We sometimes hear stories about chimpanzees attacking humans, where the latter come out with some horrific injuries, and we also see pictures of chimps generally looking as hench as all hell.
So why are chimps so much stronger than humans? How is it they’re able to rip lumps out of people with their bare hands? There’s a pretty simple answer – it’s down to their nervous systems.
Humans have evolved to have better fine motor skills, to work with intricate details, thanks to more neurons and grey matter in the brain. Chimps on the other hand, relative to body mass, have much less grey matter in their spinal cords than humans have. Grey matter contains a large concentration of motor neurons, which means that having less grey matter results in less control over the muscles. Instead, chimps enjoy a much more explosive nervous system as a result. Imagine a bull in a china shop. Not much control but lots of force.
It’s true that chimps and gorillas have much bigger upper body muscles than humans anyway, but the nervous system factor counts for a lot.
We humans have also evolved to use our muscles more gradually over time, making us more natural long-distance runners, whereas the great apes are more natural sprinters and jumpers, better able to use their muscles to explode and apply large forces quickly. So with chimpanzees you have an organism that has a much better developed upper body musculature than humans, that can be utilised with greater nervous excitability.
It just goes to show how important the nervous system is when it comes to strength. Bigger muscles and/or more muscle fibers are central, but you also need an excitable nervous system (more power and explosiveness), and less ‘viscosity’ in your nervous system (high frequency and lots of practice at a specific movement, ‘greasing the groove’ as Pavel Tsatsouline would put it).