So, I'm working on my own setting. It is close to the classic fantasy, so it has a similar set of races. But this setting is mostly science fiction, so the races present in it must have a logical and scientific explanation. Today I'm looking for an explanation for the evolution of the orcs. Usually, considering certain creatures, they are created in the image of their habitat. I want to try to do the opposite and create a place of habitation with you, starting from the creatures that inhabit this place.

Orcs in this setting should initially be large (not less than two meters and not lighter than a hundred kilograms), green, have a prominent lower jaw, protruding fangs and impressive musculature. Their society should be tribal. The tribes, as well as their entire society, are ruled by the cult of power. That is, the strongest orc becomes the leader and it is to him that the best females and males are given. At the same time, equality between the sexes should prevail in their societies. That is, if the female orc turns out to be stronger than the male orc, she will become the leader and she will receive the best males. Their technological level itself is similar to our Stone Age, but sometimes advanced technologies from other planets seep into their society.

I hope that these introductory data will be enough to create a planet on which such a race could develop. Also I accept amendments in some aspects. I understand that green skin color is not possible for living creatures, so you can give these orcs a different skin color. I hope that it will turn out to be a race that is considered on a galactic scale backward and possibly barbaric. These orcs can be slaves or gladiators, and rarely do they reach any significant heights on a galactic scale.

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    $\begingroup$ I believe if you review the tag descriptions you will find that science-based and science-fiction are mutually exclusive, and are not to be used in tandem. $\endgroup$ Commented Jun 12 at 20:27
  • $\begingroup$ I deleted science-fiction tag. Thanks for your comment $\endgroup$ Commented Jun 12 at 20:41
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    $\begingroup$ This is very close to worldbuilding.stackexchange.com/questions/167531/… - please have a look at the answers and see if they answer your question $\endgroup$ Commented Jun 12 at 22:59
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    $\begingroup$ I'm with @KerrAvon2055 and TheDemonLord. Asking about the nature of the planet is almost irrelevant. If you're doomed to want to scientifically explain your fantasy (*sigh*) then you're stuck with the reality that the one and only life-bearing world we know about is Earth. That means rationalizing your orcs in terms of terrestrial critters (like frogs for green skin) and that means this quesiton is a duplicate of the link Kerr provided. $\endgroup$
    – JBH
    Commented Jun 13 at 0:39
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    $\begingroup$ @o.m. Not if you're sticking with science-based. E.G., all creatures on a higher gravity planet would be stronger compared to a lower gravity planet. In other words, the Orcs' strength compared to other creatures can't be rationalized by gravity unless they've been transported to a lower gravity planet, which isn't mentioned by the OP. And social patterns have nothing at all to do with planetary characteristics. $\endgroup$
    – JBH
    Commented Jun 13 at 5:42

3 Answers 3


There is a lot to consider here.

You want your orcs to be large, green strong, fierce, egalitarian and have fangs.

Size: there is nothing inherently wrong with humanoids of that size. The main problem is diet: supporting a 100kg, 2 meter tall humanoid takes a lot of nutrients. There is a reason why early humans were around 1,5 meter tall and wiry - its more efficient. Gorillas, as consumate herbovires can easily reach that size, but the same herbivore lifestyle makes them unlikely to advance technologically (no gain in it), gain fangs, or even become egalitarian (big herbivores tend to be haremic and sexually dimorphic).

Solution: make the orcs semi-aquatic! Imagine orcs as a sort of humanoid answer to seals, walruses and otters.

This solves most of your problems. A semi-aquatic mammal, especially omnivorous one, could easily grow to be 2meter tall, and over 100kg. There is plenty of food in the coastal environement. Fangs would be useful for the same reason walrus tusks are: to chisel away edible animals from the surface of the underwater rocks. An aquatic animal would need no fur, and would quickly lose it. It might gain gray-green coloration to fit with its environment better (same reason dolphins are dull gray). Diet of algae and seaweed might also add to their coloration, and so is consuming copper-blooded crustaceans in large amounts. A wading, semi-aquatic animal that can switch environments would not work well in big herds or in harem-like structures, because both males and females would be able to wander off easily. This would in turn promote mostly uniform size and strength between genders, small packs, and egalitarian power structure based on ability and strength rather than sex.

So, the planet:

I would stick with Earth size and gravity, as well as atmosphere. No need to tinker here. But I would greatly change the geography. Break up and spread the continents, so that the vast majority of landmasses is broken into archipelagos, and any true continents are complex affairs of peninsulas, not uniform shapes. You would want to maximize the coastal area, and break oceans apart into countless small, often shallow seas. The continents themselves should also have plenty of lakes, rivers, and swamps. Basically, you want a planet perfectly suited for semi-aquatic creatures like seals, penguins, otters, frogs etc, with one sapient race: the Orcs.

