Hugo, 6 years old: “Why do we have to poop? »

• Our food is digested before the gut expels some of it as poop, according to our partner The Conversation.

• Some animals also "recycle" their poo (and sometimes their pee).

• This analysis was conducted by Christian Graff, a neuroscientist.

Like all animals, humans eat and poop.

Just as waste must come out of a house, the remains of food that our body does not use come out the back and the front.

To grow, to stay fit and to move, we need matter and energy.

Matter is what gives size and weight to things and people.

Energy is what warms them, what makes them move and transform.

Where can a person like you or a small animal find this material to grow and grow?

How to find this energy that warms us, makes us move and transforms a kitten into a tomcat?

By eating certain things, what we call food.

The things we eat are on the one hand plants (seeds, fruits, vegetables for example) and on the other hand animals (cows, chickens, fish etc).

Often these cooked plants and animals no longer recognize each other: flour, cakes, meat, nuggets… but all our food comes from other beings that were alive.

Birds and mice eat sunflower seeds, cats eat mice.

Rabbits eat carrots, foxes eat rabbits.

And humans eat carrots and rabbits.

Everyone poops.

Living beings are made up of organs, which are different for each species: for plants, these are the leaves, stems, roots, etc.

;

for animals these are the skin, the muscles, the brain, the intestines, etc.

These different organs are all made of tiny bricks of matter, which are called the molecules of life.

Like the pieces of Lego and Playmobil, the molecules that form all the organs of different living things are the same, or they look very similar.

The molecules that make carrots and foxes, mice and cats, children and parents are the same, or they look a lot alike.

Digestion: how does it work?

When food arrives in our belly, our intestines prepare a kind of recycling.

Food is cut into pieces which are molecules or packets of molecules (macromolecules).

It is digestion.

The intestine sorts these pieces: it sends the molecules that can be useful to the organs into the blood, and the rest, what it cannot cut or recover, continues its way to the end, it is the poo .

The molecules (little bricks) retained in the blood can be used in two ways:

• Some are used as construction material, they give matter to the organs of the body.

  With them, children and growing kittens build their growing organs brick by brick;

  adults maintain their worn-out organs by replacing destroyed molecules with spare parts.

• But many molecules, especially sugar, also give energy.

  This energy is used to move, to heat the body and to activate the construction of the organs.

  These molecules are consumed, which means that they are destroyed, like burning wood or the gasoline of an engine, to give heat and movement.

  
  

  And as a fuel leaves smoke and ash, the remains of the molecules thus consumed also leave our body, in the air of our breath (carbon dioxide) or in the water that we pee.

Our "BIOLOGY" file

Sometimes what is in the trash of a house still finds its use.

Some animals even recycle poop and pee.

For example, foxes show others where they have been by putting their droppings on stones, and tomcats by spraying the walls with strong-smelling pee.

On the other hand, their droppings, cats prefer to bury them;

it must be said that when hungry mice eat cat droppings, they carry their germs.

But rabbits eat their own droppings: the grass they quickly swallow is not well digested the first time it passes through the intestines, and this allows them to make reserves to eat later in their burrow well outside. shelter from foxes.

Science

Children's questions: "What is a good microbe?"

asks Alexandre (10 years old)

Planet

Children's questions: "Why does the rabbit eat its droppings?"

asks Rose (8 years old)

This analysis was written by Christian Graff, lecturer in neuroscience at the University of Grenoble Alpes.

Access to this content has been blocked to respect your choice of consent

By clicking on "

", you accept the deposit of cookies by external services and will thus have access to the content of our partners

I ACCEPT

And to better remunerate 20 Minutes, do not hesitate to accept all cookies, even for one day only, via our "I accept for today" button in the banner below.

More information on the Cookie Management Policy page.

• Health

• Video

• The Conversation

• Biology

• Feed

• Animals