Elves in fantasy are commonly depicted as having long life spans and that applies to my story as well with Elves on average living between 250 and 270 years. The question is how would this work and what evolutionary pressures would cause a group of divergent hominids to evolve into such long life spans?
Here's a previous question I've asked in the same story. What evolutionary pressures would lead to Orcs?
Note: Magic does not exist in my story.
Not everything has to be directly driven by adaptation.
Consider everyone's favourite mammal, the Naked mole-rat. They live in low oxygen, high carbon dioxide tunnels and have to deal with inconveniences like occasionally tunneling through a nest of angry ants. Result? they're extremely pain insensitive, can not only tolerate atmospheres that would kill other animals but survive there for quite a surprising length of time.
Moreover, they have a fascinating resistance to cancer, which isn't entirely understood as yet. They seem to do better at producing error-free proteins, and their cells are less prone to uncontrolled proliferation. Their ability to lower their own metabolic rates during lean times reduces oxidative damage caused by metabolism. These things all help to combine to drive a surprisingly long lifespan for such a small creature... perhaps 30 years, simply because they're resistant to a bunch of common ways for other animals to die as they age.
Now, I'm not necessarily suggesting that you make your elves like naked mole rats, because although that would be awesome and definitely buck the trend of stereotypical tolkienesque elvishness it is perhaps a bit of a long way from anything that might be called elfin (though, do contrast with the Falmer of the Elder Scrolls).
Nonetheless it does show how interesting environmental adaptations can lead to knock-on effects that are useful in themselves.
There are basically two main evolutionary drivers:
1. 'Survive long enough to have babies'.
These are the pressures that are going to have a species develop claws, run faster etc.
2. Sexual selection.
That is, even if a specimen is surviving and reproducing, within the species certain traits might be being selected for and in the long run a species develops peacock feathers, or horns that are too big etc.
So you can use these two drivers to come up with some scenarios:
eg:
But of course - you need an explanation for those 'for some reasons'.
Perhaps elvish hair grows very slowly, and it happens to be the 'peacock' trait that elves are selecting for - therefore the older and longer living elves end up being selected for. (The trait could be anything, perhaps 'telling stories of travels' is the trait being selected for, perhaps wrinkles).
An explanation for why elves might have babies at a late age - perhaps young elves are very fragile, and also elves require some very rare element to be healthy, and so a very long (decades) gestation period is advantageous, being cocooned inside the mother has she wanders the world slowly absorbing this rare element.
A slow heart rate plays a major role in life expectancy for example,
The smallest known mammal the Etruscan shrew has a heart rate of 1,500 BPM and a lifespan of 2 years.
The largest land mammal Elephants have a heart rate of 30 BPM and a lifespan of 80 years
Tortoise have a heart rate of 10 BPM and a lifespan of 180 years
Bowhead Whales have a heart rate of 8 BPM and a lifespan of 211 years
Greenland sharks have a heart rate of 5 BPM and a lifespan of 392 years
Humans, with a mean heart rate of 70 b.p.m. and a life expectancy of 80 years, are an exception to the relationship between heart rate and life expectancy shown in animals , as their life expectancy is higher than that predicted by their heart rate. It has been estimated that a decrease in heart rate from 70 to 60 b.p.m. would further increase life expectancy from 80 to 93.3 years in humans.
Studies also show that restricting food intake in mice and monkeys can increase their lifespan up to 30-45%
Other factors that influence life expectancy is a healthy immune system and a good quality life.
In order for your elves to live up to 250-270 years they must have a slow heart rate around 15-20 BPM , They would only consume a small portion of food once a day and should have a superhuman immune system free from diseases and stress.
Rather than suggesting how they would live so long, I will suggest that the answer to why they live so long falls in line with the Grandmother hypothesis. This hypothesis suggests that the reason humans live many decades after menopause is that they can still pass knowledge down to their descendants, and can still help care for children. These actions ensure that the grandmother's genes continue to propagate.
Elves are typically portrayed as incredibly knowledgable and wise, so it would make sense to have tight-knit family and community groups in which the older members continually pass on their knowledge to others. The older the grandmother lives to be (or great-grandmother, and so on and so forth), the more knowledge she will accumulate. She will also be able to provide care and assistance to increasing numbers of offspring.
At least one source suggests that having children later in life helps promote longer lifespans for women.
This could mean that being more selective about children will result in a lengthening lifespan, and could also contribute to the aspects of elves from some fantasies eventually being in decline, population wise.
They keep having babies the whole time.
Genetic fitness is determined by the number of offspring you leave. I may be the awesomest, smartest and best looking but if I leave 0 offspring I am an evolutionary dead end. Among other variables, the number of offspring one can have is limited by one's reproductive lifespan. Humans do live on after they can no longer reproduce; possibly because having grandparents without their own children confer a survival advantage to grandchildren.
Your elves, however, crank out the pups for as long as they live and plenty of them. The longer they live, the more kids and so the genes for long life are selected for by virtue of pure numbers. The older you can get the more kids you can have and so the more genes you contribute to your gene pool.
Elves altered their DNA artificially. They used artificially created viruses to change parts of their DNA with parts of DNA they extracted from other creatures. They assimilated cancer protecting parts of genome of Mole Rats Starfish Prime mentioned, they assimilated parts of genome of whales as Pierre mentioned. Also they have parts of genome from elephants (probably, its reason why they have strange shape of ears) and owls (so they have night-vision and acute hearing), and lot of other animals.