This would also keep your Orcs in the Stone Age much easier. Orcish populations would have easy time spreading all over the planet, when every landmass is in swimming distance. They would need no advancement like agriculture if they can easily feed themselves off the sea. They would quickly invent watercraft, but would be limited by the lower availability of wood in their world. They would be great at fishing and invent countless technologies towards that end, but all of them primitive. A Costal Planet would be one where metal ore is harder to get. Bog iron might be occasionally available, but the constant churn of the seas and the islands would cause most of the other metal ores to eventually wash to the bottom of the sea. Clay for pottery etc, would exist, but again, mostly underwater. There would be very little coal (as over millions of years forests would sink below the ocean, not underground) but plenty of oil...which would be deep underwater as well.

A Coastal Planet would by necessity, have a lot of small but active volcanoes, so there would be plenty of volcanic obsidian around. Similarly, the churn of the shallow seas would produce significantly more chalky rock with flint and chert bulbs in it. Essentially, material for stone tools would be far easier to get.

What about climate? This is near impossible to answer, because how complex climate patterns can become, especially around coasts. But I would guess a climate that is warmer, but overall more humid than our Earth, due to the coastal structure forcibly making it milder.

So, imagine a planet that is the same size as Earth, same gravity, and chemical make-up. Near identical atmosphere and similar biosphere. The entire planet is littered with archipelagos and blotch-shaped small continents, separated by shallow seas. Everything between the tropics looks like Caribbean essentially. Everything between the tropics and the sub-polar region looks like Mediterrean, then as you go further North looks more and more like Scandinavia and the British Isles. The Sub-polar regions look a bit like the Great Lakes area and Northern Canada, while the actual polar regions look like chopped up Iceland with a lot of half-frozen peninsulas and labyrinthine bays.

its a world where you can take a canoe trip from the Equator almost all the way to the Poles and never be out of sight of land, and with almost every island be inhabitable (and quite often inhabited by some unique tiny tribe of Orcs, fiercely protective of their spot).

One thing you can play with, is the size and distance of their Moon. No moon, or a far smaller/ further distanced one, would make the seas sluggish with almost no tides. Bigger of closer Moon would make tides much more dramatic, and thus force the Orcs to move more and be more nomadic, as some islands would be just too awkward to live on with the tides flooding them constantly.

On such a planet, the Orcs would evolve into something similar to a Polynesian/Maori culture, with a hint of metal-less, Stone Age Vikings.

  • $\begingroup$ Given their tusks and disposition, orcs could have evolved from an aquatic, walrus-like creature. $\endgroup$ Commented Jun 13 at 10:55
  • $\begingroup$ @IndigoGriffin Exactly. Either that, or they started as standard humanoid apes and then underwent "walrusification", turning into semi-aquatic apes. I think the second is more likely, we know of plenty of mammal lineages that became semi-aquatic or aquatic, but none that did the reverse. $\endgroup$ Commented Jun 13 at 12:15
  • $\begingroup$ The tides will also depend on the influence of the star, not just the moon(s). (On Earth, the tug of the sun is about half that of the moon.) $\endgroup$ Commented Jun 13 at 23:25
  • $\begingroup$ Gorillas don't need to gain fangs, they already have them... $\endgroup$ Commented Jun 14 at 16:30

Your requirements come down to three things: Size and strength, cosmetics like coloring, and behavior/sociology.

  • Your desired size and strength are not dramatically out of touch with human numbers. Could be chance, or you combine factors like
    • slightly higher gravity, to require more muscles,
    • slightly colder climate, to encourage a better ratio of mass to skin (that is, a larger size).
  • Your desired coloring might be something in the alien biosphere. There are animals with greenish color. The fangs could have been due to a choice of diet and prey of the ancestor species, consider the real-world baboon.
    You will have to make the fundamental decision if the alien ecology works on Earth-compatible sugars, amino acids, etc., or not. Can Orcs survive on Earth food, possibly with some vitamin supplements, or would that be instantly poisoning?
  • Your desired social patterns might be encouraged if your female Orcs are less restricted by childbirth and childcare. Make them not mammalian, and both/all parents can care for the offspring. Perhaps even egg-laying, to reduce the burden on the female and to allow the male do do some of the incubating.
    As the proto-Orcs got sentient, the pattern of the alphas getting more reproductive rights would be somewhat dampened but not replaced. A sentient Orc might not abandon a partner just because someone else won the arm-wrestling match, but strong ones would be seen as sexy.
  • $\begingroup$ This leads me to think that in order to preserve equality between the sexes and to preserve the green color of their skin, these orcs could become evolved reptiles. $\endgroup$ Commented Jun 13 at 7:51
  • $\begingroup$ @AlexanderHerman, reptile men are a different Fantasy archetype. And an Earth reptile would be more closely related to an (Earth) jellyfish than to those Orcs. $\endgroup$
    – o.m.
    Commented Jun 13 at 10:20

The first step in having a science-based orc species is alien seeding. The liklihood of an alien biome spontaneously evolving a humanoid species is probably so small as to be negligible.

