A lot of fictional works contain people who are well over 100 years old, some 200, some 1000s of years old. The Emperor Of Mankind for example is over 10,000 years old. Colin from Highlander is over 2000 years old.

Realistically, how would these people think and act? How would they act or think differently from ordinary young people, assuming that their physical bodies do not age (e.g remain the body of a 30-year-old)?

My guess is firstly that they would know lots of facts, but not necessarily in depth as they may not have had the time or resources to conduct research into these areas. They might have a very well developed philosophy, taking some axioms as far as you can go by pure logical reasoning. Their decisions might be more logical and they might be faster to make decisions, so that they might be more perfect Bayesians. However, given that their brains are still only human (or slightly superhuman), they would still just be boundedly rational agents. Would they be rid of all addictions and bad habits, including bad mental habits? Would they have conquered procrastination? Would they reach the limit of expertise, or somehow go beyond it?

More importantly, how would they speak, act, and make decisions? Would they sound like otherworldly beings, or just like an ordinary friendly guy who seems trustworthy and knowledgeable? Would having so many years of experience and learning give them some unique insights not available to normal humans?

EDIT: You can take Colin MacLeod from Highlander as an example. Regular human given the gift of immortality who lives through normal human history as a regular human being (not a slave but not a king either, perhaps ordinary citizen).

  • 3
    $\begingroup$ The question is a little broad. Not to bad, but it really depends a lot on the experiences that the individual went through in their long life. Were they pretty well off for a lot of it? Have they been living hand to mouth for 1000 years? Have they had family, or were they drifting from place to place never putting down roots... I think if you edit this to narrow it down just a little you'll get some better answers. $\endgroup$
    – AndyD273
    May 12, 2015 at 14:31
  • $\begingroup$ It depends very much upon their physical state of being too. I am middle aged but I got extremely sick last year and was in extremely poor physical shape for much of the year. That affected my psychology very much. As I physically improved my mode of thinking altered again. So very old vigorously healthy old people will think very differently from very sickly or weak old people. $\endgroup$
    – Jim2B
    May 12, 2015 at 15:05
  • 18
    $\begingroup$ They would be really protective of their lawns. $\endgroup$
    – KSmarts
    May 12, 2015 at 15:22
  • 2
    $\begingroup$ Actually, another pretty big question is are they the only one? Like with Highlander you have a very small number who can't get along and who have to live in secret while everyone around them gets old and dies. That would be pretty lonely. Versus a way that a majority of people are very long lived and so you could build long term relationships that span centuries. That would really alter how a person thinks and reacts to everything. $\endgroup$
    – AndyD273
    May 12, 2015 at 16:23
  • 3
    $\begingroup$ If a person is functionally immortal, I'd think the tendency to procrastinate would go WAY up. After all, you literally have FOREVER to get to it... "Never put off until tomorrow what you can put off indefinitely." $\endgroup$ May 12, 2015 at 23:43

8 Answers 8


It's difficult to say without having any first-hand knowledge of such a phenomenon, though I would imagine that a good model for a person living to the age of 600 would be to take the central differences between a child of 6 and a grown person of age 60. Why 60? Because this is a safe age to extrapolate behavior, after which, behavior might begin to suffer from the onset of old age. Since they will have the body of a 30-year-old, I assume that diseases such as alzheimer will not have an effect.

So what are the central differences between a 6-year-old and a 60-year-old? This in of itself is a difficult question to answer because it mostly depends on the individual, however I think we can agree that generally, you see the following traits in 6-year-olds that you wouldn't see in 60-year-olds:

  • Immaturity
  • Egocentric world view
  • Innocence
  • Irrationality
  • Impatience

And so logically the type of traits you'd typically see in 60-year-olds (and again, not always) would be Maturity, Accepting world view, Knowledgeable, Rationality, Patience. Therefore presumably a 600-year-old is just a more extreme version of this.

Extreme maturity - They likely wouldn't appreciate humor as we appreciate humor, and even then, they would likely find little funny, save for very sophisticated and subtle humor which might easily go over our heads. For the most part, they'd be like stereotypical tight-lipped librarians that want nothing to do with the silly things you do.

