I'm current planning a story which includes a race of diminutive humanoid aliens, one of whom crash-lands on Earth. They're fully sentient, and have the same average intelligence level as humans. The other main difference from humans, besides their height, is that their lifespans are much shorter.

Using sols (Earth years) as a comparison: an average human reaches maturity around their mid-to-late teens, and has a life expectancy of 70-80 sols. An average member of the alien species reaches maturity at around 4 sols, and has a life expectancy of about 20. 30 is almost unheard of. The crash-landing alien is therefore astonished that the first human he runs into is 36 sols old.

This raises an interesting problem. 20 years isn't an awfully long time to do anything at all. If they spend the same number of sols in education as we do, they won't have much time to do anything with that education by the time they graduate. If they spend the same proportion of their lives in education as we do, that's about 3-4 sols, which is nowhere near enough time to actually learn a whole lot.

So I imagine, compared to humanity, these relative mayflies are going to find technological progress quite difficult. It won't be so much "standing on the shoulders of giants" as "balancing precariously at the top of a chain of fifty aliens, all standing on each others' shoulders". So I ask you: could a species whose average livespan is only 20 years ever progress far enough to reach space?

You may assume the following:

  • By "reach space", I mean a program comparable to the Apollo missions - if they can get that far, I'll make the bold assumption that they will eventually reach interstellar travel.
  • Their resources, planetary environment, and desire are all sufficient for space travel.
  • Their discoveries are sufficiently documented to be remembered and built upon, as mankind's discoveries (generally) have been.
  • The aliens do not have the means to artificially extend their lifespans (be it via DNA modification, cybernetic enhancement, or whatever).
  • They do not have the assistance of other alien races who are trying to "uplift" them.

I'm aware of this question, but there, the "shorter lifespan" is that of humanity. I'm going 3-4 times shorter than that, and I want to know how far they could progress, not how fast.

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    Makes me think of the Salarians from Mass Effect. – Renan Oct 22 at 13:08
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    Define “maturity”. Is 4 alien years equivalent 18 or so human years? (As it relates to biological maturity, I mean. Like “dog years.” Is a 4 year old alien as mature as an 18 year old human?) – HopelessN00b Oct 22 at 16:17
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    There's plenty of answers already, so I'll just add a point for them to consume should they wish: Humans are extremely inefficient with their time. We baby our children until they are 18 or more, so they don't even have to take their life very seriously for the full life span of your ETs. University teaches very inefficiently, and everything you get in 4-6 years of university study could be done in 1-2 for many if it were focused and if students could go at their own pace. We are restricted by bureaucracy. We have down-time and retirement. Very little of human life is focused on advance. – Aaron Oct 22 at 17:47
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    Since you specifically mention Apollo, it's worth mentioning that a lot of the people running those missions were quite young; I haven't looked, but I am pretty sure that the average age in Mission Control was under 30 years during the Apollo missions. Certainly there were many, many, many more people involved in Apollo than just those at the MCC, but it shows that age as measured in years of life isn't an absolute limit, even in humans. – a CVn Oct 22 at 18:01
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    What makes you think that they couldn't? There's only two things you need to get to space: people who want to, and people to pay for it. @aaron - that's the only answer I'd UV. – Mazura Oct 23 at 0:03

13 Answers 13

We waste a lot of time repeating things to children without the maturity to care. Most of school maths could be taught in a year by skipping all that repetition. Most of the rules of grammar are slightly pointlessly rigid. A slightly dystopian society would allow early testing of abilities to push people directly into a specialist career rather a more general education and freedom to choose.

A few upgrades on their ability to learn and consciously recall information without needing as much repetition then they could easily compress at least our basic first 18 years education into no more than 3. Meaning they'd be 5-6 years old on completing higher education. 10 years of working life and a low tolerance for bureaucracy would even leave them with some retirement time.

If we consider the rate of technological progress during WWII, a period when certain technologies got the full focus of certain governments. Replace the 4-5 year funding cycle with something that moved fast enough for the necessary pace of their society. They would feel like they truly were standing on the shoulders of the slightly taller members of the previous generation as they went into space.