So, Elves become chimeras, results of artificial evolution, with mixed DNA from different species.
Even if they look mainly humans, they are not humans any more.
So, their longevity is not natural, they live so long not because there is natural reason for this, but because they can.
A major enemy of lifespan is DNA replication errors. Extending lifespan is about both preventing replication errors, and detecting/killing faulty cells.
Human bodies have become fairly good at that, with a variety of mechanisms to do that; and this buys us 80-100 years. Better mechanisms are possible, and the elves have them.
They breed late in their lifecycle - either driven by economy, religion or customs they are not allowed to breed until late in their life time. This gives evolutionary pressure as only those who lived for long time in relative health are given opportunity to have offspring. Make the age of breeding related to average lifespan to drive it even further.
Some famous examples of Arctic Species with extremely long lifespans are; the Green Land Shark (400 yrs), Bow Head Whale (200 years), Arctica islandica (500 years)
If you wanted to create an ultra long lived organism, having them live somewhere cold might be a good place to start. Successive rounds of evolution could then extend this life time, if for example organisms tended to reproduce later in their lifetimes instead of earlier. This is partly why Gallapagos Turtles have evolved to live so long; they can reproduce right up until the time they die.
So hopefully this is a good start for how you could create a long lived species like elves.
According to Morgan Freeman extended lifespans are a product of a hostile environment. Extending the span of mature competency gives a creature a greater chance of survival than just reproducing quickly or having an early appointment with death which gets rid of the aged when food gets scarce.
Consider: Why do humans die of old age?
There are a few aging hypotheses, which off the top of my head are:
solution: studies have shown that a restrictive diet (eating the bare minimum and even going as far to say not expending excess energy) leads to significantly longer lifespans in mice (and presumably humans and all other animals). It's much easier for me to believe that elves show great restraint in their a petites, and are not very physically active.
Telomeres in our DNA: you can google this, but long story short, we have extra DNA that gets shorter every time a cell replicates its DNA to split into two cells. If you run out of this extra, you start getting into coding DNA (presumably) causing issues with cell function which lead to programmed cell death (apoptosis)
Accumulation of mutations: random chance events cause mutations of long time periods. Look up how cancer cells form on google for more information.
And next, we get into what the other posters have addressed. Humans never really had evolutionary pressures to fix any of these problems, cause we were gettin' banged all up on by saber toothed tigers and also killing each other en masse since we found out which end of a bone club to hold. If those pressures existed, it is not unreasonable to assume that long lived humanoid species could exist. We're already pushing the limits at like 120 years old... That's pretty insane compared to 500 years ago when you had 10 babies just to have two that lived to adulthood and break even on the population of the next generation.
Anyways, for potential solutions, off the top of my head:
more antioxidants to neutralize the ROS, low apetites/not much physical activity, and long telomeres, or a DNA polymerase that can copy telomeres all the way to the end so that they do not get shorter with subsequent replications.
That's a great start!
How: Why do turtles live long ? Their metabolism is a bit slower than us and they continue to grow very slowly almost all of their life. That why elves are a bit taller than humans.
Evolutionary pressures: Their knowledge has become too complexe to handle a long time ago and the expression of it is what attract them sexually. This was the time before writing was invented by men (at least we did that). It basically takes a century for them to master their native langage properly and begin higher educations. That repetitive learning process stuck them as "child" for a hundred years, meaning it takes this amount of time for their first gametes to appear.
Biological immortality exists in the real world.
Biological immortality means that a creature's annual mortality rate does not increase with age after it reaches adulthood. Biologically immortal creatures will eventually die from accident or disease, but they never "get old." This is in contrast with humans, whose annual mortality rate keeps increasing until it becomes almost certain that the individual will die within the next year.
You have to understand where fantasy comes from and from who it comes from to understand the metaphors involved, along with knowing all world history and Biblical history helps — so buckle up and enjoy :).
Tolkien, who wrote Lord of a Rings, is usually credited for creating this fantasy world with the different traditional fantasy races, humans, elves, orcs, dwarfs and hobbits. Tolkien was very much a Catholic, meaning that his identity and his relationship with God combined with the entire old Jewish roots are what allowed him to create these great worlds of brilliant imagination. For example, the ring in LOTR represents sin, so when one is in a state of sin, or when one puts on the Ring, they (spiritually) are now very visible to the dark forces. Naturally, orcs are spawns of these dark forces, as was depicted in them spawning out of the earth in the LOTR series.
Biblically, in the time of Adam and some years after, humans were hundreds of years old; this is the time of the Oddessy and Illiad and great giant humans (cyclops, Nephilim) — all the legendary stories were true. Great warriors like Achilles danced and dominated their way around the battlefield. Then, at about the same time as The Flood, God had enough and said decided that humans will not live longer than around 120 years. God Speaks, and it happens.
Elves then are a metaphor for a race of better humans that existed in the past. Historically this was when God literally walked with Adam on the earth. This is why in LOTR, the elves are seen as never changing, never aging; they hearken back to a better time in history who also had special (magical) powers.
This is just skimming the surface of it, but you could google Catholic Analysis of LOTR. I'm sure oceans of ink have been spilled in this path we are going down, books even who can explain this much better and more accurately in all its details that I can. Enjoy and God bless.
