Seems like a fairly inefficient system tbqh – is it because we’re eating the wrong stuff? or is it because living organisms create a fixed amount of waste no matter what? Poop is weird. I’d like to understand it better.
In: Biology
Poop is made of many things, mostly water. Like nearly every process in the human body, it needs water to keep things moving along properly. A good portion of the dry weight of poop is actually bacteria. Your intestines are full of trillions of bacteria, and a bunch of them get bound up in the stuff that moves through them. The rest of it is mostly fiber, which our bodies lack the enzymes to break down. Poop also contains cellular debris from your body’s normal processes of maintenance and upkeep.
I’m not clear on the inefficiency premise of the question
How efficient is the human digestive system?
byu/Its_raining_bacon inaskscience
I’d like to defend poop by noting that it’s a very good fertilizer. What we call “waste” is actually a helpful component in producing even more food. So if the system looks “inefficient,” it may only appear so on a small scale. Broaden the scope, and it’s very efficient.
Food contains a whole lot of different stuff. And your body doesn’t need 100% of the stuff that’s in it.
Also every species needs different things out of their food.
Also, some animals are extremely efficient at extracting nutrients and leave smaller poop relative to their body size. Giraffes leave grape sized poop because they’re remarkably efficient for example.
Evolution isn’t interested in being “efficient,” only in being good enough that the organism can survive long enough to produce baby organisms. As long as that is achieved, clunky and inefficient works fine.
A campfire consumes wood, releasing energy and leaving behind ashes and smoke. Our digestive system is much the same. Our food is broken down, releasing the energy we need to live, leaving behind poo we excrete and co2, which we release in our breath.
It’s all about gaining energy by breaking big molecules into small molecules. Then we get rid of the small molecules.
Everything comes down to poo, from the top of your head to the sole of your shoe. We can figure out what’s wrong with you; by looking at your poo
One important thing to remember is that the things we eat come in different proportions to a human. For example, think of a cow. It is composed of the same types of chemicals as us – carbohydrates, amino acids, fats etc., but in different proportions. If we ate only cow, we would have to consume so much of it to obtain our requirement of the rarest amino acid, which would mean consuming too much of the others types. These would then have to be excreted.
Multiply this logic by all the other foods we eat, and you can see we will always end up with some extra compounds that need to be excreted.
I’ve experimented with eating carnivore, and the poops are really interesting. Very infrequent and very small, with no symptoms of constipation. You utilize basically everything when all you’re eating is meat. The carnivore hypothesis is that we evolved over a million years surviving primarily on meat, and eating plants really only in times of scarcity. I’m seeing more and more studies indicating that’s probably true, and if so your question is poignant; we aren’t really designed to be eating as many plants as we currently do.
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