5
$\begingroup$

How to have humans evolve the same on multiple planets

In my fantasy universe, almost all sentient life, and most non-sentient life including humans, was teleported to hundreds of planets after a magiclysm (catastrophe caused by extreme amounts of magic stored in one place.) Although it's not the main setting, Earth exists, and I'd like humans to have evolved there, roughly 500,000 years ago. (Which is when they were teleported there)

How can I have humans be the same (or at least very similar) anatomically on all planets while still allowing for evolution?

Notes:

  • Magic exists, but shouldn't be used to answer the question since Earth has no magic
  • All the planets are roughly similar; Earth-like gravity, day/night cycle, and ecology, although some worlds vary slightly in the ecological aspect.
  • All of the stars are sun-like yellow dwarf stars
  • Technology levels are unimportant for this question, I just care about anatomy
  • Assume something is Earth-like if you need to know something not listed, unless changing it will help justify the similar evolutions.
$\endgroup$
5
  • 1
    $\begingroup$ how long ago were they transported? 500,000 years? $\endgroup$
    – Kilisi
    Oct 19, 2021 at 20:26
  • 1
    $\begingroup$ @Kilisi it says in the question, 500,000 years. $\endgroup$ Oct 19, 2021 at 20:29
  • $\begingroup$ How similar in anatomy are we talking? Archaic humans have looked humanoid for millions of years. It's unlikely you'd go from Homo erectus (our closest relative 500k years ago, there were no humans at that time) to something completely non-humanoid in that short a time span, especially considering similar evolutionary pressures. I'd expect just about any near relative of H. erectus to have two arms, two legs, a head, and walk upright. But that level of "similar anatomy" wouldn't imply that H. sapiens as a species had evolved independently multiple times. $\endgroup$ Oct 19, 2021 at 21:15
  • $\begingroup$ @NuclearHoagie Erectus, Heidelbergensis, Neandertals, and Denisovans and Floresiensis were all human species roaming around 500k years ago, probably others undiscovered as well. $\endgroup$
    – Kilisi
    Oct 19, 2021 at 21:22
  • $\begingroup$ cannot put my finger on it, but I think it is a massive mistake to discount technology. IMO technology would probably be a driving factor in diversity. Dune touches on it with e.g. IX, Tleilax, guild navigators and that is perhaps an order of magnitude less time and also IMO fairly believable. $\endgroup$
    – Yorik
    Oct 20, 2021 at 18:57

5 Answers 5

13
$\begingroup$

Current science has proved through genetics that human species separated by up to a million years could and did interbreed.

So 500k years isn't an issue. They evolved slightly different morphology but Neandertals, Denisovans and perhaps even homo erectus and others were similar enough to interbreed with each other and our species. Denisovan mtDNA is thought to have diverged from that of modern humans and Neanderthals about 1,313,500–779,300 years ago. Yet there were multiple interbreeding events with both modern humans and Neandertals.

Papuans have traces of at least four interbreeding events with other sorts of humans. Neandertal and what we call Denisovan (because we have no idea what they were as there is no fossil record), but in fact three separate events occurred called Denisovan introgressions for very divergent so called Denisovans (but the three were at least as different to each other as they are to Neandertals)

According to this study it takes a million years for a species isolated from itself to become a new species. Other studies posit much longer periods of time. 500K just isn't long enough for enough divergence to take place in general terms. Only a major aberration in that time frame like the loss of a chromosome or other biological change could do it.

$\endgroup$
5
  • 2
    $\begingroup$ Technically the Neandertals & Co were our species just different race/subspecies as they could interbreed with us. $\endgroup$
    – Bartors
    Oct 20, 2021 at 7:47
  • 3
    $\begingroup$ @Bartors yeah, in the conventional sense, yet in anthropogeny they're different species. As are the Austrolapiths who in my opinion could also interbreed with each other. The definition of species is murky these days with hybrid Lion/Tigers etc,. I'm not even convinced humans couldn't interbreed with Australopithecus Afarensis if they were still around. Ligers aren't sterile either, they can breed with either and have offspring, yet the lion/tiger lines diverged 3 million years ago or more. No one says lions and tigers are the same species. The whole species idea needs rethinking. $\endgroup$
    – Kilisi
    Oct 20, 2021 at 8:02
  • $\begingroup$ Looks like there were only a couple of people who read the question before answering. $\endgroup$ Oct 20, 2021 at 13:47
  • $\begingroup$ /Only a major aberration in that time frame/ like a population bottleneck and founder effect from a tiny starting population $\endgroup$
    – Willk
    Oct 20, 2021 at 22:48
  • $\begingroup$ @Willk nope, we know the details of how those work out. Humans have been through several. $\endgroup$
    – Kilisi
    Oct 20, 2021 at 22:52
6
$\begingroup$

Genetic exchange.

Earth has no magic. But other places do! And those folks in the magic places tend towards the homely thru no fault of their own. So when they want smoking hot hotties you know where those other folks come looking: Earth. Magic users of the human persuasion looking to reproduce make periodic forays to the Earth and round up our prime genetic material in the form of assorted hotties, then bring all of them back for the good breeding.

