I’m working on a first contact story set in the near future where an advanced alien species arrives at Earth and reveals itself to humanity, but is utterly baffled by the diversity of life that it finds on Earth.

What kind of world and evolutionary development history could possibly lead to an advanced alien species that was not aware of evolution?

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    $\begingroup$ What exactly do you mean when you say "evolution" because I don't think that makes sense only you mean a process of selecting some creatures over others in a slow, natural process? What does it have to do with diversity? How detailed do you want to get btw? Down to biomoleular mechanisms or what? $\endgroup$ – Raditz_35 Dec 22 '19 at 18:03
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    $\begingroup$ An artificial one where the aliens are dumped there haphazardly along with all the other invented species regardless of compatibility. They’d struggle to find terrestrial analogues and lack of fossil records would lead to endless ecological miasma. $\endgroup$ – Darius Arcturus Dec 22 '19 at 18:06
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    $\begingroup$ Good answer! And in such a world different species wouldn’t even share common cellular mechanics, chemistry, or genetic machinery. $\endgroup$ – Jim Dec 22 '19 at 18:12
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    $\begingroup$ Evolution is just a theory... $\endgroup$ – user6760 Dec 23 '19 at 3:32
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    $\begingroup$ Just for clarity I mean Evolution by natural selection as originally proposed by Charles Darwin and subsequently developed by many others. @user6760 gravity is also just a theory as is atomic theory that’s what science is. What is at issue is not preventing evolution from having occurred, but in preventing an advanced alien species from realising their origins. $\endgroup$ – Slarty Dec 23 '19 at 22:22

19 Answers 19


The aliens are actually intelligently designed.

The aliens and all life forms they are familiar with are designed by super beings. There are actually factions of super beings who design life forms for sport, artistic expression and other motives less comprehensible to lesser beings. Life forms are taken back, redesigned, new models rolled out and so on. The arriving aliens are the products of one such faction and know this to be the case.

The individual aliens are not members of a race as such; they are each custom products or the products of an assembly line and the notion of two of them getting together and reproducing themselves is outlandish and fanciful - like the idea of a moped and a leaf blower together somehow producing additional individuals. Individuals might be able to bud or reproduce copies of themselves but the idea of deviating from the plan for random reasons would seem a risky waste of resources.

Familiar only with such a system, the arriving aliens would interpret earth life to be the product of a similar system. They would be amazed by the combination of genius, idiocy and tolerance for inefficiency on the part of the factions responsible for Earth life.

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    $\begingroup$ This isn't as far-fetched as it seems. $\endgroup$ – dotancohen Dec 23 '19 at 5:52
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    $\begingroup$ The nice thing about this answer is it opens up further story arcs, like the aliens wondering what will happen if their Supreme Beings stop rolling out updates, and the inevitable debate about whether that's what happened on earth: the sort of thing that Terry Pratchett, Larry Niven, Douglas Adams, and C.S. Lewis could equally have written about (from different angles). $\endgroup$ – Chronocidal Dec 23 '19 at 9:23
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    $\begingroup$ @Chronocidal, or the Uplift series by David Brin, where a whole galactic empire is composed of different species who had been "uplifted" by some other species. Prestige and social standing for a species depending largely on what other species had uplifted them and their proximity to the original uplifters. Until they found humans who had not only somehow become intelligent on their own, but also uplifted 2 species themselves (chimps and dolphins) by the time setting of the books. $\endgroup$ – Seth R Dec 23 '19 at 15:06
  • $\begingroup$ @SethR the Uplift series doesn't exclude evolution though. It specifically includes management of planetary systems over geological timescales so that pre-sentient life ready for uplift can evolve. $\endgroup$ – Jontia Dec 23 '19 at 19:52
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    $\begingroup$ @Jontia, it doesn't exclude it entirely, but in Uplift no species in the galactic civilization becomes sentient without explicit intervention from another species...until they meet humans, who they are surprised to find did on their own. Humans are an anomaly. Maybe it doesn't entirely fit OP's scenario, but Willk's answer just reminded me of it and I thought OP could still draw inspiration from it. $\endgroup$ – Seth R Dec 23 '19 at 20:20

Interesting question...