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    This. The youngest human graduate (first class honours in mathematics) at Oxford university did so aged 13, and went on to "double major" in maths and physics, with a PhD in maths, by age 17. en.wikipedia.org/wiki/Ruth_Lawrence. Humans can complete courses up to university entrance level (in the UK) by age 7. telegraph.co.uk/news/2553538/…. The aliens should have no problem with shorter timescales than those. – alephzero Oct 22 at 16:19
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    And we're teaching children, however if they were mature at 4 ... Maybe mentally stronger on average, less sleep. 15 hrs of studying as an adult while highly focused vs 4 hrs in primary school as a kid. Yep, no problem. – DonQuiKong Oct 23 at 17:13
  • All that repetition is actually pretty vital, considering that it and emotions are the only two ways we currently have to improve our long term memory. Then again, an entire species of immature, highly emotional Taskmaster (Marvel) sound like fun, and ready for any possible action sequence 😉 – Nam Nguyen Hoang Oct 24 at 18:25

Rapid evolution in a harsh climate and environment

They'd have to reach maturity quite early on, and assuming their cognitive abilities are similar to humans (same learning speed, same memory on average), most of those who can specialize in one domain will die long before they can sufficiently advance on that. Let's say maturity is reached at age 5 (equivalent to human age 20), they'd have ~15 years on average for that. For humans it takes up to a long lifetime in order to provide something innovative to society, and only the least of us are capable to even do so. If you reduce that number even more, the chances get even worse.

However, the speed of evolution for that species is strongly boosted, meaning the gene pool can adapt much faster than that of humans. The outcome could be that the average intelligence can increase a lot quicker along with other traits. Be reminded, genetic adaptation devoid of mere conditions of survival is mostly subject to reproduction - thus also a matter of societal circumstances. But, it's genetic adaptation, meaning intelligence and industriousness have to be evolutionarily preferable - or to be more precise: Females have to prefer to reproduce with males with high values in the metrics of such traits. Peacefulness (as of non-violent behavior) would be an advantage as well, given that "trust" is an extraordinarily important commodity in a society.

Naturally, environments significantly contribute to shape species' course of genes. Harsher conditions like having a wildly alternating yearly climate with a very cold season is a good requirement. Surviving such conditions requires thinking ahead in time, planning and the ability to defer gratification, all the while there are 2-3 seasons in which productivity can flourish. What could be helpful is that all the while they adapted to that environment, the climate would have to continue to become more and more harsh, which would raise the necessity for all the traits mentioned even more in order to pursue better technology to compensate. Predators, which require cooperation and modern weaponry may also be quite helpful in order to continually cull the "weak," but to also lay more emphasize to cooperation in general (you wouldn't want them to live too isolated).

At this point we are talking about a theoretical, evolutionary super-forge. But that would be necessary to counteract the disadvantages of short lifespans. The result can be that of a species way more advanced than humans themselves. However, they couldn't reach the mastery, experience and general education humans can achieve. So it's not that clear how both species would compare.

The education system

For the education system itself - there is no time to waste. A method would establish which would educate children and students in a quite narrow domains intensively without providing more than a minimum of education in other areas. Ambitions, intelligence and talents of children would be measured quite rapidly - IQ tests would solve most of that, the rest is up to any combination of choice, randomness or continuing to work in the domain of one's parents.

How education works in particular is up to you. It would be certainly different from our education systems. If governments are involved too much, well... count that in as a factor of quality degradation. But I assume it wouldn't be a monoculture for the entire species, just as humans don't have either - neither through time or space.

Conclusion

It's not easy, but if you shape the environment and culture in which they evolved over long periods of time correctly, it can become quite plausible that your species can advance technologically and reach space. I bet most of them would talk and think as fast as Ben Shapiro. But be reminded, their average IQ would have to be significantly higher than that of humans in order to compensate for their shorter lifespans, probably around 130 compared with what we have today. That said, those participating in space exploration and travel are likely those with above their average intelligence, ranging among the best in their domains of work, who are also tested to have top mental and health conditions - just as we select our astronauts.

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    great answer! I'd also like to point out that you can see a ghost of the education system you describe when humans themselves had a shorter lifespan - apprentices and the like were very common. Not until the average lifespan started to increase did we achieve a broader education as a society. – IronEagle Oct 22 at 13:52
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    "the average IQ can increase a lot quicker" No; not if you mean IQ as it's normally measured in humans, because IQ follows a standard deviation curve centered on 100. In other words, the average IQ will always, by definition be 100, with the outliers distributed around that. Intelligence can perhaps increase more quickly, but average IQ (and almost certainly also IQ distribution around the average) will remain roughly the same. – a CVn Oct 22 at 17:51
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    @αCVn - IQ compared to our current standards obviously, with Europeans being at 100. Take iq-research.info/en/average-iq-by-country as reference. It may change over time due to the nature of how IQ measurement works, but as reference it may be sufficient. I will clarify that part though. – Battle Oct 22 at 19:53