Thus the human types on the farflung regions of humandom keep looking human because of the continuous readdition of human genes.

$\endgroup$
1
  • 3
    $\begingroup$ A slightly less tongue-in-cheek version of this might be: "echos of the magiclysm periodically transport people between planets involuntarily". It sucks for those people, but serves to keep all the various populations roughly similar. $\endgroup$
    – codeMonkey
    Oct 20, 2021 at 15:53
1
$\begingroup$

Humans contain a now damaged mutation inhibitor.

To survive the radiation common with magic, humans originally contained several DNA sequences which inhibit mutations and changes to DNA. This slowed reproduction, but meant that DNA was much more stable.

While this has long since mutated into uselessness in favour of faster reproduction, and so isn't obvious to earth humans, this in most worlds prevented most large scale changes. Only in the last hundred thousand years or so have humans been able to mutate, and this wasn't enough for any especially radical changes.

$\endgroup$
9
  • $\begingroup$ 500k isn't long enough anyway' $\endgroup$
    – Kilisi
    Oct 19, 2021 at 20:58
  • $\begingroup$ We already have humans with some fairly radical changes in the gene pool. Bottlenecks and genetic drift would be enough to amplify the changes on some planets. $\endgroup$
    – Nepene Nep
    Oct 19, 2021 at 20:59
  • $\begingroup$ Do you have any evidence of this? All humans can interbreed, if neandertals were still around we could breed with them. Nothing major has occurred in over a million years at the basic genetic level. $\endgroup$
    – Kilisi
    Oct 19, 2021 at 21:00
  • $\begingroup$ Check op's answer- they all need to be very similar anatomically. Suppose there's an extinction event, and only people with the mutation for six fingers survive. That wouldn't meet OP's requirements. $\endgroup$
    – Nepene Nep
    Oct 19, 2021 at 21:06
  • $\begingroup$ that would take an extreme problem to occur, not a generally likely outcome and could happen in any timeframe like the cell sugar change separating us from apes or the fused chromosome. Otherwise evolution doesn't happen that fast. But I'm waiting for your 'real' example because I never heard of any human population with 6 fingers. $\endgroup$
    – Kilisi
    Oct 19, 2021 at 21:10
1
$\begingroup$

It's all about the origin of life, the universe, and everything

Humans are everywhere because evolution was rigged from the start. And the two explanations below are not mutually exclusive.

A universal pattern

The universe is a great mystery. How it began, how it will end, or even will it end, there is no shortage of questions about it. Perhaps the universe was formed by an act of chaos, or perhaps an act of creation. Either way, it was formed with a pattern. Think of it as the code of a simulation, which creates emergent behaviour. There is some fluke or quirk, that funnels the program into patterns.

The universe has rules that we don't fully comprehend, and life as we know it is one of the patterns that emerges from it, and thus Earth-like ecosystems repeat throughout time and throughout space.

A common ancestor

Long ago, a sufficiently advanced race of predecessors seeded life across the universe. Accidentally or intentionally, they left the building blocks for life as they knew on a variety of suitable worlds. From there, having to face the similar environmental constraints, life evolved along similar paths.

Evolution isn't a completely chaotic process. Those that best fit their environment live long enough to perpetuate their genetic code, others go extinct. With the same starting point and the same conditions, it stands to reason that evolution would procude similar results.

$\endgroup$
2
  • $\begingroup$ The "common ancestor" is humans from Earth, 500k years prior to the time period of his story. The question is whether evolution will have them diverge too much over that period of time. $\endgroup$ Oct 20, 2021 at 15:39
  • $\begingroup$ @MichaelRichardson The humans were magically transported to a planet that already supports life. The common ancestor in this scenario would be a civilisation that seeded life there and on Earth in the first place. With both environments being roughly equal, the humans would already be fit for survival without much pressure to evolve. $\endgroup$ Oct 21, 2021 at 6:43
1
$\begingroup$

Nothing is unique on earth. The energy constraints, the plate tectonics, the environmental pressures. This physic of evolution, might make aliens at least mentally very similar to us.

Regarding human mimicry though, emulating the exact visuals, that would be wild. Why does that have to be natural though? Have several systems praolled by hostile nano-bots, who only allow there masters to exist? Humanity is gone, but due to its technology lingering on, all that is alive has to mimicry to be from earth at least on a visual level.

$\endgroup$
2
  • $\begingroup$ The question is about divergence over 500k years from a common, Human, ancestor. Not unrelated worlds having humans evolving independently. $\endgroup$ Oct 20, 2021 at 15:44
  • $\begingroup$ over 500k years the ancestry becomes irrelevant. On that timescale technology rewrites the dna or turns it into machinery. Our whole species is barely 300 k years old $\endgroup$
    – Pica
    Oct 20, 2021 at 17:37

You must log in to answer this question.

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