eli5: How come gorillas are so muscular without working out and on a diet of mostly leaves and fruits?
In: Biology
Genetics.
Their genes determin everything from gender to height.
Most of these genes have been selected through a process known as natural selection.
One really good gene for the survival of a gorilla is one for muscle growth. Also, gorillas are a lot heavier than us and they move around on their arms and legs. This amounts to a pretty good work out.
Put a human on anabolic steroids, feed them 2500kcal of broccoli per day (that’s 200g of protein) and they would be able to gain a lot of muscle.
With adequate protein supply our muscle mass is limited by hormone levels and sensitivity to hormones. Humans evolved the levels we have because apparently it was just the right amount of muscle to have. For gorillas it seems to be advantageous to have more muscle mass.
Things like bamboo shoots contain surprisingly much protein per calorie.
Gorillas are smart but they still mostly have to survive on their strength. As a result, a gorilla’s biology converts its diet into lots of muscle, even though the gorilla only eats shoots and leaves.
A human on the other hand does not need to survive so much on its strength. As humans our biology has evolved to convert our diet into brain development, so that we can imagine, develop, and master the use of tools and weapons. Thus, unlike a gorilla, a human eats, shoots, and leaves.
By the way, to get enough nutrition to maintain that body mass, it’s estimated that an adult male gorilla eats up to [65-75 lbs (30-32kgs) of plant matter per day.](https://www.wildgorillasafaris.com/about-gorillas/what-do-gorilla-eat.html)
How did they get enough calories to build those muscles? By spending half of their waking hours eating leaves and fruit, far more than a human spends eating.
How did those calories all get directed to muscle growth? Genetics.
The question ~~actually~~ should be, ‘Why don’t humans look all buff like many mamnals, to which the answer is that we developed the ability to adapt to our physique by growing muscle through constant exertion, and losing it during periods lacking constant exertion. This enables us to be more efficient, better survive periods of famine, and eventually led to developing a lot of skills because we don’t have to spend all day eating.
I’m surprised nobody is talking about myostatin in humans and the lack of it in many animals.
Edit: Search for Wendy the Whippet or Bully Whippet Syndrome for extreme examples of myostatin mutations in animals that normally have myostatin (the Mutation limits or stops it).
Edit2: [Myostatin](https://en.m.wikipedia.org/wiki/Myostatin)
>Myostatin (also known as growth differentiation factor 8, abbreviated GDF8) is a myokine, a protein produced and released by myocytes that acts on muscle cells to inhibit muscle cell growth…
>Animals lacking myostatin or animals treated with substances such as follistatin that block the binding of myostatin to its receptor have significantly larger muscles. Thus, reduction of myostatin could potentially benefit the livestock industry, with even a 20 percent reduction in myostatin levels potentially having a large effect on the development of muscles.[21]
Edit 3:
[Wendy the Whippet](https://www.google.com/search?q=Wendy+the+Whippet&oq=Wendy+the&aqs=chrome.0.69i59j69i57j69i60l2.1895j0j4&client=ms-android-motorola-rev2&sourceid=chrome-mobile&ie=UTF-8)
I’m surprised looking through the comments that the actual reason isn’t being talked about.
Myostatin is a protein produced by humans that inhibits muscle growth. It’s thought to be an evolutionary advantage in times of food scarcity because by limiting muscle growth it reduces the calories needed for the body to maintain itself.
Gorillas lack that protein so they have a much easier time building and maintaining muscle despite their diet.
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