The easiest answer is that, much like the invention of guns & explosives, the discovery of evolution is not inevitable. It took humans until the 1800's to really pin down a solid theory, so it's conceivable that this alien culture just happened to perfect space travel before discovering evolution.

The problem with that idea is that the invention of space travel and the discovery of evolution both have the same root cause: a society that values discovery, progress, science and exploration. If you want to get into space, you need a highly STEM-advanced civilization, and that makes it very likely that you'll find out about evolution just as a side-note.

Religious creationism - on its own - can't top this. The theory of evolution would have been discovered and accepted by the scientific community, assuming the world these people come from is enough like our own, and even if religion tries to stamp it out as heresy, they're still aware of the concept.

Oh, and as to the idea that they don't know about evolution because they're robots? No. Artificial intelligence is still subject to natural selection, so they would have diversity of what stands for life, it would just be intelligently designed for optimization as opposed to gradually culled for adequacy. Even if you can argue that's not the case, it's kind of a lazy explanation.

But there is a way for life as we know it to have space travel without the theory of descent from common ancestry:

The alien civilization is post-apocalyptic.

Let's say that these aliens, much like in real history, started to develop guns and explosives before the scientific age. They would have basic rockets and be familiar with the concept of attaching a payload, because they can make better weapons that way.

Then calamity struck. Their planet had a dust-ring that started to collapse because of the gravity of a passing planetoid or falling moon, which will itself eventually impact the planet. In the meantime, the surface is pelted with life-threatening impactors from the dust ring.

This impending doom necessitated mass exodus to the planet's habitable moon through the construction of basic rockets, like the ones that took humans to Earth's moon, but on a much larger scale.

The moon is habitable, but has no native life, and by the time the rocks have stopped falling, the main planet is uninhabitable. The moon-men, their livestock, and their crops are the only living things in their world, all of which are greatly genetically diverged from each other. From this small sample size of maybe dozens of species, it's hard to come to the conclusion that they are all descended from common stock, and there's not much reason to go back to the hellscape that was once their ancestral home.

Throughout that whole ordeal, the 'aliens' had no collective time or interest in biodiversity aside from the bare minimum they needed to set up a survivable colony, and that's an exercise in agriculture more than science.

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    $\begingroup$ It's highly unlikely that a habitable moon exist around a planet with life, without having life itself. Microbes do quite well to survive short time in space, and thus would've seeded the moon. (And only a single microbe might be needed for a moon). Also the only way the moon can be habitable is if it's near equal mass to the planet (to retain atmosphere and temperature), which would tidely lock the system and making life impossible again. $\endgroup$ – paul23 Dec 23 '19 at 23:11
  • $\begingroup$ @paul23 Nearest planet in the star system then, or space habitat, whatever. The point is almost everything dies except for the exodus organisms. $\endgroup$ – Maddock Emerson Dec 24 '19 at 17:05
  • $\begingroup$ Well that has exactly the same problem, if a planet is habitable and space is near enough that it can be survivable with semi high level technology, it is easily survivable by microbes on a comet. There's a lot of theoretical calculations that Mars and Venus in the past have shared a life "pool" with earth. Microbes can much more easily survive space than we can right now. So the society should be much more advanced in technology, and travel a larger distance (like post Jupiter, 10+ of years of travel), so that the chance of life seeding there is abysmal small. $\endgroup$ – paul23 Dec 26 '19 at 12:25

Generation Ship with a Hard Drive Failure

A single ship arrives at Earth, with aliens that have been traveling the galaxy for 1,000+ years. During this time they lost or salvaged many non-essential parts including data archives.

The ship itself would have a very limited amount of life forms, each located in an environment perfectly suited for habitation with almost no competition from other species. Likely only the aliens, a carefully selected group of plants, bacteria, and perhaps a lab grown meat organism.

The lack of similar species to compare common ancestry to (e.g. there is exactly one species of mammal, the aliens) would make rediscovery difficult. It may happen in the bacteria state, (assuming they don't live in a sterile environment), but it would be difficult to extrapolate this into development into complex species, as there would be no intermediate species with which to compare it.