There a few places where you can gain time to do stuff in a very short life :

  • As you said, faster maturation. They are as aware at 4 than we are at twenty.
  • No mind degeneration. They die to some organ failure but their minds are very sharp to the end (so you get a full 16 years of smartness).
  • Better knowledge transmission. They could have a way (maybe biological) to transfer memory from an individual to another, or maybe they just have a better memory altogether. Memory is not intelligence, they could still make as much errors as anybody and be close minded to humans.
  • Hive minds. Each individual control several bodies that can do simultaneous tasks. A normal individual could control four or five bodies at the same. A few to produce and the rest to study (your wandering alien just happened to have lost his other bodies, bad luck)
  • They don't sleep. Their short lives are one third more productive than ours.
  • They have no fun. They just work all day and don't really need to pause that much.

If you combine two or three of these propositions, I think you can get an interesting species that would be able to evolve very fast.

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    +1 for no sleep. That probably makes more than a 1/3 boost. Assuming time for eating/recreation are constant, your work time goes from 8 hours per day to 16. Maybe they could sleep half their brain at a time like dolphins, but keep being productive with the other half? – craq Oct 22 at 21:18
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    Eliminating sleep could also have the potential to eliminate (or at least greatly reduce) the time spent re-immersing oneself in the experience of learning. Task switching is a notorious time killer, and if it can be avoided, the gains could be immense (provided there remains an alternate way to commit short-term memories to long-term, which sleep largely provides in humans). – Trevortni Oct 22 at 21:56
  • Faster maturation has other benefits too. Humans have to put a lot of effort into raising the next generation. If you assume humans start to be productive at 20 and cease being productive at 70, then typically one parent will spend 2/5 of their productive life solely raising the next generation, because it takes that long before they can be rational members of society. If alien children can be self-supporting by the age of 1 or 2 (even if they have more learning to do) then that adds a huge amount of extra resources back into society. – Graham Oct 23 at 10:45

By reaching maturity at 4 Sols this isn't actually too bad, they have 16 years of maturity per generation, which would be equivalent to all humans dying at 36.

Yes 36 isn't super-old, but it's old enough to have done significant amounts of work.

They would need to develop very efficient ways to teach and propagate knowledge from one generation to another and would most likely tend to specialize. Rather than knowing a little thing about everything they would tend to be experts in one field.

You may well see master-apprenticeship type structures form as well where ongoing work gets handed down from one scientist to another. For example a physicist may train up a number of students, then select one to be their apprentice. The two would then work together closely for ten years until the elder retired whereupon the new one would train up their own apprentice so you always have (at least) two people working on every important project.

They commonly say it takes a human ten years to master something, well that gives these aliens time to apply that mastery even if it takes them just as long as humans...

  • I'm a bit worried about a tight master-apprentice relationship taking too much time away from the most experienced individuals, especially if the students start early. Still, a lot of valid points. – Ruther Rendommeleigh Oct 23 at 9:31
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    @RutherRendommeleigh The apprentice can start helping early on in the process by doing simpler work for the master, then over time helping with harder and harder portions. Yes there would be a cost, especially early, but it's unavoidable in this situation. – Tim B Oct 23 at 14:57
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    You get the win by the better knowledge transfer, and co-operation though, sometimes all you need with a task is someone to bounce ideas off. – Ryan The Leach Oct 24 at 1:26
  • Look at medical school methods for teach surgical procedures: * Watch one * Do one * Teach one – Sherwood Botsford Oct 24 at 13:50

I think this would be do-able - it might take them a bit longer (in terms of generations certainly!) but it would be do-able, partly because I'd anticipate such a society adapting to their limitations and partly you could do some relatively minor biological/neurological tweaks.

Societal

Awareness of mortality - A race that is aware of their average lifespan can plan for what happens after an individual died - humans already do this: finding ways to efficiently record information so that the next generation aren't beginning from scratch is a good example. Once they started getting into more and more complex areas of science and thought that were taking longer than the productive lifespan to deal with I imagine they would have prioritized this aspect heavily. They are also likely to have focused heavily on time-saving technologies, perhaps sooner than we did. There are things that we developed post-Apollo that would have sped the process up (advances in computing, knowledge-sharing etc), have those developed first and the job of getting to space is much less time intensive.

