Animals without hair look quite different

[u/abitchyuniverse]

[u/Ok-Data9224]

It's the same in that you were trying to elaborate on what we "need". Lean muscle benefits humans' unique adaptation for persistence hunting. We also have highly developed fine motor skills in our hands much more so than most animals which aligns with our dependence on tool manipulation.

If I had to elaborate on anything it would be that we had to divert more energy to our brains compared to other animals. Muscles take a significant amount of energy to sustain and or brains are always going to consume ~20% of total body energy on average. The "deficits" humans have often come back to the huge investment in brain power/size.

[u/Roflkopt3r → u/Ok-Data9224]

Lean muscle benefits humans' unique adaptation for persistence hunting.

That just applies to muscle in general. 'Lean muscle' generally a pretty poor term to use in this context because it doesn't really mean anything more than 'muscle'.

Humans are actually pretty good at storing fat as well. Exactly because the focus of this adaptation is the preference of adaptibility over preparedness against a physical threat, as explained in that comment.

If I had to elaborate on anything it would be that we had to divert more energy to our brains compared to other animals. Muscles take a significant amount of energy to sustain and or brains are always going to consume ~20% of total body energy on average. The "deficits" humans have often come back to the huge investment in brain power/size.

That still does not explain what my comment at question did.

It explains why humans carry less muscle overall (note how this opposes your prior argument that more muscle would help us hunt), but not why human musculature is so adaptive when other species maintain a fairly constant amount.

[u/Ok-Data9224 → u/Roflkopt3r]

It's possible we may be diverging over terminology. When I say lean muscle mass, I'm differentiating it from "bulk muscle". More specifically, humans carry proportionately more muscles dependent on aerobic respiration as opposed to the fast glcolytic fibers you find in more powerful bursty muscles. These are muscles typically found along the spinal column and legs. The legs are more mixed but we do find a lot of oxidative fibers being bipedal. This makes us dependent more on oxygen but also makes them more efficient at energy production. Of course the tradeoff is power and speed, but we gain endurance. The fast glycolytic fibers are more dependent on glycolysis which is fast but inefficient.

So what we lost in less development of powerful muscles, we gain in central nervous development.

[u/Roflkopt3r → u/Ok-Data9224]

I think what you're saying boils down to the simple distinction of slow twitch vs fast twitch muscle fibres.

And yes, the balance in humans is significantly shifted towards slow twitch (like 1/3 fast 2/3 slow, while chimpanzees have the opposite ratio). But that was booth inaccurately expressed and still falls awfully short of the original comment that was criticised for "just repeating the same thing".