If the aliens came from 2 or more species that evolved on separate planets, then skeptics could easily deride evolution by pointing to the lack of common ancestry between the species present. A genetically engineered meat creature would also contradict this theory, as it's existence would be impossible outside the lab, thus could not evolve.

Basically, living in an environment that was obviously created for them, with no intermediary links or similar species, and a few counter examples that evolution couldn't explain makes discovery of evolution unlikely. There are just too many bad and missing data points to detect the larger pattern.

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    $\begingroup$ Golgafrinchan Ark Fleet Ship B $\endgroup$ – Separatrix Dec 23 '19 at 11:25
  • $\begingroup$ this would work, of course they would be ignorant of a LOT of things, like how to live on a planets surface. . $\endgroup$ – John Dec 25 '19 at 2:34

It is possible that an advanced alien civilization "terraformed" a planet to make it habitable for them, which involved making various geological alternations, changing the atmosphere and hydrosphere, and importing various plants, animals, bacteria, etc., and seeding them on the planet.

And when the planet's biosphere was ready they sent settlers there.

Sometime later, possibly thousands of years, civilization might have fallen on both the home planet of the aliens and this colony planet, as well as any other colony planets they might have had, perhaps in a war.

But some of the settlers on the terraformed planet survived. And enough of the other lifeforms to support them. Possibly the aliens had seeded the planet with only a few lifeforms, which had been genetically engineered to supply all the needs of the colonists, instead of the thousands of species that would be necessary for a balanced ecology on Earth.

And after thousands of years the colonists might slowly develop an advanced civilization on their planet. And their geology would discover no fossil lifeforms more than a few thousand years old, and all the fossil lifeforms would be very similar to the present lifeforms since there had not been much time for evolution.

So the aliens might conclude that their planet was ten million years old, or a hundred million, or a billion, but that all life had suddenly appeared on that planet ten thousand years ago, when their myths claimed that the gods created all life. Therefor the aliens would conclude that all the present lifeforms had been created by the gods with their present forms a few thousand years earlier, just as their myths said.

And possibly the aliens might come from a gigantic planet sized artificial space habitat which had been built by some advanced civilization and maybe it was a sterile environment with no other lifeforms and food, water, air, and all other necessities were synthesized by machines and the aliens maintained those machines.

And possibly the aliens had lost contact with their mother civilization and over thousands of years had lost all records of what the mother civilization that lived on a planet was like and no longer knew that their ancestors had lived on a planet with other lifeforms or that species on a planet evolved.

  • $\begingroup$ This in concept is eerily similar to the answer I just posted, but I threw a giant death-rock at them as the explanation. $\endgroup$ – Maddock Emerson Dec 22 '19 at 18:58

How alien can these aliens be?

Much of the diversity of terrestrial life comes from the diversity of terrain. Our planet has geological features that separate living populations. What might happen on, say, a gas giant or a water world, someplace where there are no boundaries within the habitable zone. Perhaps, with only one niche to fill, only macroscopic creature was successful. If that first macroscopic success were a colonial creature, there might exist only one genetic individual that can re-arrange bits of itself.


World which does not give chance to learn it's past
Let's imagine world which does not preserve remains of flora and fauna, something like molten world. We have coal and oil because dead plants and animals weren't eaten away by specialize microbes which didn't existed back then, so give our world such bacteria from start, and chance for finding any remains would go down.

Low biodiversity
Maybe our alien friend evolved just after mass extinction. Thing that helped us to get idea of evolution was many similarities between different species, so we can assume that lower biodiversity would hinder any science in that direction.

Mindset / religion / ideology
Religions and idelogies really like to have own origin of given population. If aliens are quite fanatic in one of them that prohibits research in that field or teach anything but their own ideas (such as creationism), its possible that at least for majority population evolution would be something new.

Not much time for study
That could go in two ways; one is because of apocalyptic world, they had little time to study such irrelevant things to their survival; second they leaved world as early as they could and didn't go back, leaving only one place in universe where they could learn about evolution (given they didn't find life anywhere else.

They are robots
Maybe that's alien are all robots, for example von Neumann probes that become self-aware. If so they could never meet any life to study evolution.

