Is it true that the natural lifespan of humans is only 38 years old, hardcoded into our DNA, and we only live past that because of loads of modern medicines/technology?
Asking this because none of the 38 year olds I know are taking any medications and they look really young
Not at all. Until roughly 150-200 years ago infant and childhood mortality was almost 50% worldwide, which of course massively brings down the average lifespan. If someone made it to 20, they would probably make it to 60 and have a good chance of seeing 70 or more.
I feel a lot of the mortalities after 20 are things like infections. You really don't have to go too far out of your way to stub a toe and ends up with sepsis. Things we've dealt with really effectively after a cure is detected.
No. People even in the beginning of civilization lived for much longer than 38 years.
beginning of civilization
Beginning of civilization is not the natural lifespan either, even early civilization has advantages that can extend natural life.
Clearly we are already ageing at 38 years old, meaning that from an evolutionary point of view, our lives don't matter much after that point.
No. And to be honest, it's kind of stretching the limit of the title of the community.
The Bible talks about people living to like 180 years old, and we all know that everything in the Bible is fact, so...
It’s a myth that people didn’t used to live very long. Infant mortality rate brought the average way down. However, everyone in power was super young for a while after the Black Death for obvious reasons.
No
Most people in the world do not have adequate healthcare, many never seeing a doctor in their lives. Plenty of those live to much older than 38.
I'd say it's very simple to see that whatever you found there is either misrepresenting majorly or complete bollocks.
It's because the 38 years as average lifespan is skewed by high child mortality. People lived about 70 or 80 years – provided they first made it alive through childhood.
No. It’s true that our DNA degrades (loses telomere length) as we age, but that doesn’t affect us until way later in age.
Nobody dies "naturally" of old age at 38.
But genetically we come from nomadic tribes, and the nomads of a 100000 years ago, had a far shorter average lifespan than after we settled and began farming. Also people of nomadic tribes in the rain forests of South America today, often don't live longer than that on average AFAIK.
When we look at animals, it is also not uncommon that a tamed animal pet can live twice as long or more than they usually do in the wild. For humans if modern environment has similar impact compared to the harsh life as a nomadic people, the double of 38 is 76 years, and that's pretty close to life expectancy today.
So I certainly wouldn't dismiss the claim outright, but the article is a bit thin on details on the science.
But it's not just medicine (as speculated by OP), it's also hygiene, food safety and work safety, so we avoid many external factors often until our body is simply too week to continue. We basically all reach an age where we are definitely ageing, and are very far from peak condition. Strength, speed and agility wise, very few sportspeople can compete over 40 years of age, despite the advantage of experience and more years of training.
But genetically we come from nomadic tribes, and AFAIK the nomads of a 100000 years ago, had a far shorter average lifespan than after we settled and began farming.
This is mainly because of child mortality. When you get five children, of which two live to be 78 and 89 and the other three die at ages of 2, 14, and 8, your children's average lifespan is 38,2 years. Typically, you either died very young, or you lived old. And the average is, well, the average of those. Basically nobody died around the age of 38.
Tribal nomads of 100000 years ago did not live anywhere near to their 60's.
AFAIK they rarely lived beyond 30.
https://www.discovermagazine.com/what-was-the-life-expectancy-of-ancient-humans-44847
Other research reveals that the lifespan of Homo sapiens may have changed from the Middle Paleolithic to the later Upper Paleolithic, since the ratio of older to younger remains increases. The same research shows that starting about 30,000 years ago at the beginning of the Upper Paleolithic, the average lifespan began to push past 30 years.
Note that Lifespan is not the same as life expectancy:
https://my.clevelandclinic.org/health/articles/lifespan
Lifespan is the maximum length of time that a person can live
So 30000 years ago 30 years was pretty much the maximum age a person could achieve.
Life expectancy would probably have been around 15.
If by "modern" you mean anything developed in the last 10,000 years, then no. We know humans lived to roughly the same maximum ages back then as today.
If you extend that to 100,000 years, then...maybe? It's hard to say but it's plausible at least.
The fossil record is not so detailed. It's hard to estimate the age of fossils, and it's hard to draw far-reaching conclusions from the limited number of well-preserved fossils that have been discovered. Most research doesn't say anything more than "adult" or "child".
There are some techniques used to estimate more precise ages, and the estimates of the age at the time of death for fossils from the Upper Paleolithic period (12k-50k years ago) or older is rather young.
The Smithsonian Institution has this to say about "Nandy", a Neanderthal fossil from around 40,000 years ago:
scientists estimate he lived until 35–45 years of age. He would have been considered old to another Neandertal, and he would probably not have been able to survive without the care of his social group.
It's similar for early Homo Sapiens fossils. At the Dolní Věstonice site, there was a ceremonially buried woman who's estimated to be in her 40s, from about 30,000 years ago. She is thought to be one of the elders.
I'm not aware of any others that are generally believed to have been much older than that. That doesn't mean that humans couldn't or didn't survive for longer, but it was surely more rare. That doesn't really support wild claims of what's "hardcoded" or what a "natural" lifespan is. There were certainly more things that could kill you 50,000 years ago than there are today, and most of them have nothing to do with DNA and have little bearing on the maximum lifespan.
The article is written very strangely, to the point where I honestly don't know what they're trying to say. They keep referring to the "natural" lifespan but never explain what exactly they mean by that, then they slide right into talking about "maximum" lifespan.
