Eli5: How do apes like chimps and gorillas have extraordinary strength, and are well muscled all year round – while humans need to constantly train their whole life to have even a fraction of that strength?

Question

It’s not like these apes do any strenuous activity besides the occasional branch swinging (or breaking).

Whereas a bodybuilder regularly lifting 80+ kgs year round is still outmatched by these apes living a relatively relaxed lifestyle.

In: 8644

Answer 1

Our muscles that move our limbs are generally made up of two kinds of muscle fibres.

“Fast-twitch” muscle fibres are extremely strong and quick.

“Slow-twitch” muscle fibres are weak, but are energy-efficient and last long for things that require endurance.

In humans, a majority of muscle fibres are slow-twitch.
In other apes, a majority are fast-twitch (e.g., chimps have a 2:1 fast:slow ratio).

In addition, humans have more “small motor units” controlling their muscles.
We’re good at things that require a lot of precision.

Other apes do not have very neat handwriting, are pretty shit at knitting, and couldn’t throw a slider to save their lives.
When they move their muscles, they don’t have very fine control, and tend to move their limbs in exaggerated (overly-strong) ways.
A side-effect of that is that they tend to work their muscles harder than humans when doing small things, and effectively end up doing a bit more exercise.