For best results mix all/some of above, it should give you enough reason why they are so shocked

  • $\begingroup$ evolution does not need fossils to be discovered, and a mass extinction still leaves a tremendous amount of biodiversity, a species capable of advanced space travel will have to have gotten past the hangups or religion, evolution is pretty unavoidable if their technology has the reached the point they can leave their world., detailed knowledge of biology is necessary to surive in space. The robot one is the only one that works. $\endgroup$ – John Dec 25 '19 at 2:12

Brain fever

Issac Asimov in the Foundation Series (and related books in the same fictional universe) used the device of "brain fever" to prevent certain scientific advances from being made.

This nano-bio-tech tool infected almost all smart people much the way that almost everyone gets the common cold, and had the effect of making them dread or be uncomfortable with, or dislike, any of the scientific methodologies needed to make the scientific breakthroughs in question.

Brain fever his his books weren't precisely designed to prevent the discovery of evolution, but the body of knowledge it prevented scientific advancement in was very strongly analogous.

  • $\begingroup$ I don't remember that in the first three books. $\endgroup$ – RonJohn Dec 24 '19 at 23:30
  • $\begingroup$ the issue with this is they aren't going to invent space travel if their technology is this retarded, you need a pretty solid understanding of biology to survive long term in space. $\endgroup$ – John Dec 25 '19 at 2:42
  • $\begingroup$ @RonJohn. it's in Foundation_and_Chaos $\endgroup$ – Jasen Dec 25 '19 at 8:57
  • $\begingroup$ @John That issue is intrinsic to the question. You can't really have a solid understanding of biology without evolution. $\endgroup$ – ohwilleke Dec 26 '19 at 19:05

Post-apocalyptic recovery in a colony world. The planet had no meaningful life (it might have had rudimentary stuff that couldn't compete) and various useful organisms were dropped on it, then the colonists themselves. The initial seeding was long enough ago that survival as a hunter-gatherer was possible--then an undetected volcano sent a blast wave across the colony site (which did a lot of damage to things like vehicles that were exposed to it) followed by a lava flow. The survivors made for the hills, the lava inundated the colony site.

All technology other than what was on their persons is gone, the needs of survival and the small number of individuals mean no detailed information is passed on, you'll end up with a creation myth something like Noah's Ark and that's about it.

Once they discover anatomy they'll see similarities between the various creatures and once they discover genetics they'll find considerable similarities there, also--because that's simply how to do things, why reinvent the wheel? With no family tree to examine, however, there's almost nothing to show how this came about. There's nothing about from before the creation incident, even if someone invents the theory of evolution the planet will be too young for that and it will go to the scrapheap of theories that couldn't face the real world.

  • $\begingroup$ even then they will discover the evolution of disease as their agricultural and medical technology advances. $\endgroup$ – John Dec 25 '19 at 2:19
  • $\begingroup$ @John You're assuming they brought disease with them. Also, even if they see changes in microflora that doesn't show them the incredible variety opened up by sexual reproduction. $\endgroup$ – Loren Pechtel Dec 25 '19 at 2:26
  • $\begingroup$ Evolution is even easier to observe without sexual reproduction, disease is hard to get around, mutations in our own gut flora can lead to diseases. and evolution is easy to observe in crops and microbes. This is certainly possible that is why I upvoted it, but it is an uphill battle to make it believable. $\endgroup$ – John Dec 25 '19 at 2:32
  • $\begingroup$ @John What I'm saying is what they see at the micro level won't look capable of creating what they see at the macro level. While we know the creationist arguments about microevolution vs macroevolution are bunk they will have no reason to see this. $\endgroup$ – Loren Pechtel Dec 25 '19 at 2:38
  • $\begingroup$ except their crops will also evolve, so they know it works on the macro level. $\endgroup$ – John Dec 25 '19 at 2:39

What kind of world and evolutionary development history could possibly lead to an advanced alien species that was not aware of evolution?

In our world we were ignorant of evolution until Charles Darwin theorized it in the XIX century. Until that moment all our holy books told us that all the species were created by a divinity in a more or less fanciful way.

Therefore as long as you give strong religions to this aliens, they might very well ignore evolution.