Procrastination - We humans procrastinate alot, think about your average undergraduate university course (~3 years), it's really not three years of full-time work. Were it not for the cultural expectation of there being a large amount of time spent having fun at university you could do a bachelors degree in two years easily. We just have no need - because we have the time and we know it.

Biological

Increased neural plasticity - while not binary on-or-off the human brain's ability to form new new neural pathways and learn things drops significantly relatively early in our lifespan (somewhere between 20-25 years old). Keep the alien brains highly elastic until they die and they will be able to get more learning and development done.

Increased maturation rate - you've already alluded to this but I think you missed one of the key benefits, if offspring are mature in just four years that means that the parents are going to have to spend significantly less time looking after them and raising them. Freeing them to return to a more complete focus on their "work" sooner.

Increased decline rate - make the same true at the other end of the scale as well, while humans may live to 79 years on average most start to experience noticeable health decline much sooner, limiting our effectiveness in the latter stages of life (and average retirement age is between 59-70 so at least 9 years of that aren't really counted for things like, say, Apollo programs). We've managed to extend human life expectancy significantly over the last few decades (the US male average was 66 when Apollo landed us on the moon!) but we haven't solved the general issue of decline in old age. If your Huminis can remain effective and efficient up untill say a few weeks or months before death that will help.

Reduced need for sleep - humans generally need 6-8 hours out of every 24 to be healthy, if your aliens can do the same on say 1-2 hours out of 24 then over a 20 year life span they have 36,500-43,800 extra hours in that 20 years than we do that's another 4.2-5 years they are effectively getting for "free"

Smaller size = smaller travel distances - humans like a lot of personal space for living in and so on. Even if the Huminis want proportionally the same the actual physical distances are going to be much shorter, but physics doesn't really care about that - if they make a car or train that goes at 50 mph but the distance they need to commute to work is say 20 miles less than an equivilant human they are going to get there sooner. Spending less time moving from place A - place B would free up a hell of a lot of time that can be better utilised for achieving things.

Smaller size = lower mass to lift to space - The nature of the rocket equation means that a massive barrier to human spaceflight has been that we need to lift massive amounts of mass up to space (the spacecraft needs to be big enough for say 3 humans and humans are bigger = more mass, the humans need more oxygen, food, etc = more mass) and the bigger the mass you need to lift the more complex the engineering challenge is in doing so. And a simpler engineering challenge can usually be resolved in less time.

Lots of good answers here – just wanted to add something I think was missed.

For most of human history, education didn't take 18 (or 22!) years.

Up until the mid-20th century, most people learned to read at best and stopped there. The brightest were more or less able to start adding to human knowledge shortly after that. As a recovering mathematician, I can give you tons of examples of these types of folks: Gauss, Galois, Riemann, Ramanujan, Noether, Lovelace, Cauchy, Poincare... all of them made significant contributions to mathematics/physics before their 30th birthday (and some, like Gauss and Cauchy, were child geniuses). And there are tons of other examples.

So, maybe your civilization would require a longer time to get to the same point, since you might need more of those child geniuses and you'd miss out on late-life geniuses like Euler, but it could still certainly be done.

The only reason we have schooling for so long is that so much has been discovered. And this isn't even getting into all the critiques of our out-moded education system (which is based on a system that wanted to have interchangeable workers in a pre-computer society). If your civilization can avoid falling into that trap, they can get people making discoveries earlier.

Another aspect is how discoveries tended to get made 200 years ago vs. now. Something that annoyed me when learning math in school was how many different things were named after the same people, and, frankly, how simple they seemed. They had the advantage that there were so many things to discover and figuring out one kinda lead to the next.

The vast majority of the major advances can be made by people early in life; it's only once there's a ton to build on that you start having trouble. I suspect your civ will have a 'long tail' of small amounts of progress after a certain point.

  • Once they realized that their progress was limited by child geniuses, would they set up a eugenics program to breed for that? Add to that a Howard Families plan to breed for longevity. E.g. Mice normally live for 1-2 years, if not eaten. Breeding for long life has extended that to close to 5 years. – Sherwood Botsford Oct 24 at 14:01

I think the solution would be for the aliens to be have knowledge genetically encoded and passed from parents to offspring. For example, the offspring of two mathematicians might be born hard-wired for maths.

The disadvantage of such an approach is that offspring are less capable of adapting to changes in their environment during their lifetimes, but here's the thing: if you live for a very short time, the degree of change in your environment is proportionally less.

Crash landing on an alien planet would probably be traumatic for such creatures, but hey, that can be part of the plot line.

