This is loosely linked to my nature Mage questions. In my fantasy world I want a race of Orcs. These are the characteristics they have to have:

  • Stand between 6 and 7 feet tall

  • Have crude weapons

  • Reproduce quickly

  • Reach Sexual maturity at age five and mental maturity at age 15

  • Live a maximum of 25 years

  • Have mindset of 15 year old human children

  • unable to wield magic

How fast would the cells of these orcs have to grow and divide to reach these growth rates and reduce mental capacity to that of a fifteen year old human child? How realistic would this be to a reader?

Note that while there is magic in my world, I want a little handwavium used here as possible. Please try to include known biological processes and cell growth rates as a basis for your answer.

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    $\begingroup$ Well humans with a pituitary gland problem can reach 6 feet in 5 years. $\endgroup$
    – bowlturner
    Apr 17, 2015 at 16:15
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    $\begingroup$ Sounds like these orcs would be highly energy-dependent (so likely carnivores) go through an extreme level of competitiveness in their early growth, be highly carnal in their adult lives, and have very few elders hanging about dispensing much wisdom...certainly sounds like orcs to me. $\endgroup$
    – Zibbobz
    Apr 17, 2015 at 16:23
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    $\begingroup$ I'm not seeing any relevance to the linked questions. The only commonality I see is that you asked them. Is it just self-promotion? $\endgroup$
    – Samuel
    Apr 17, 2015 at 17:18
  • $\begingroup$ @Samuel I mention the Orc wars in one of my other [linked] questions in the comments and thought that I would add another plot twist to the story: Orcs aren't really extinct. The Orc wars were fought by humanity against the orcs because the orcs were out competing both humans and elves for resources. In my story it will be uncovered that they survived for centuries in abandoned mountain fortresses.....the same ones that human refugees want to flee to. I am going to ask another question on how to get them to agree to be peaceful. I first needed to decide their characteristics. $\endgroup$
    – Jax
    Apr 17, 2015 at 17:48
  • $\begingroup$ @DJMethaneMan In the comments of one of the five linked questions mentions some backstory about orcs... Ah, here it is, "the extinction of the orcs many many millennia previous in the Dragon Wars". Is that right? Did it change to Orc Wars and centuries instead of Dragons and millennia, or am I not finding the right one? I can't say that clears up why the questions are linked. $\endgroup$
    – Samuel
    Apr 17, 2015 at 17:57

2 Answers 2


These are all just fine.

Stand between 6 and 7 feet tall

Just feed them well, this is not far off from human average height. Nothing magical required.

Have crude weapons

Ok, well they're basically 15 year old human children. Crude weapons is all they can make.

Reproduce quickly & reach sexual maturity at age five

Reproducing quickly will be a result of sexual maturity at five years old. Reaching sexual maturity that soon for a humanoid is not unfathomable, but being physically developed enough to actually bear children is the main problem. Hormonal changes could conceivably allow a human to achieve this, so it's not too unlikely for an orc.

[Reach] mental maturity at age 15

This is rather quick compared to most humans, but considering this is old enough to be a great-grandfather and the general hard-knock life of an orc, it's not unlikely.

Live a maximum of 25 years

If you had a great-great-great grandfather still kicking around you'd probably think it was about time he went off to meet Gruumsh. Orcs aren't a civilized society, this maximum age would be easily believable.

Have mindset of 15 year old human children

Again, see many humans alive today. Additionally as this would be older than the average age for the orcs, it's easily believed.

unable to wield magic

I can't wield magic, I wouldn't be surprised to learn another creature can't either.


almost all of this is trivial to say "they just evolved that way". Species of all kinds of intellectual levels have evolved, with different lifespans and sexual maturity. For the most part you can get away with saying "they are just that way". The only real world building issue I could fight over is the intellect levels vs tools.

15 year olds are sometimes rather emotionally immature, but they aren't idiots. a 15 year old can make far better then 'crude tools' himself, I've seen some really skilled 15 year olds. Once taught how to do something they can do it pretty well, and it only takes one smart 15 year old to figure out how to do something. Plus, if they live around smarter humans they just have to be taught by smarter people how to make better tools and then remember. In short, a race of 15 year olds should have more then 'crude tools'.

Bonobos have crude tools, bonobos raised by humans can cook meals over fire or on a stove, work light switches and even touchpads, and generally interact with the tools we provide them pretty well. If you make a species much smarter then bonobos your have to put more thought into how their intellect vs their tools interact to avoid the, all to common in fantasy, mistake of making 'primative' tribes that are too smart to continue living so primitively.

In particular if your orcs are near humans or other intelligent races they will be getting tech and ideas from those. Even if they are not smart enough to create they can be smart enough to USE it.

You could have them be smart and their lack of tools is simply due to lack of resources to build or make them, the same way that third world countries still rely on 'primitive' hunting techniques for food because, even though anyone can tell them how to build advanced guns, they still don't have resources to make, craft, and maintain a large number of them. This would be the easiest approach to explain the tool vs intellect dependency. However, then you need to explain why they have limited resources, and why they don't just trade with, or raid, nearby humans for their goods.

Alternatively you can make them actually less intelligent, with actual cognitive limitations preventing understanding the use of advanced tools. However, if you do that your want to put some real thought into how to make culture and technology equivalent to their actual intellect. In particular avoid trying to say "their just like us humans, but stupid". They won't be able to have the same sort of conversations and philosophies as humans if they are less intelligent, this would also effect culture and beliefs and many things. Their cognitive difference will result in a very different species then humans. This is worth it's own separate world building question actually, development of culture and technology for a cognitively limited sapient species.

IF you want to go with hard science approach I could nitpick on some other minor details, though I think they are all small enough that you could be forgiven for taking poetic license on them. The rest is major nitpick and your welcome to skip it!!!!

First, sexual and mental maturity are awfully far away. Sexual and mental maturity should be closer together. Humans are much closer when it comes to our mental and sexual maturity. We may consider 20 to be be 'adult' now of days, but we have developed most of our mental abilities long before that, we have room to learn more, were always learning, but our cognitive abilities are mostly complete at a much closer age. Besides, if we reach sexual maturity around 10 then we would have to reach mental maturity at 30 to keep with your ratio.

Related to issue of sexual maturity: For orcs to evolve intellect they would need to be heavily K selected species. K select species don't tend to reach maturity at such a young age anyways. Look at most other primates. Bonobo reach sexual maturity at age 9, and their err...sexual lifestyle would encourage quick sexual maturity. Chimps reach sexual maturity after humans. It's the same for nearly all 'intelligent' animals, they have long childhoods, and these creatures are all less intelligent, and smaller, then your orcs.

There are many reasons for this, the short version is that intelligence means less instincts, you need to learn how to use your intellect to survive. You won't survive on your own until you have learned, and so you need parental investment much longer which generally means delayed sexual maturity. This is only one part of it, all K select species have delayed sexual maturity and sapient practically necessitates K select strategy.

Your orcs are also much larger then the other intelligent animals. The larger a species is the longer it takes to reach sexual maturity in general.

In short for sexual maturity to be realistic I would push it back to closer to us, 8-10 lets say. I would also say that the males at least must wait much longer before able to compete sexually for females. Rather or not the females begin to reproduce as soon as they reach maturity depends on your society, but most likely they would if your assuming a less intelligent species then humans. Lower intellect means their less likely to have complex cultures which would discourage female from reproducing 'too soon'.

If you really want reproduction at a young age It could be done, but only with selective pressures. Maybe carrying a child to term is difficult enough that they start reproducing early to have more years of trying to conceive, with parents helping to care for grandchildren when their children are not yet ready to care for the child. However, your need either very high infant mortality (but very low death in childbirth), or simple difficulty with conception or carrying to term to make this work; along with grandparent investment being more common then most animals. Of course grandparent investment would in turn place evolutionary pressures to encourage more intellect to evolve in the orcs technically; but maybe they are evolving to greater intellect and just haven't gotten to our level yet.

However, these are both nitpicks from someone who really likes considering evolution. I'm pretty sure you could ignore most of this and have few, if any, complain. I would not scream in outrage if you had your orcs as you described with little further justification. So long as you don't also make them always chaotic evil that is :)

  • $\begingroup$ Being a person who is over thirty, I would argue that mental maturity is not reached when humans are twenty, certainly not before that. Twenty-year-old me would have disagreed, but so would twelve-year-old me. This is one of those "you'll understand when you're older" issues. Though so people certainly stop developing when they're twenty, that's unfortunately not the same thing as reaching maturity. $\endgroup$
    – Samuel
    Apr 17, 2015 at 17:13
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    $\begingroup$ @Samuel I said mental maturity, not emotional. When it comes to actual brain development it's all finished when puberty is exited, and much of the later brain development is more about emotional maturity then intellectual anyways. I'm taking his phrase "mental maturity" literally, though you could argue too literally depending on his original meaning by the statement :) The reason I make this distinction is because most of the later 'maturing' is due to our intellect and ability to learn, if you limit their intellect you limit the ability to 'mature' after physical brain development is done $\endgroup$
    – dsollen
    Apr 17, 2015 at 17:24
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    $\begingroup$ Mental maturity is distinct from physical maturity, but I'm not seeing the distinction you're trying to make. Emotions are a mental state, both intellect and emotion are all part of mental maturity. If you're talking about brain structures that's physical maturity, the software, if you will, be it emotional or intellectual, is mental maturity. $\endgroup$
    – Samuel
    Apr 17, 2015 at 17:33
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    $\begingroup$ Many of the emotional development in later life comes from long-term learning, we make mistakes and learn from them and better ourselves. The less cognitive advanced a species is the less it will relay on this long term growth because they don't have the same ability to learn and grow. It's rare for humans to have such potential to grow as people! This is why less cognitive species are harder to write, they don't learn and grow the same way we do. If they could grow as people later in life as well as us then they can think as well as us and should be as advanced as us. $\endgroup$
    – dsollen
    Apr 17, 2015 at 17:43

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