  • $\begingroup$ True, but would such a species have ever invented space travel enough to be in a first-contact situation? You need a lot of science to achieve that. $\endgroup$ – SRM Dec 22 '19 at 22:02
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    $\begingroup$ Medicine, physics, mathematics, electronic, software engineers, chemistry, etc. all have competent practitioners who believe in creation and/or intelligent design. And we made quite a bit of technical progress before Darwin. So I don’t think having “a lot of science” guarantees having a theory of evolution. $\endgroup$ – WGroleau Dec 23 '19 at 6:49
  • $\begingroup$ @SRM-ReinstateMonica There was "a lot of science" before Darwin, and Darwin did absolutely nothing to assist space travel. The one has nothing to do with the other. In short, to answer your comment-question: yes, such a species would have invented their space travel all the same. $\endgroup$ – Loduwijk Dec 23 '19 at 16:38
  • $\begingroup$ @LDutch "we were ignorant of evolution until Darwin" That is an odd way of putting it. You might want to alter that a bit since evolution was a thing many people believed in long before Darwin's grandparents were born. The simplest and most straightforward edit might be "In our world we did not develop our modern theories of evolution until Charles Darwin..." $\endgroup$ – Loduwijk Dec 23 '19 at 16:42
  • $\begingroup$ @Loduwijk citation please. My history of science course discussed just how completely unexpected Darwin’s theory was. I don’t know of anyone in Europe proposing anything like it. Maybe you have citations in China or Japan? $\endgroup$ – SRM Dec 23 '19 at 22:51

Change of the environment forces change on the organisms that live there.

An environment that became incredibly stable after intelligent life evolved could make evolution so slow that it's hard to notice even on geological timescales. Basically "it's been like this for as long as we exist, we never thought to study".

How can it be? Maybe they live in planet with no seasons and no tectonic activity and all ecosystems being self contained.

Maybe they built a Dyson sphere and it's been there for so long the knowledge got forgotten, until their first encounter with alien life on Earth.


Forced to space travel from a young age...

The Alien could have come from a planet that is in tatters. In the sense that their species is the last remaining on its planet, I imagine due to them destroying it like humans are doing to Earth. They leave said planet to find fresh land. One of these aliens is a child / baby. Who never saw the diversity of life on his own planet and hasn't been taught evolutionary science as his education has been based on maths, physics and mechanics (things that will help you survive on a space ship). They could have maybe mentioned different species but there is only so much can explain without seeing it for yourself.

  • $\begingroup$ if they had the technology to get into space they understood evolution, and if they lost it they died in space due to crop failure and disease. $\endgroup$ – John Dec 29 '19 at 14:23

There is basically only one way that is easy to believe, and it requires several contingencies.

1. they are not biological.

2. they have never seen biological life before.

If the aliens are not biological and records of their original biological progenitors have not survived, AND they have never encounters a planet with life before. Then they might not know about evolution, even then it is only an maybe. if they ever built simple self replicating machines they will discover it.

Evolution is just too central to understanding biology, if their biotechnology is advanced enough to survive in space they know about evolution, so the only solution is they have no biotechnology. They will know about how something similar can happen in computer code but they may never have connected to the physical world.


I cannot conceive of a group of natural beings scientifically advanced enough to develop interstellar travel without discovering evolutionary principles. However, perhaps there beings aren't totally natural.

Imagine sufficiently advanced genetic engineering that could create beings that could not mutate all. For example, their genetic material could be extremely redundant. Or their could be a lot of self-correction at the cellular level. Or their genetic molecules (DNA) could be so fragile that any mutation destroys it.

I would design it so that there is sufficient difference between individuals 5o appear natural.

However, unless the other macro fauna and flora were also so constructed, they would see evidence of evolution. Likewise, the microorganisms.

Even if there evidence of microscopic evolution, not seeing it in the macro world might hide its significance.


It is very simple. Evolution is the product of different form of species facing different environnement. If your alien specy is on a planet with one type of environnement, it has never had an evolution so it could not know the laws of evolution, which are still valid for these species but does not apply on a concrete situation.