What kind of 'Intelligence'

The question specifies that the aliens have "the same average intelligence level as humans", but there are many aspects to the concept of "intelligence". I doubt there is a consensus in the scientific community regarding the full list of aspects that constitute "intelligence". And among humans, the distribution of those various aspects to individuals is wildly uneven.

Given the remarkable variation possible between one random "average human" and another, even assuming the overall "intelligence" is the same, two humans can have remarkably different aspects of intelligence. For example, one might be phenomenal at rote memorization, while the other is superb at performing mathematical calculations. All else being equal, those two individuals might be said to be of the same "average" intelligence, overall.

Now to take that concept, and transfer it to an alien species in a way that allows them to reach spacefaring technological levels without exceeding "average" intelligence, all you need to do is pick and choose which of those intelligence aspects are more common among those aliens, compared to humans.

Mathematics, engineering, logic, will be needed for the sheer ability to achieve space flight technology. Remarkably strong memory will make sure they retain any knowledge they get in their short lifespans. Creativity and imagination will need to be present, to inspire the desire to reach for the stars in the first place, but could be relatively surpressed compared to human levels, and even less artistic and abstract thinking traits to balance it out to "average".

So you have an "average" level of intelligence by improving some aspects, and reducing others. Improve the ones needed for the goals of the story, and keep them average by reducing whatever is left over.

The exact list of attributes can be decided by the needs of the story, as well as just how far imbalanced they really need to be.

It depends on their culture.

(I'm assuming they've reached a society more or less like ours (without space programs, of course)).

Guilds

They are divided in guilds that put together aliens with the same area of interest, like guild of chemistry, guild of politics, guild of art, of history, etc.

Another model of schooling

They don't spend years studying everything as we do in school, but instead, they focus on how they are going to contribute to society.

We humans divide our society by making each individual specializing on a career. The difference between us and them is that we humans spend too much time in entertainment, while they focus on their choice (groups of scientists, historians, politicians, etc). Let's say that, instead of learning math, english, science, art, history, etc, etc, etc. in school, they learn they the very basics (language?) and focus on what they need. Of course historians and politicians could lead them to disaster, but that's not the topic here.

Practical examples

  • Alien borns;
  • Spends a year learning basics (4 to 5?);
  • Starts studying, let's say, chemistry (We could put 8~10 sols here);
  • He/She joins a scientist group (Guild of Chemistry) focusing on a new project called Alienpollo Project;
  • When he/she achieves an advanced age (16?), he/she retires and starts lecturing to young aliens.

Friendship with humans?

You didn't mention if they have anything with the humans (or any other species). If this is a possibility, they can reach space.

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    The crash-landing on Earth is the first contact between them and mankind. I think I'll add into the question that there's no other race trying to "uplift" them. – F1Krazy Oct 22 at 14:38

Yes.

One of course needs a way to maintain knowledge, written, mind sharing, or otherwise.

They need to have curiosity and a desire for space travel.

Culture

One big piece that limited our progress was cultures that rejected advances because they went against an established orthodoxy, religious, scientific, etc. This still happens even today.

Many scientists were shunned or didn't publish their work due to potential backlash by 'the establishment'. Newton for example, didn't publish his work on calculus right away fearing criticism. Galileo was persecuted for his research.

If our culture allowed a free exchange of ideas without egos or orthodoxy, scientific progress would have been much quicker on Earth.

As to the short age, we've had many progeny that contributed to our advancement before the age of 20. So even if humans only had a 20 year lifetime, we still would have eventually gotten to space. If your aliens mature sooner and can learn and maintain their base knowledge I do believe it would be inevitable for them to invent the technology required for space travel.

The government or institutions would have to make it a priority and steer their gifted individuals towards that end goal. That's another big if. They might have other priorities, improving life span for example.

We're not that slow

Countless examples from e.g. music, (e-)sports, science and engineering show that a talented and motivated human child, in a suitable environment, is quite able to compete with adult professionals in a specific field, and even advance the field as a whole. This will, of course, not be possible for every child, but early exposure and a cycle of positive reinforcement can help development, and, perhaps more importantly, will allow you to identify the most gifted individuals and place them in a project that fits, and will benefit from, their abilities.

Culture plays a big role

Your education system should probably focus more on individual growth and practical experience than conformity and "one size fits all" packages. Learning and practicing a profession should go hand in hand with (and be tightly coupled to) "basics" like culture, language and math. Yes, that means that your active workers' skills will vary wildly, but it'll also lead to a higher average aptitude and a cultural know-how that will help mitigate this.