Extreme accepting world view - Little is likely to surprise them, since they've seen everything before. The ideas that they've had over the years has solidified into granite and therefore they realize that they aren't going to change ideas. And it's not without a certain irony that this also means that they've made up their minds regarding their approach to such contrasting ideas. You aren't likely going to be able to trick one into arguing with you, but if you could and assuming you were listening, it is far more likely they'd tell you something to put your own ideas into question. Their general approach to differing world views is likely going to be apathy.

Extreme knowledge - There will be little that they do not know. Although they may not have knowledge on par with an expert in the field, they will certainly have enough base knowledge to ask a question that may stumble an expert in most fields. The type of knowledge known for the fields that interest them is unfathomable, though suffice to say that they will likely learn neighboring fields at the level of expert simply because the two fields have some common ground. In other words, a 600-year-old biologist would likely be able to tell you anything you'd want to know in the areas of chemistry or zoology, at the extreme of being considered an expert in both fields, as well as quote the first chapter of Dante's Inferno by heart just because it is a hobby of his.

Extreme rationality - A 600-year-old man would be able to argue circles around you, thinking several steps ahead. This is not necessarily because he is smarter than you, but simply because he's had a lot of time to practice. Suffice to say that after you explain the rules of chess to such a man, he'd likely not lose a single match and by the third game, he'd have figured out how to beat you in 10 moves or less playing off your own strategy. This isn't to say that such a person couldn't be wrong, but his beliefs would be deeply rooted in fact that you couldn't prove him wrong without first showing that one of these facts is fundamentally wrong as well.

Extreme patience - You would not likely see a 600-year-old man show a temper. Combined with extreme rationality and you'd feel like you were talking with a living version of Spock. In fact it would be difficult to evoke a strong sense of emotion of any kind. These types of emotions would be likely limited to only friends and loved ones and only in specific occasions.

Could a 600-year-old man be immature, egocentric, innocent, irrational, impatient? Yes, absolutely. This is merely a generalization, though you likely wouldn't see 600-year-old individuals if they did show these traits, because like children, they would "grow out of it" more likely than not.

  • 1
    $\begingroup$ Reminds me a little of the Peter F Hamilton books where people go into rejuve every 50 years or so. A first life guy who's about 50 is dating a 300 year old woman (just out of rejuve, looks 20) who tells him "Listen dear, this isn't a big deal, you'll understand when you're older." $\endgroup$
    – AndyD273
    May 12, 2015 at 16:14
  • 1
    $\begingroup$ But if he knew that ACTING emotionally would obtain good results, then wouldn't he act emotionally even if he didn't feel any emotions? For example smiling and laughing along with your jokes even if he didn't find them funny, if it could be used to his advantage? $\endgroup$ May 12, 2015 at 22:40
  • 1
    $\begingroup$ @a926587934658973465 As might anyone I suppose. There is a certain mask most people put on in public which makes them smile when someone tells a joke or be courteous towards others. Some might even use emotions to manipulate others into doing what they want (psychopaths). This is something you learn as you grow up, and though I wouldn't expect it to go away, I also don't think it would get more "extreme." More likely that a person would simply get better at saying the right thing at the right moment. However that says nothing about whether or not he would use it. Depends on context. $\endgroup$
    – Neil
    May 13, 2015 at 7:34
  • $\begingroup$ this could be correct only when excluding developed mental illness $\endgroup$
    – user22398
    Jul 9, 2016 at 22:15
  • 1
    $\begingroup$ Excellent summation. I would also posit that a millennia old individual would likely be intensely self centered, but otherwise you have just described Bayaz, the millennia old "First of the Magi" from Joe Abercrombies The First Law series. $\endgroup$ Oct 31, 2017 at 10:51

Physiological considerations aside, this is what I see as the differences:

Slower Thinking / Decisions:
Old people make decisions more slowly than young people. Research indicates this is not due to cognitive decline but instead old people must sift through a greater quantity of data (life experience).

More Cautious:
Older people tend to understand the likely risks and consequences of a given course of action better than young people. They would tend to wait longer before making decisions and try to gather more information before making the decision.

More "In the Box" Thinking & Decisions:
All people rely on analogous experiences to figure out how to approach new situations. Older people will have determined certain approaches work better than others in most cases and will reuse successful approaches. In most situations this will lead to quicker better solutions than a young person can devise. However, in novel situations in which people have no analogous experiences, this approach could trap them into solutions that don't work.