If you ignore every time they say "maximum" and assume by "natural" they mean "general life expectancy of an adult human", then it seems fair enough. But statements like "Neanderthals and Denisovans...had a maximum lifespan of 37.8 years" are utter bullshit. I honestly think they were trying to say something completely different, but then decided "maximum" sounded cooler. Probably because of the X.
No
Why ask if you're not willing to consider answers that don't agree with your source?
Asking this because none of the 38 year olds I know are taking any medications and they look really young
The basis of science is making your own observations and drawing your own conclusions. You've done the first half, now on to the 2nd.
This article is talking about a correlation they see between the natural lifespan of animals in the wild and then applying it to humans and getting 38. Lifespan in this context is like the lifespan they give for humans currently which is 73 world wide. This is a statistical average that takes into account people dying at a few months and at 102. It does not say anything about health or that the we have some sort of genetic deathclock. What it is likely showing is when we are sorta officially getting old. When you don't heal as fast and your reflexes and such may be not at top form. and that is not necessarily 38 as its unclear how the number is derived vs methlyization. The 38 number would be for a state like animals. Before domestication, before farming, etc. And again its a stastical average and a particular animal can live much longer be it wild animal or when homo sapiens were. Honestly I could definately tell a loss of for lack of a better term lets call "youth". Basically what I had going in to 30 was gone by the end of 30 and a new normal arose. If you look at it you can sorta see how we start as babies and pretty much you get more powerful as you get older through your first third of life so about 30. Next third goes down slowly but by and large maintains decently. Last third or after 60 you get things falling off faster and its hard to maintain like before. So figure in a random fight of a 35 year old and 55 year old the 35 may have an advantage but you would be a fool to think its a slam dunk. 25 vs 65 though and yeah the 65 may win but I think some luck will be needed. Again this is assuming some sort of typical. If the old guy is the mighty atom and the young guy is some super pussy like donald trump in his prime then its a different story.
They don't define "lifestyle" at all in that article. I imagine if I had to live in a cave and fight to get anything, I'd never reach whatever the natural max lifespan was, and would doubtless die in childbirth without skilled midwifery but it's hard to imagine max being 38 when fertility for modern women lasts past 40, and we can live to 80 or 90. Are we not the same basic model?
I think every study like this should be looked at and considered as a work in progress and as information that doesn't exist in a vacuum. Also, quotes like "This matches some anthropological estimates for early modern humans." might be ones to consider, as other sources do agree that a lifespan in the 30s was at one point to be expected, but it began extending past that 30, 000 years ago. So when the original study talks about 30 as the upper end, is it looking at an age where an early hunter-gatherer type human would be unable to keep sustaining themselves with that lifestyle? Is it because they are no longer fit enough to keep hunting or is it because even if somebody else fed them that all the other circumstances would just pile on? Is the idea of DNA estimating lifespan also looking at the idea that once an organism ages to a certain point and slows down it statistically dies from predation as well? Since that is something humans as a whole have been able to get past with intelligence. I don't know exactly how that all interacts, which is why looking at a lot of data is important before declaring something.
Which also brings up the idea of an average in relation to an expected lifespan. It is a commonly known tidbit that while the average lifespan in ancient and medieval times would usually be estimated somewhere in the 30s (depending on the exact era, location, and methodology), that's an average dragged way down by infant mortality, and that people who made it out of childhood would have higher expected lifespans. I bring this up because looking at the OP linked study and then skimming a look at average lifespans might make the idea of DNA-destined-dead-by-30 a lock, when it really isn't.
Obvious advancing medicine increases the population average lifespan. A human 30,000 years ago born with diabetes probably wouldn't make it very long while one born these days with proper medication lives much longer. Does seeing the population average lifespan number go up have any relation to another individual, specific human who doesn't have any sort of chronic illness? No, so again just looking at raw population averages as just one way of looking at expected lifespan is something to keep in mind.
The conclusion is that it's an interesting study to keep as a link, and use as one piece of data if you're really interested in gathering more information.
No.
People have lived into their 80s for millenia. Average lifespan used to be shorter because of the amount of infant mortality. That is, anyone who made it out of childhood was likely to make it at least to their 60s, barring things like war and plague.
The simpler explanation is that the study is cookydooks.
Poopypoops?
That is completely wrong.
Lifespan is NOT the same as life expectancy:
https://my.clevelandclinic.org/health/articles/lifespan
https://www.discovermagazine.com/what-was-the-life-expectancy-of-ancient-humans-44847
So 30000 years ago 30 years was pretty much the maximum age a person could achieve. Life expectancy would probably have been more around 15.
Read my other comment, the study is probably pretty close to the truth.
https://lemmy.world/comment/19682894
According to the article it's not about life expectancy, but that the lifespan of 38 is hardcoded into our DNA/Telomeres
Unless I missed something, the word “telomere” doesn’t occur in the article or its source paper—rather, it discusses the rate of DNA methylation.
IMO, the key passage in the paper is this:
I suspect that the methylation rate is actually tracking the end of the reproductive stage of the lifecycle, rather than the entire lifespan—it’s just that humans have an unusually long post-reproductive stage.
I'm not sure what the difference between "lifespan" and "expectancy" is other than semantics, given the context of your questions. Regardless of what our DNA says, our life expectancy is typically in the 70s or 80s, and that hasn't changed much throughout known human history, so it has nothing to do with modern technology.