Your bus factor will, by necessity, be kept high. Being "that guy" who jumps ship and leaves behind an undocumented mess that necessitates a lengthy training period for their replacement might be a ciminal offense.

One thing that an individual of your species will lack, compared to humans, is breadth of experience. They will be very smart and intuitive about their chosen profession and whatever their society cares most about, but appear a bit clumsy and naive when it comes to things outside their area of expertise, roughly comparable to how people with Asperger's are often portrayed.

Lifespan isn't everything

While making progress at the speed we do today requires the relative luxury of having food readily available and the internet at our fingertips, a lot of humanity's advances have happened in a time where the average life expectancy was closer to 30 than to 80 (although, admittedly, mostly due to a higher child mortality rate), and mere survival was hard work. It is generally accepted that agriculture was instrumental in buying us the "leisure time" to develop into a specialist society.

You could make this easier for your aliens. In general, smaller species tend to be more calorie-efficient, so if they found an ecological niche that provides a suitable (for Earth biology: protein-rich) diet without them having to go toe to toe with larger predators, that might outweigh the lifespan disadvantage. Perhaps they are exceptionally nimble, or possess very acute senses, allowing them to traverse areas that are "off limits" to other species? Perhaps they're highly social and instinctively able to organize in much bigger groups than the small-ish tribes humans had? All of these traits also promote the development of intelligence.

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    Minor nitpick: "a lot of humanity's advances have happened in a time where the average life expectancy was closer to 30" — I really wish people would stop peddling this statistics when discussing lifespan as it's significantly offset by child mortality rates. If you survived childhood and made it to being adult enough to contribute to society, you had decent chance of living way past that. – Tamius Han Oct 23 at 12:30
  • @Tamius Han I've considered that, but making a child isn't free, biologically speaking, so I believe the statement still holds some value in the context of this question. Nonetheless, it's worth pointing out. I'll think about how to rephrase the answer. – Ruther Rendommeleigh Oct 23 at 13:48

If putting your question into grotesque maximum, it sounds like "Have mosquitoes any chance to reach outer space". However, despite its provoking influence, actual answer is "it doesn't relate to a life length".

Ability to progress as a society is more about mental development speed, not about education amount. As an example, we can take us, human race: our traditional society reached outer space, invented StackOverflow and all that cellphones; however some aborigine tribes still stick with basic skills from stone age, not more. So, the faster is a particular specimen goes through it mental development, the more chances it could positively affect next generations, by both improved genetics and shared skills.

So, final answer is "yes".

As an interesting aside, it's worth mentioning that, at certain points in history, humans have had a similar lifespan to what you're proposing.

For example, the average life expectancy from birth in classical Rome was just 25 years old, and their society helped to shape the modern world, so I don't think a short life span precludes anything you're stating in your question.

Perhaps the life expectancy of your aliens will change over time, as the environmental factors they are exposed to change (such as being on a different planet).

  • That's not how average life expectancy works. As the name suggests, and following your link to Wikipedia confirms, the "average life expectancy from birth" in classical Rome takes account of infant mortality. In other words the average is dragged down by a high proportion of babies and children dying in the first years of life. It does not mean that people in ancient Rome expected to die of old age at around 25 years old. Quoting the Wikipedia article: "But for those who survive early hazards, a life expectancy of 70 would not be uncommon." – Lostinfrance Oct 29 at 22:11
  • Average life expectancy is exactly what it says, and it does legitimately get dragged down by infant mortality and other factors, otherwise it wouldn't be an average! It is true that when you reach an older age, then your life expectancy is increased, but that is no longer an overall average. You're also forgetting other common factors of mortality, such as diseases (black death, STDs, etc), tainted food and water, dying at war, etc. There was no such thing as chlorinated water, vaccines, and medicine was a lot more primitive. You're making it sound like you only died as an infant or an OAP. – Doctor Jones Nov 2 at 9:28
  • Yes, it's entirely legitimate that infant mortality drags down average life expectancy. That is exactly why average life expectancy corresponds so poorly to lifespan. The question posed by F1Krazy asked about a species the vast majority of whom are dead of old age by 30 "sols". The experience of the ancient Romans who, to be sure, had a greater risk of dying young than we do, but whose idea of "old age" was 70+ would be completely different to that of these aliens. Certainly, the Romans did not only die as an infant or at an age of more than 70, but they could live to be more than 70. – Lostinfrance Nov 2 at 11:05

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