More Conservative Thinking
As a general rule, old people have more to lose (family, wealth, etc.) than young people. They also have a lot of prior experience on how to preserve things. This will lead to a more conservative approach for how to deal with new situations (how do I keep from losing those things precious to me). Young people would be much less likely to take this conservative approach.

The Long View
Very old people will be better able to take the long-view. They will have a greater understanding how their decisions and thinking might affect themselves and others over much longer periods of time.

Also note that many people perfectly capable of doing this still won't. It's just that old age provides the framework which allows them to better understand these things if they choose to do so.

  • 3
    $\begingroup$ Considering that such a long lived individual might have already lost and regained it all, possibly several times over (loved ones dying off, wealth fluctuating due to external forces, and so on), maybe their worldview would no longer be as conservative. $\endgroup$
    – Oskuro
    Sep 27, 2016 at 8:14

The way people think would depend on the life stage they are.

People who are eternally young, will eternally think like young people. People who stop at "mature adult" will think like other mature adults. People who grow old, but simply never die, will think like other old people.

A person who has lived over several eras does not fundamentally differ from a person who has lived in several cultures. That is exactly what the immortal would be after all. A relatively young immortal could be modelled by an immigrant from a foreign culture. The exact issues vary with original culture so the match is not exact with any actual actual group of immigrants, but if you look at issues common to most immigrants, the immortal will have experienced them to some degree.

For older immortals you can look at groups that generally have lived in several cultures such as cultural anthropologists and retired military who have spent their lives overseas in several different locations. This depends on whether the immortals try to blend in or have their own society. Which obviously depends on how common the immortals are.

Most knowledge and training has specific context it is relevant and becomes simply a curiosity over time. Most mortal people (certainly here in world building...) have few areas of interest where they know lots of generally useless trivial. The immortal would not really be qualitatively different, but quantity and breadth would be larger. But, of course, after a certain point quantity has a quality of its own so the really ancient might be weird enough for it to matter.

The immortals might try to make their knowledge relevant by choosing fields such as archaeology, history, writing historical novels anthropology, or acting as occupation. Or they might choose areas where the practice they had centuries ago might still help such as mathematics, many forms of music, dancing or martial arts. Realistically, the immortals would have enough accumulated property to live without an actual occupation and no more trouble picking up an entirely new occupation than any other person of their apparent age.


If I knew I were immortal, I would spend most of my time trying to acquire new skills. To some extent, this is necessary just to survive. After all, whatever earned money 200 years ago is not necessarily relevant today. But it also means that the immortal would have time to learn music, art, history, and science, assuming a human brain can absorb all that knowledge. Unless the immortal had an IQ of 90, in which case they would likely live hand-to-mouth until they eventually died.

The easy route to survival is to be a mercenary and work security. Physical combat of the bar bouncer variety hasn't changed much over 600 years, so you should be employable across time quite well. An unambitious highlander might well resign himself to this rather boring fate.

A traveler might expose him/herself to all the world's cultures, even though that exposure will itself become obsolete with time. The extra time could be leveraged into a master level of diplomacy (imagine just 20 years with Rosetta Stone), or squandered on SnapChat.

It all boils down to how ambitious such really old people are. Even today, some old people go on cruises, while others watch t.v. in a retirement home. The interesting ones are the ambitious and active ones, and these would continue to gain skills until they were obviously more talented than everyone else around them. Given how often ideas are rediscovered, this person could simply appear more intelligent than everyone else simply by remembering stuff that happened hundreds of years ago.

  • $\begingroup$ An Immortal with an IQ of 90 at age 556 would be indistinguishable from an Immortal with a IQ of 100 at age 500 or an Immortal with an IQ of 110 at age 446. Such a small difference in IQ would not have much effect on the Immortal's fate, only on the exact number of elapsed years to each level of accomplishment - a number that would probably be overwhelmed by differing life circumstances anyway. - Your point still stands if you consider a more drastic mental deficiency. $\endgroup$ Jul 9, 2016 at 18:05

One possibility that has been neglected in other responses is that they simply wouldn't (at least act.) This is the route of the Antediluvian vampires in World of Darkness, and a real-world example of the psychological type (though not due to extreme age) might be the mature Cratylus of Athens, a radical student of Heraclitus of Ephesus. The mature Cratylus would not even speak, so paralyzed was he by his extremist process philosophy. Whereas Heraclitus claimed that one cannot step into the same river twice, Cratylus insisted that you cannot even do so once. The contemporary philosopher Graham Priest suggests that the mature Cratylus may be the best candidate for a real-live believer in trivialism, the view that all propositions are true. Priest claims that such a one may not take any action, because action entails a desire to make something the case, but the trivialist already believes that everything is the case. (Though, conversely, the trivialist also believes that everything is not the case, so it's really a coin toss.)