However, if we assume that these orcs live on a world that was seeded with life from Earth's prehistory, then we have a far better chance of being able to direct the evolution of orcs. Of course, that would mean that there would probably be at least two kingdoms of animals, those of terrestrial origin, and those of native origin, however I can't speak to how common members of each kingdom would be.

We could also handwave evolution on an alien planet to the point of the evolution of primates to be identical to that of Earth. That's the OP's choice.

Ideally, we would have our precursor primates introduced to their new environment around 55 million years ago. This should give plenty of time for them to adapt to their new environment.

At the time when these primates were seeded onto their new world, that world shouldn't be too different from the world from which they came, around the same temperature, pressure, atmospheric oxygen content, with sufficiently similar vegetation that they won't starve... perhaps from previous transplantation events.

The immediate environmental differences would need to have higher gravity, perhaps 1.15g to 1.25g, in order to encourage higher muscle mass without immediately making the environment inhospitable to the seeded primates. It should also have a star that emits less UV radiation, perhaps a K2-K5 main sequence (V) orange star. The lower UV levels will encourage lower amounts of fur and melanin, while not completely obviating the need for UV protection.

The next thing needed would be unique to this new planet. Beginning soon (on an evolutionary timescale, <1MYr) after the introduction of the terrestrial primates (and other species), we would need to have some native predators begin to adapt to eating these primates. They would need to be not so lethal as to quickly wipe out the primates, but sufficient to place pressure upon them. They would also need to hunt by sight, and to have trouble discriminating between shades of green, yet still being capable of discriminating between green and other colours. This would encourage the evolution of green colouration. 'Green' need not mean a green pigment, since blue and yellow pigments can combine to produce an apparently green colouration.

Alongside the evolution of the primate's predators, we would also need gradual global warming that would encourage less insulating fur and encourage the primates skin rather than their fur to become green. We could have many warm seas that would encourage the primates to swim, a situation thought to have contributed to humans' relative hairlessness.

At the point where primates have evolved to be relatively hairless and green, we can introduce selection pressures to encourage intelligence in the orcs' precursors, and to encourage a plains-dwelling lifestyle. Climate change at the same time could contribute to the contraction of forests, and long grasses would encourage an upright posture. The selection pressures that encourage intelligence are sociability and social heirarchy.

As part of the social heirarchy, the orcs' precursor could evolve to have wrestling as a part of the sexual selection pressures. Other sexual selection pressures would be bare, relatively furless skin, and a protruding lower jaw with tusks.

At this time, we could have more climate change, this time leading toward a cooler climate. With the pre-orcs selecting for muscular, relatively furless, green bodies with heavy jaws and tusks, sexual selection combined with climatic selection would favour bigger pre-orcs rather than furrier pre-orcs. Bigger means a lower surface area to volume ratio, enabling better conservation of heat. It also means more muscle for wrestling, and more height for overbearing opponents. With the higher gravity, this would favour big, muscular, upright primates.

Climate change, if sufficiently rapid, could cause a change in environment sufficiently fast to select for pre-orcs with sufficient intelligence to adapt, and intelligence is itself a self-selecting trait.

It is concievable that these orcs could have evolved an egalitarian society, where gender is irrelevant to social dominance. The ability to wrestle well and survive in a dangerous world would be sufficient to establish a social heirarchy. With large tribes and a social class of nursemaids, mothers who nurse other females' infants while their more dominant mothers go out to hunt or forage, socially dominant females become possible. We could have a situation where socially dominant members of both genders develop characteristics that display their dominance, such as heavy jaws and larger tusks, in much the same way as dominant male orangutans develop prominent cheek pads.

With sufficient intelligence and rapid climate change driving the evolution of intelligence, tool use would become likely. In an environment where food is becoming scarce, mere wrestling for social dominance would not be sufficient, and population pressures may lead to outright war, where orc kills orc in order to take or keep their territory and reduce the pressure upon food resources. Once you have intelligence, further global cooling can lead to the invention of clothing rather than increasing furriness.

At this point, you have orcs. Big, strong, green, lantern-jawed and tusked orcs. It's then just a matter of how advanced their technology has become, since there's no reason why they may not eventually progress to the space age.

  • $\begingroup$ I take it you mean the artificial appearance of orcs on this planet? $\endgroup$ Commented Jun 13 at 8:58
  • $\begingroup$ @AlexanderHerman I mean that early primates could have been transported to this planet, or at least the evolution of this new world's 'primates' to that point has somehow been identical to the evolution of primates on Earth. $\endgroup$
    – Monty Wild
    Commented Jun 13 at 9:00

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