations pass. Examples are progeria and hemophilia, which kill at an early age. Defective genes like that for Huntingtons disease are not removed from the population quickly, since they cause harm to individuals later in life, after reproduction.

After billions of years of evolution, the human genome is riddled with defective genes that cause harm at a greater age. Evolution does not remove these genes since there is little advantage in doing so, since those people have already reproduced.

The genes that are removed depend on the way of life of the animal concerned. Large animals, that reproduce slowly, normally live longer, because an early death will stop reproduction. Thus, natural selection removes harmful genes that kick in too early. Humans fit this category, and that is why we live so long. In fact, humans live to a much greater age than is predicted by body size alone. The extra age comes from the need to take longer to raise our offspring, since human children take so long to learn basic survival skills. As previously mentioned, since grandparents are a vital part of such teaching, evolution removes genes that cause harm to people before they become grandparents.

After billions of years of evolution, the human genome is riddled with defective genes that cause harm at a greater age

The issue I have with this statement is that we are very complex machines. Even if genes are defective they usually only account for 30% of the outcome with the other 30% being how a person is raised and 30% being environmental factors. Not everyone with the gene for Huntingtons gets it in the same way. The problem with your assumptions is that evolution is not always clean. Sometimes the fittest die and the fat survive. Studies have shown that genes change during the life of an organism as well. Some people feel that Some genes can be changed by the organism and the mutations occur not by accident but by some form of design by the animal itself. Studies have shown that what is in the other parts of the cell also play a much more significant part that what happens in the nucleus and in the genes. Maybe statistically some of what you say is true, however I don't think its that simple. We are very adaptable and malleable and our destinies are not predetermined in the womb.

Uptonryan

We are talking large numbers of genes. Over billions of years, the harmful genes that accumulate are many. No one knows just how many, but my guess is about 1,000???? If one gene fails to kill, another will.

That being the case, there is ample room for individual variation. Some people die at an earlier age due to susceptibility to heart disease or cancer. Others die later. Lots of damage is shown as people grow older. Blindness, deafness, shaky hands, mottled skin etc. All due to genes that have their impact later in life.

Any gene that causes harm early in life will be weeded out by natural selection quickly. Hemophilia (until the advent of modern medicine) was removed from the gene pool within some half dozen generations. Huntingtons chorea could last up to 50 generations, since it had its impact after the victim had already produced offspring. Only the slower maladaptive force of lack of grandparents worked to remove the Huntington's gene. The removal speed of harmful genes by natural selection depending on age of onset, is a well understood action.

You need to create a simulation like polyworld. Polyworld: Using Evolution to Design Artificial Intelligence - YouTube After you do that you will see that it is way more complex than that. Some healthy organisms sacrifice themselves for sick ones etc.

Longevity is a complex issue with many unknowns.Nobody...not one in the last couple billion people who have died with reliable birth records, has lived past 120 years...even that one life to 120 was questionable.If longevity wasn't multiple dimensional then there should be mutations among 'billions' of people that come along every so often to extend a life significantly....hasn't happened...never happened even once. A whole bunch of genes are packing it in...if one variable doesn't kill you, another one will. One mutation might arise but not good enough. We're all doomed barring some type of advanced technology coming along.

Re male/female longevity. Not only do women live longer (have value) but in less complex, more primitive the society, the gap is even greater. Once a man teaches his sons what he knows and can't keep up physically, he is of little value hunting, etc. In contrast a woman always has value in child rearing as long as there are resources to feed her...also grandma, great aunt,etc. can be surrogate mothers if mother dies which wasn't uncommon.

Fossil

Minor correction. The longest lived person was Jeanne Calment of France, who died at 122.

There are people who have been claimed to live longer, but Jeanne Calment had the documentation to prove it, and none who are claimed to have lived longer than that had those documents.

