why do humans need to eat many different kind of foods to get their vitamins etc but large animals like cows only need grass to survive?
In: Biology
At least one thing is that we can’t make vitamin C ourselves, which is a negative mutation we have compared to other animals.
I’m not going to try to explain why humans and animals eat different foods because I don’t know enough about it myself.
What I can tell you is that humans *can* survive on extremely limited diets. They just won’t be as healthy as someone who eats different kinds of foods.
1. Different animal’s digestive systems work very differently
2. You could survive on only potatoes, you would just be far less healthy and have a reduced lifespan, like many animals in the wild vs those in captivity.
Part of it is they’re bulk feeders. Cows will eat 20+ pounds of food a day, up to nearly 40 lbs for meat cows being fed for fast weight gain. They spend a huge portion of their waking hours just eating, with an otherwise sedentary life.
From this enormous food intake they can extract a decent quantity of nutrients that are relatively scarce in their diet. For more complex nutrients they basically carry around a biological factory in their gut to process the vegetable matter into all the proteins they need from their diet.
Wild deer sometimes eat dirt, well if they can they find a salt lick. But they still go looking for minerals not found in the plants they eat. They also occasionally munch baby birds. Possibly other small wildlife, but I know about the birds. It’s a bit like the way a dog or cat sometimes eats grass.
In addition to the ‘efficiently breaking down grass’ thing, and the ‘they eat a variety of plants’ thing, there’s also the fact that species typically evolve the ability to make vitamins that they can’t get easily in their diet. For example, humans make vitamin D because there aren’t many food sources of it, but we can’t make vitamin C, but can find it in food. But other species can make their own vitamin C.
It’s a trade off between needing to find a variety of food and not needing the cellular machines to make more stuff.
Ruminants like cows are able to extract more nutrients from vegetation than we are, due to their specially adapted digestive system and gut flora.
Ruminants ferment food in their four-chambered stomach over an extended period, which enables their gut bacteria to break down complex carbohydrates, proteins, fiber, which in turn synthesize their own nutrients that the host can absorb.
Additionally, ruminants will consume animal bones in order to obtain phosphate and calcium if they’re not able to obtain it elsewhere in their diet.
We don’t. We just like to. Humans can survive on very simple diets. Gauchos would live entirely on beef for example.
Because their digestive system is centered around their natural diet. People would naturally eat all different kinds of things, but cows would only normally eat grass. I’m a horse owner, and sometimes I find that my horses will be eating dirt. This is because they can tell they have mineral deficiency so they take it into their own hands and eat dirt to get those minerals. It’s always a certain time of the year when my horses are coming in from pasture with muddy mouths, so then I’ll go buy a mineral block for them to lick or I’ll buy them some loose minerals to sprinkle in their feed. I like to leave blocks, because then they can decide when they need it and when they don’t because too much mineral could cause issues and it’s more natural for them that way. I’ve seen people with cows leave troughs of loose mineral in the pastures and the cows take a few mouthfuls when they feel like they need it. Digestive systems in large animals are so so different from those of humans
In short… because as humans got smarter, our diets became better and more diverse because we had the anatomy and ability to get better food. Therefore our digestive system became much more streamlined and simple. That means it doesn’t pull as many nutrients from each meal, cuz we have trained our guts that it doesn’t need to.
Extra details… The human brain has tripled in size over the last 3 million years. This is because humans began to eat a wider range of food, and began to cook our food. This meant the digestive system needed to work way less than it did before. Less energy to the gut, meant more energy to the brain.
Better food = bigger brain.
You can see this in the animal kingdom, as animals with very simple, nutrient deficient diets, tend to have very small brains. The body has to spend so much energy on the digestive system, that little goes to the brain, and evolution keeps the brain small.
TLDR; We need better food cuz we eat better food, and we made our body accept that.
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