  • $\begingroup$ A planet with only one type of environment is less believable than a species that does not understand evolution. $\endgroup$ – John Dec 26 '19 at 0:12
  • $\begingroup$ @John It might be for example a planet with only one, small piece of lanc and a great sea. No differences of climate on the small piece of land, and big on the sea but the currents are levelling it between the different parts of the sea. Or the alien specie has no knowledge of what is in the sea $\endgroup$ – totalMongot Dec 26 '19 at 11:54
  • $\begingroup$ Even an island will have different environments, the sea will have many environments and the idea that they would not have explored the sea but are traveling to other planets makes no sense.especially given they need to harvest enough resources ot build advanced technology. $\endgroup$ – John Dec 26 '19 at 15:19
  • $\begingroup$ @John Really no sense? Did you ever think about how far human being explored sea before going to the space? $\endgroup$ – totalMongot Dec 26 '19 at 16:33
  • $\begingroup$ We explored hte sea quite a lot, there is one portion of the sea we have not explored well but we had explored everything from coral reefs to deep sea volcanoes to mangrove swamps, millions of published papers, and as I said they have to be exploring the ocean MORE than we did because they need resources to get into space. And again unless to island is too small to support advanced technology or large animals it will have many different environments. also evolution is alro the product of species competing with each other a variety of enviroments is not nessisary. $\endgroup$ – John Dec 26 '19 at 18:11

High bio-diversity means lots of ways to stay alive.

Perhaps the alien species is one of very few to be able to withstand the environment on their home world. It's not to say their form is the only one. They might know, say, 100 species, which still is a tiny fraction of what we have on earth.

Earth's species' diversity came from lots of changes to which the life adapted in various ways, resulting in further-growing diversity. The aliens' home planet might not have had a floating continent structure, they might still live on their 'Pangea'. The axis of their planet might not be skewed from the usual 90 degrees, resulting in no seasons, only day/night intervals. Maybe the planet has thin enough atmosphere so that it is often 'wiped' by asteroids, forcing life to dwell underground, resulting in similar phenotypes even with different genotypes.


I'd like to, actually, change my answer.

I think a highly-developed civilisation is bound to have looked at least as far inside as it looks outside. I mean if they'd reach Earth, they must have had discovered means to look into themselves at sub-cellular level, to discover DNA and hence -gene mutations providing evolution. UNLESS they don't have DNA. It is the foundation of each and every life form on Earth, but we don't know if it's the only way to create life and consciousness. Life potentially might be non-carbon-based. With no DNA, it would probably work differently. Maybe even with no reproducing method. Maybe each of them would just spawn on their own and live for thousands of years adapting themselves rather than evolving as a species, since there wouldn't be any.

  • $\begingroup$ one of the creatures I have designed for my world is a water computer which naturally came about from a complex river system. it can manipulate its own "body" adapt deliberately. if there wasn't biological life on its planet it would have no idea. what evolution was. $\endgroup$ – meaninglessname Jan 20 '20 at 7:18

Honestly, something like Europe on a planetary scale. Part of the reason that nobody really came up with a solid idea for evolution via natural selection until the 18th century is that Europe's biodiversity is really, really low compared to other continents, even other mostly temperate continents like North America and Asia, largely due to the continent having been nearly sterilized by the last ice age. The continent's geography makes it easy for species to get trapped and wiped out by climate change. This is especially true for fishes, amphibians, and the like, which show low diversity outside of eastern Europe. The British Isles completely lack native land turtles, for example, which sounds like madness to anyone who lives near freshwater ecosystems. There is also only a single species of catfish across most of Europe (except Greece), despite catfishes otherwise being the most diverse group of freshwater fish in the world.

As a result it wasn't until the 18th century when European powers were setting up colonies and trade routes everywhere that Western science began exposed to the massive amounts of biodiversity elsewhere, especially in the tropics. It's not a coincidence that many of the early evolutionary theorists did work in the Amazon or Indonesia. If modern scientific practices started anywhere else it's possible evolution would have been discovered much sooner because high biodiversity would have been easily accessible.

It's also been suggested that it took humanity longer than would have been expected to develop evolutionary theory because we are virtually the only member of our lineage left alive. There is a very large morphological gap separating us from our nearest relatives (chimpanzees and bonobos), and our bipedal posture and hairlessness makes us look more different from them than we actually are. If other clearly distinct human species like one of the Paranthropus species had survived to the present day, humans would struggle to explain a species which is clearly similar to us but is clearly not us in a way that something like a Neanderthal isn't. This is the case for most species on Earth, who have many close relatives that look similar but are clearly different.