Perhaps better than having all your ancient masters be Cratylus-clones would be to give them all extreme commitments to some philosophy or another. Most of these would tend to be paralyzing or self-destructive in some way, however, so you may end up with a split class of ancient masters: the retirees who are paralyzed by their philosophies, and the actors who eschew philosophy or simply refuse to commit to a particular point of view.


Depends of his personality, if he lives forever or for very long times he might choose to enjoy the stupid phases of a human a little bit more because a person changes his attitudes depending on how many years left he thinks he has and how easily he gets tired or because he was very close to die or believes in something greater than himself

Remember that most humans care most about the pleasures of life, and some don't want to stop enjoying but time makes them to do something meaningful before they die.

Although years give you experience and experience can make you wiser, people like to have fun because its fun, imagine that it was impossible for a human to live more than 21 years, he would be very wise and giving the best of him at around 17-19. Do you think they would live with the same attitude like a 17 kid from today?

But some young people have a personality of an old person.

Sometimes personality and attitude count more to give the best of us than a skill or ability.

If Einstein had lived 500 years we can say he would be the same because he always was like that and what he did was his pleasure.

If a person who you don't like because of his actions lived forever do you think he would change his attitude at 100 years old? he might he might not.

Most of the people tend to act according the judgement of society, look at him he is 45 and still not married, that person might want to get married, but if the youngest age to marry was at 120 in a world where people lived 800 years?

more years give you more experiences for good or for bad.

How would really old people think or act?
According to his/her personality.

When I read your question, I immediately thought of Gulliver's Travels. The Struldbrugs are a race of immortals living amongst the ordinary, mortal citizens of Luggnagg. However, the issue is that they age like normal humans. Therefore,

Once the struldbrugs hit 80 years old, they have "not only all the follies and infirmities of other old men" (3.10.13), but they are also extra-opinionated and cranky because they're worried about living forever.

Their lives are really awful. Because language is constantly changing, eventually nobody can communicate with these Struldbrugs. They have no life-long friends, as who could stand another human being for all eternity? In addition, to avoid the monopolisation of the world by Strulbrugs, in Luggnagg these immortals become legally dead at the age of 80. In accordance with this law all of their property and finances are taken away at this point in their lives. In theory, it sounds vaguely reasonable, but when it is put into action, it just means that the streets are littered with incredibly ugly, incoherent and grumpy beggars.

In this universe, I think that the reality of immortality would be different. But this novel presents the idea in a very interesting manner.


This question really depends on many factors, such as when the person was born and what sort of personality they have. If the person was born around the time of the Spanish Inquisition (and supported said inquisition), they would no doubt be highly disillusioned with the rise of secularism and the separation of Church and State. Maybe they would eventually begrudgingly accept it. Maybe they would fight an eternal battle to overthrow those changes. You have a lot of room for creative freedom here.

If the person knows they are immortal, I would imagine that they would be very risk averse and patient - even when they are young. Mere mortals know they are eventually going to die, so we are all forced to come to terms with it one way or another. Immortals will not. They can also work on building their lives on extraordinarily vast timescales. Even if the best job they can do is work as a laborer, they could put aside some of their income, invest it, and over the centuries become immensely wealthy. They could defer starting a family indefinitely, as well.

Politically, they would first and foremost support ideologies that afford them greatest personal protection. If immortality is rare, I could also imagine that they could see themselves as superior to mortals and use this as the basis to create an immortal aristocracy or autocracy. Given the power and influence they would accumulate over time, class separation between immortals and morals is inevitable. That could also drive social unrest and resentment. Note that, over time, the number of immortals would steadily increase, so even if it is rare they could still exist in substantial numbers.

As for speech, the person would likely use an antiquated form of their language. However, if you have a substantial immortal upper class, it is likely that the entire evolution of the language would be influenced by this. Older phrases would remain in use for much longer, for instance. In this case their language use would be considered a standard dialect, rather than "outdated".

There are countless other scenarios we could explore here: the question is rather broad.


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .