I'm thinking about using this as a sort of meta explanation for how Orcs (and possibly other things as well) are different than humans (in muscularity), but I'm not entirely sure what the result of this would be.

What would be the expected appearance of a humanoid race with a suppressed myostatin gene? (Includes Men, Women, and Children)

  • (Bonus points for -accurate- picture examples, but explanations and approximations are perfectly valid as well.)

The Belgian Blue Cow is a notable example of such a mutation, and a helpful starting point for determining answers.


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    $\begingroup$ I asked a similar question a while back, with pretty much the same idea in mind. You might find it useful: worldbuilding.stackexchange.com/questions/10232/… $\endgroup$
    – user7076
    Commented May 1, 2017 at 15:41
  • $\begingroup$ This is a really cool idea as a way to create Orcs, etc. +1 $\endgroup$
    – Paul TIKI
    Commented May 1, 2017 at 16:48
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    $\begingroup$ I add some info as comment because it does not answer the question. There is a very good reason for limiting muscle growth (myostatin) and the linked articles seems to be oversensational ("Wow, muscles"). Too many muscles increase both your basal metabolic rate and your necessary protein intake: In a famine such people die first. Tendons and bones can adjust themselves to higher load, but are prone to overstrain and cause permanent damage.Muscles need oxgen to work, so the whole cardiovascular system is under extreme stress. So for the story you could point out these weaknesses. $\endgroup$ Commented May 2, 2017 at 0:21

3 Answers 3


A deficiency in myostatin can and does occur in humans. Take, for example, a German boy who could lift 7-lb. weights with arms extended when he was 5 years old. You can find an image of him when he was a few months old in the article. Since his identity was not revealed, current images are likely hard to find. (Also, I don't want to be put on another watch list for trying to find them...)

Researchers have expressed health concerns in the boy's future due to his increased muscle mass. (Warning: paywall ahead) Research shows that a reduction in myostatin may also cause an increase in bone formation. Additionally, animal breeds with a myostatin deficiency have reproduction, dietary, and care issues relating to their increased muscle mass.

Humanoids with a myostatin deficiency would be bulkier through increased muscle and bone mass, but I would also anticipate them being fewer in number, due to all the special concerns that apply.

It's important to note that most breeds with a myostatin deficiency mutation have been engineered or selectively bred specifically for that trait, such as the Belgian Blue. This may be because nature cannot normally support such a creature due to the health concerns, especially as they apply towards reproduction.


From http://journals.plos.org/plosgenetics/articleid=10.1371/journal.pgen.0030079

enter image description here

This one is nice because you can see the difference between the +/+ wild type, the mh/+ heterozygote and the double mutant.

But my favorite picture of the myostatin mutant whippets is this one. enter image description here

because they both look like good dogs.

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    $\begingroup$ They're good dogs, Bront. $\endgroup$
    – Mayube
    Commented May 2, 2017 at 8:20

I am the first female to score a rushing touchdown in a male high-school varsity football game. I was 4'11" 130 lbs and even a starter my junior year as a fullback and outside linebacker. I thought the girls from softball were being too girly when they couldn't bench their weight or leg press around 300lb like me. I didn't realize it was me that was extremely different and they were not just being girly. This became an issue because myostatin affects muscles and the heart is a muscle. My heart disease is hypertrophic cardiomyopathy. I would max PT tests in Jrotc and lacked flexibility in the sit reach test. I lacked flexibility. My calves are still huge and I have active duty spinal cord injury and I haven't worked out in 10+ years. The problem with lacking the ability to get around the calf muscles just tighten. So they are making my toes point. I must stretch and massage them every day. I have to put a toe on a step and slightly lower the ball of my foot down to stretch the tendon. I am not sure if it's an rh negative birth defect. I have all of those symptoms too, extra rib, vertebrae, no wisdom teeth kind of stuff. My mother is rh negative and she is the same but her muscles were not as extreme as mine. But she never did actual body building with a football team like me. But it's painful and possibly a short life, coincidently that is often the results of early genetic altering. I thought rh neg alien link is an interesting topic. If so I'm a damn alien lol

  • $\begingroup$ Thanks so much for this answer! I don't mean to make light of your condition, but your firsthand experience offers a much deeper understanding here. I appreciate you sharing it! $\endgroup$ Commented May 23, 2022 at 23:34

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