  • $\begingroup$ Yet it was a western European who first discovered evolution. $\endgroup$ – Slarty Jan 20 '20 at 8:20
  • $\begingroup$ Right, but it was an 18th century European who travelled to a number of far-off locations with higher biodiversity. Not a 16th century one who never left Europe. Most of the other contributing thinkers did the same (Alfred Russell Wallace came up with similar ideas while working as an insect collector in southeast Asia). If there was no option to do that evolution would probably be harder to figure out. Not impossible, I agree it would be hard for them to never figure it out, but it's at least more likely for people to miss it. $\endgroup$ – user2352714 Jan 20 '20 at 16:56

Love @user2352714 answer but why wasn't Darwin an ancient chinese, indian or mid eastern scholar instead ? Someone could have wondered why there were so many different types of bamboo for example instead of darwin's finches

Earth life has only moderate "size plasticity" but high speciation.

Consider a world with lower speciation and higher size plasticity. Pine trees can survive in diverse environments but size plasticity could also have adapted them to fill the niche of bushes and perhaps even grasses. Move the "pine trees" between environments and they (if favourable) or their offspring would adapt by size. Alien camels could switch to alpaca or llama depending on conditions during gestation rather than permanently differentiating.

If the alien's Darwin couldn't note the variations in species, would evolution have been discovered?

This could have far reaching consequences beyond evolution theory and their genetics would either be quite resistant to mutation or extremely fragile (so mutations fail).

A final thought - The local advantages of (earth style) speciation would probably be outweighed by the broad range survivability of size plasticity in rapidly fluctuating environments. Some bug lifeforms are already single generation size plastic dropping higher numbers of smaller sized offspring in high competition situations.


No fossil record

The fact that we have a fossil record on Earth is due to a number of quirks in Terran biology. The vast majority of easily-identified fossils are bones or shells, generally made of calcium carbonate - if the aliens' planet never developed the biology for hard body parts, chances are they would never find fossils, at least not fossils they could easily identify as the remains of long-dead animals.

Even if they do have bones, some other quality of their planet's ecology could make fossilization less likely. The existence of tar pits, responsible for a lot of fossils, are due to a peculiar quirk in Earth's history where trees developed wood before fungus evolved to digest it; remove this and there are no tar pits. Ubiquitous insects that eat bones (they might find the remains of these insects, but if they haven't changed much over millions of years that wouldn't serve as evidence for evolution).

Other kinds of fossils exist, but few are as obvious as ancient skeletons, and if we never found those skeletons, we might have come up with alternate theories for the sources of other fossils than the remains of long-dead life forms.

A recent mass extincion

Life on our planet is extremely diverse, with many living groups of organisms and many related species. It is easy to see the similarities between different life forms, and how they might all belong to families or classes. But if a recent (before the evolution of the aliens' sapience) mass extinction severely reduced biodiversity, leaving only a few examples of each class, that might be less obvious.

  • $\begingroup$ fossils are not necessary to discover evolution, also there are things that eat shells and bones on earth, fossils are the result of very unlikely events that prevent access to them. Life on our planet has gone through a recent mass extinction and we still discovered it. mass extinctions still leave a huge amount of diversity. $\endgroup$ – John Dec 25 '19 at 2:14
  • $\begingroup$ @John Up until relatively recent history, the standard consensus among the scientific community was that the universe had always been more-or-less the same as it is now (assumed that natural cycles would always bring life back to the same state it was before). Early evolutionary theorists were inspired by the fact that many living organisms are similar in form, though steady-statists had explanations for this as well, and the uncovering of the fossil record was the main source of provable data that brought evolution out from being a fringe theory into a mainstream one. $\endgroup$ – IndigoFenix Dec 29 '19 at 8:08
  • $\begingroup$ main source is an overstatement, geology showed he age of the world, and evolution was demonstrated using every thing from livestock to anatomy, ro species distribution when it was first proposed. fossils where a big help, but hardly vital. $\endgroup$ – John Dec 29 '19 at 14:18

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