Why are humans so weak (pound for pound) compared to many other animals?
In: Biology
That’s a GREAT question! Humans seem really really stupid by comparison to animals like cheetahs or gorillas or… well basically every other animal, right? But at the same time, humans have been around for a really long time – something like 3 million years! – so we must be doing something right. But we don’t have armor, we don’t have speed, we don’t have claws…so what is it that makes us special?
Well there are a few theories out there, but my personal favorite is the “running man” theory. Humans have really, really big brains by comparison to other animals. And our brains are super complicated. It takes a LOT of food and energy to feed a brain like that. So we needed a way to get a lot of food – more food than most other animals get to eat. The “running man” theory basically says that humans evolved to run – not super fast like a cheetah – but to run super *far*.
By standing tall instead of crawling on all-fours like a cheetah, humans can get way more oxygen in their lungs. By having lean, long muscles instead of big bulky ones like a gorilla, we’re able to weigh a lot less, meaning we need to use less energy to run. And by shedding our fur and evolving the ability to sweat, we can cool our bodies down *while* we’re running. This one is *super* important because all other animals with fur on their bodies can’t cool down and run at the same time. At a certain point, their bodies get too hot and they have a choice – keep running and die or stop and cool down. But not humans! Humans can run for hundreds and hundreds of miles without stopping because we can sweat.
So to answer your question, the reason why humans are so weak compared to other animals is because we have big brains that need lots of food and the best way to get that food was to have bodies that could out-run all other animals.
Because we evolved large brains and use tools to control our environments and protect ourselves. We never needed to be that hench to get by.
For starters, we spend about 20% of our energy intake on running our big brains. On the plus side, our big brains do allow us to scurry up some really nutritious, high energy diets. So that’s not much a problem.
Muscles take a lot of energy to maintain. Diet permitting, our bodies increase or decrease our muscle mass depending on our level of exercise. Ie. it makes no sense to waste a lot of energy maintaining muscles if you spend all day behind a desk.
When we exercise and eat healthily, we’re pretty fit and strong really. We can stay active all day long. We’re fantastic runners. Some early humans were subsistence runners that would literally chase prey animals until they collapsed from exhaustion.
At the end of the day, every species works with the energy budget it’s got. Some animals survive by using as little energy as possible. Either living very slow lives like sloths or just being very lethargic until they briefly burst into action like a crocodile.
Some animals like cows eat very low nutrition food sources like grass but they spend almost every waking moment eating and every resting moment digesting, allowing them to grow big and muscular.
Some animals live very energetic lifestyles and as a result, need as much high nutrition food as they can find. Many kinds of mice, hummingbirds etc.
Humans are flexible. Our muscle mass can change quickly, we spend a lot of energy on our brains. But the payoff is that we can thrive pretty much anywhere without just growing dumb and big.
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