Maybe i am wrong, but everytime i see videos with cougars or gorillas they looks like Mr.Olimpia competitors
Their DNA and hormonal structures are different. Muscles require a lot of energy to maintain so an organism want to have enough muscle to move around, catch prey or defend themselves but not so much that they frequently run the risk of starving.
Humans don’t rely on speed or brute strength to catch and kill prey, we are better off staying lean and dexterous. It is way more important for us to have weaker muscles with very fine motor skills so that we can manipulate tools compared to run sprinting or striking power.
Aside from exercise and hormones, muscle growth is heavily regulated by a protein called myostatin. It tells the muscle fibers to slow down their growth, so having less myostatin means your muscles will grow more without exercise.
Even if they don’t work out, boys will pack on plenty of extra muscle as they grow into men simply because their hormones and genes tell them to, and animals are no different, except that their genes tell them to grow way more muscle.
Muscles grow in response to exercise, but it’s not like exercise actually powers muscle growth in any way. It’s just your body deciding to grow more muscle. But the “decision” of how much muscle to grown is a combination of environment, behavior and genetics. Some species naturally have more muscular physiques, meaning their bodies grow larger muscles by default, even without exercise. It’s simply encoded in their DNA that they are more muscular.
Muscular animals have to be muscular to survive in their ecological niche. Gorillas have to climb trees and possibly fight each other. Cougars have to run fast and kill their prey. We humans, in contrast, rely more on our intelligence and ability to craft and use tools, so we don’t need to be very muscular by default.
That’s not to say we have no physical prowess, though. We *are* built rather well for endurance running, and thus for persistence hunting. We have a great ability to cool ourselves down by sweating, whereas many other animals overheat if they run for a long time. We have achilles tendons that act like springs that store and release energy, which allow us to run faster and more efficiently. We have a nuchal ligament in our neck that stabilizes our head while running. And we (obviously) run on two legs, which is slower but more efficient than four-legged running.
they are quite active, they do not eat sugary or processed foods, then walk everywhere and do not drive.
All these small factors contribute for it.
If you only eat healthy food, and do activity all day, you also get quite “muscular”.