i think you have made a very good point! why do we age. and i dont need the answer of cells deteriate or the like , ive heard that before. but why cant we cange that. the answer is we can , and will one day when the population control governments cant hide it any more. we have the technology and medicine to have someone not age atall. that is easy. and i think it woudnt be too much harder for someone say 80 to be rejuvinated, skin stretcehed back to tight, hair folicles re done body rejuvinated , it is all possible but until they find a way to feed 9 billion people it wont happen. the rich would be the only ones to do it if it came on the market. they would live forever and the poor and middle class would still be born and ide as usual, probably more actually because if the rich people could live indefinatly they would have more and more kids and would wipe the non members out and have a world filled with there families lettin the kids grow to 20 then giving them the treatment. sounds sci-fi but it is all possible especially with nano tech that can go inside the human body and stop diseases and age related deteriation. you could even keep someone as a child or baby. ovisouly inifinty of sleepless nights or teenage shit is not what they would want. the only way it would work is if they said right everyone alive now can have the treatment. BUT knowone can have children now. so the population will stay exactly the same, unless people get murdered oviosuly. what we could say to the rich people is look we wont kick off against you, coz lets face it if it did come out what was happenin then the army would be on the peoples side as most army men are not rich so we could say look have ya endless life but not on theis planet. and they would go to mars and colonise that . if you want ya cure have it we dont care if your selfish bastards you just wont be doin it on this planet!!! anyway it sounds feasable what your saying but like the holygraphic universe we will prbably never know,

Graemedon

I do not know what crackpot organisation you belong to, but there is no evidence of any 'cure' for ageing. In fact, such a cure is probably well beyond us for some time to come, since the action of growing older is very complex, and probably mediated by numerous genes. To modify the action of (possibly) 1000 different genes will require a genetic technology well beyond anything we have today. After all, we cannot even determine the function of more than a tiny fraction of the 23,000 genes known to make up the human genome.

Originally Posted by skeptic

Graemedon

I do not know what crackpot organisation you belong to, but there is no evidence of any 'cure' for ageing. In fact, such a cure is probably well beyond us for some time to come, since the action of growing older is very complex, and probably mediated by numerous genes. To modify the action of (possibly) 1000 different genes will require a genetic technology well beyond anything we have today. After all, we cannot even determine the function of more than a tiny fraction of the 23,000 genes known to make up the human genome.

There's an organisation called SENS that's focusing on regenerative medicine to combat aging. The rationale is not to stop ageing occurring, that would be ridiculously complicated, but to simply repair the damage, much like replacing parts in a vintage car.

Population control (as you refer to it) does not require that ALL humans should have a particular genetic predisposition for death. I see lethal genes as a population modifying and indeed stabilizing element involving the phenomenon of balanced polymorphism. A case in point is diabetes, whose genetic component (no matter which type of diabetes) has a lethal aspect in reproductive terms. The thrifty-gene hypothesis was proposed by geneticist JV Neel back in 1962. He suggested that in times of 'plenty' these genes (of which there are certainly a large number) have an adverse survival potential, either because they simply cause(d) death (type 1 or insulin-dependent diabetes) or interfere(d) with fertility and cause(d) premature heart disease (type 2 or non-insulin-dependent diabetes). In times of food scarcity/famine he reasoned that these genes might favour survival in some way, and particularly through metabolic protection against the life-threatening consequences of famine. He advanced this concept, since in principle the phenotypic lethality of diabetes genes should have ensured that diabetes had by now died out - literally, instead of which it its prevalence is increasing at an alarming rate. From 1969 to 1973, I carried out research which provided support for this hypothesis. A strain of desert mice from the middle east developed diabetes in about 30% of animals. Our studies showed that they had a markedly reduced metabolic rate compared with unaffected weight-matched mice, which allowed them (a) to survive higher environmental temperatures and (b) to survive and maintain body weight on lower rations. We found (confirmed by other workers) that rodents from arid origins have similarly high diabetes prevalence rates under 'urbanized' conditions. In human epidemiology, we have observed parallels: that urbanized hunter-gatherer natives of hot and arid countries (in my own studies, the Australian aboriginal) have a similarly high prevalence of diabetes (20-40%) again suggesting that over a long period, the present populations might have survived because of the underlying advantageous genotype/phenotype - which had now lost its survival advantage. In that sense the undoubtedly diverse and complex diabetes-related genes may indeed ensure the maintenance of population size and thus be central to the survival of the human race in the face of it persistently biggest threat - famine.

Wisepeter...the reality is that ALL humans die within a limited time frame. Perhaps the predisposition to diabetes may be varied, but this doesn't mean that a 100 or a 1000 other genes don't have common predisposition to killing us.There will always be differences among groups due to natural selection at the local level but this doesn't preclude commonality at a macro level. 'X' percent of our DNA will be identical.

Re the biggest threat....famine. There is no consensus on this. According to Richard Leakey the biggest threat to humans in our development was disease and infection (similar to rabbits). The human race was never threatened by famine....just individuals and local populations are impacted. Species can go on for millions of years surviving millions of collapses of food supply in specific localized ecosystems. The species continues through genes in the individuals a valley, mountain range, half continent, etc. away.